RASNZ_02_20_2020
Royal Astronomical Society of New Zealand
eNewsletter: No. 230, 20 February 2020 Affiliated Societies are welcome to reproduce any item in this email newsletter or on the RASNZ website www.rasnz.org.nz in their own newsletters provided an acknowledgement of the source is also included.
Contents
1. Faint Betelgeuse Imaged
2. 2020 Northern Star Party, Waharau, March 20-22
3. Annual General Meeting Deadline
4. Subscriptions and Reports Due
5. The Solar System in March
6. 2020 Beatrice-Hill-Tinsley Lectures
7. 2020 Conference and RASNZ Centenary
8. Call for Papers for 2020 RASNZ Conference
9. Star Parties in 2020
10. Variable Star News
11. Dark Energy Explained?
12. Stars in the Magellanic Stream
13. Big New Solar Telescope
14. How to Join the RASNZ
15. Gifford-Eiby Lecture Fund
16. Quotes
1. Faint Betelgeuse Imaged
Using the European Southern Observatory's Very Large Telescope (VLT), astronomers have captured the unprecedented dimming of Betelgeuse, a red supergiant star in the constellation of Orion. The stunning new images of the star's surface show not only the fading red supergiant but also how its apparent shape is changing.
Betelgeuse has been a beacon in the night sky for stellar observers but it began to dim late last year. At the time of writing Betelgeuse is at about 36% of its normal brightness, a change noticeable even to the naked eye. Astronomy enthusiasts and scientists alike were excitedly hoping to find out more about this unprecedented dimming.
A team led by Miguel Montargès, an astronomer at KU Leuven in Belgium, has been observing the star with ESO's VLT since December, aiming to understand why it's becoming fainter. Among the first observations to come out of their campaign is a stunning new image of Betelgeuse's surface, taken late last year with the SPHERE instrument.
The team also happened to observe the star with SPHERE in January 2019, before it began to dim, giving us a before-and-after picture of Betelgeuse. Taken in visible light, the images highlight the changes occurring to the star both in brightness and in apparent shape.
Many astronomy enthusiasts wondered if Betelgeuse's dimming meant it was about to explode. Like all red supergiants, Betelgeuse will one day go supernova, but astronomers don't think this is happening now. They have other hypotheses to explain what exactly is causing the shift in shape and brightness seen in the SPHERE images. "The two scenarios we are working on are a cooling of the surface due to exceptional stellar activity or dust ejection towards us," says Montargès. "Of course, our knowledge of red supergiants remains incomplete, and this is still a work in progress, so a surprise can still happen."
Montargès and his team needed the VLT to study the star, which is over 700 light-years away, and gather clues on its dimming. Instruments on the VLT allow observations from the visible to the mid-infrared, meaning astronomers can see both the surface of Betelgeuse and the material around it.
Another new image, obtained with the VISIR instrument on the VLT, shows the infrared light being emitted by the dust surrounding Betelgeuse in December 2019. These observations were made by a team led by Pierre Kervella from the Observatory of Paris who explained that the wavelength of the image is similar to that detected by heat cameras. The clouds of dust, which resemble flames in the VISIR image, are formed when the star sheds its material back into space.
"The phrase 'we are all made of stardust' is one we hear a lot in popular astronomy, but where exactly does this dust come from?" says Emily Cannon, a PhD student at KU Leuven working with SPHERE images of red supergiants. "Over their lifetimes, red supergiants like Betelgeuse create and eject vast amounts of material even before they explode as supernovae. Modern technology has enabled us to study these objects, hundreds of light-years away, in unprecedented detail giving us the opportunity to unravel the mystery of what triggers their mass loss."
See the images at https://www.eso.org/public/news/eso2003/?lang
-- From an ESO press release forwarded by Karen Pollard.
2. 2020 Northern Star Party, Waharau, March 20-22
The Auckland Astronomical Society’s Waharau Dark Sky Weekend is from Friday 20th March, starting 4pm, to Sunday 22nd March, ending at 11am. It will be at Waharau Regional Park, 1748 East Coast Rd, Orere Point, Whakatiwai 2473 (about 1 hours drive from central Auckland).
It will be a weekend of practical astronomy and dark sky observing.
It is great opportunity to spend a weekend viewing the sky from a dark site on Moonless nights thought a range of different telescopes. Bring your telescope or binoculars, but if you don’t have any there will be plenty there for you to look through.
Also the society has telescopes available for hire. Contact Steve Hennerley (027) 245 6441 or Darren Woodley 021776481 email: rental@astronomy.org.nz to get these. Book now as these can become booked out!
During the day on Saturday there will be a full programme of practical astronomy – how to use equipment and various types of telescopes, new equipment demonstrations and an astrophotography workshop.
Films will be shown in the early evening on Friday and Saturday.
Prices:
AAS Member earlybird $20.00. Name received by Wednesday 11th March. Payment received by Friday 13th March.
AAS Member standard $30.00
Non-member earlybird $40.00. Name received by Wednesday 11th March.
Payment received by Friday13th March.
Non-member standard $50.00
These prices include bunk bed type accommodation.
To book please email Gavin Logan: gavinlgn@gmail.com giving the names of the people attending. Phone 021 1441055.
3. Annual General Meeting Deadline
Notices of motion for Annual General Meeting must be submitted to the Executive Secretary by Saturday, 28th March.
The Executive Secretary's email address is
John Drummond
Postal address: John Drummond, PO Box 113, Patutahi 4045.
4. Subscriptions and Reports Due
2020 RASNZ subscriptions are due on the 1st January. See - https://www.rasnz.org.nz/rasnz/payments-and-donations
Section and Group reports are due with the Executive Secretary by 9th March. For more details see By-Laws F1 - F16.
5. The Solar System in March
Dates and times shown are NZDT (UT + 13 hours). Rise and Set times are for Wellington. They will vary by a few minutes elsewhere in NZ. Data is adapted from that shown by GUIDE 9.1
THE SUN and PLANETS in March, Rise & Set, Magnitude & Constellation.
March 1 NZDT March 31 NZDT
Mag Cons Rise Set Mag Cons Rise Set
SUN 26.7 Aqr 6.59am 8.05pm -26.7 Psc 7.33am 7.16pm
Mercury 3.5 Aqr 6.20am 7.22pm 0.0 Aqr 5.17am 6.23pm
Venus -4.3 Psc 10.49am 9.42pm -4.5 Tau 11.39am 8.58pm
Mars 1.1 Sgr 1.47am 4.59pm 0.8 Cap 1.30am 4.18pm
Jupiter -2.0 Sgr 2.37am 5.33pm -2.1 Sgr 1.02am 3.52pm
Saturn 0.7 Sgr 3.20am 6.03pm 0.7 Cap 1.34am 4.13pm
Uranus 5.8 Ari 11.29am 10.10pm 5.9 Ari 9.38am 8.15pm
Neptune 8.0 Aqr 7.37am 8.25pm 8.0 Aqr 5.41am 6.26pm
Pluto 14.5 Sgr 2.57am 5.53pm 14.5 Sgr 1.02am 3.57pm
March 1 NZDT March 29 NZDT
Twilights morning evening morning evening
Civil: start 6.34am, end 8.32pm start 7.08am, end 7.42pm
Nautical: start 6.00am, end 9.06pm start 6.36am, end 8.14pm
Astro: start 5.25am, end 9.41pm start 6.04am, end 8.46pm
March PHASES OF THE MOON, times NZDT & UT
First quarter: Mar 3 at 8.57am (Mar 2, 19:57 UT)
Full Moon: Mar 10 at 6.47am (Mar 9, 17:47 UT)
Last quarter Mar 16 at 10.34pm (09:34 UT)
New Moon: Feb 24 at 10.28pm (09:28 UT)
PLANETS in MARCH
VENUS is the only naked-eye evening planet in March. It sets about 100 minutes after the Sun. It will be rather low, some 10° up and 30° north of due west half an hour after sunset. A conjunction with Neptune on the 8th will give a chance to get a binocular view of the latter 2.2° above Venus.
On the 28th the crescent moon will be some 7° from Venus. Two days later the planet moves into Taurus heading towards the Pleiades.
MERCURY is at its best as a morning object during March. It rises some 40 minutes before the Sun on the 1st with the interval increasing to about 140 minutes in the second half of the month. The planet will then be 14 to 15° up and almost due east an hour before sunrise. With a magnitude 0.0, this will present the best chance of the year to see Mercury as a morning object.
On the morning of the 21st, the moon as a thin crescent, will be just over 3° to the right of, and slightly higher than Mercury
MARS, JUPITER, SATURN and PLUTO are all quite close to one another in the morning sky during March with Saturn lowest. On the 1st Mars will be highest, by the 31st it will be only a degree above Saturn
Mars passes Jupiter on the 21st when it will be 40 arc-minutes to the right of Jupiter in the morning sky. Mars goes on to a very close conjunction with Pluto, at their closest they are only 38 arc-second apart. As seen from NZ they will be some 20 arc-minute apart on the morning of the 23rd and 15 arc-minutes on the 24th. Finally, on the morning of the 31st, Mars will be just over 1° from Saturn. They are a little closer to one another on the first two mornings of April.
The moon passes Mars on March 18. At their closest they will be less than a degree apart. But this stage is not visible from NZ. For NZ, on the morning of the 18th the moon will be 7° above Mars, the following morning it will be nearly 5° below the planet. On the latter date the moon will also be about 4° to the lower right of Saturn and a similar distance above Jupiter
URANUS is a low evening object. It will be 2° above Venus on the 8th. By the end of March it sets 1 hour after the Sun.
NEPTUNE is too close to the Sun to observe in March. It is at conjunction on the 8th.
POSSIBLE BINOCULAR ASTEROIDS in MARCH
March 1 NZDT March 29 NZDT
Mag Cons transit Mag Cons transit
(1) Ceres 9.3 Cap 11.47am 9.3 Cap 10.34am
(4) Vesta 8.3 Tau 6.10pm 8.5 Tau 4.54pm
CERES is a low morning object. It will be just over 3° to the upper right of the crescent moon on the 21st. By the end of March Ceres will be at the opposite side of Capricornus to Saturn and Mars.
VESTA is an evening object. On the 1st it will be less than 1° to the upper right of the moon. An occultation occurs visible from Hawaii. A second close approach takes place on March 29, with Vesta half a degree above the northern limb of the moon. There is another occultation visible from parts of the Pacific well to the north of NZ.
-- Brian Loader
6. 2020 Beatrice-Hill-Tinsley Lectures
The RASNZ Lecture Trust is pleased to announce that the 2020 Beatrice-Hill-Tinsley lecturer is Professor Anna Scaife, Professor of Radio Astronomy at the University of Manchester and Head of the Jodrell Bank Centre for Astrophysics Interferometry Centre of Excellence.
Affiliated Societies are invited to host Professor Scaife during the lecture series which will be occurring in the three weeks prior to the 2020 RASNZ conference in early May. Expressions of interest should be sent to the lecture trust secretary at LectureTrust@rasnz.org.nz at the earliest opportunity before February 28th.
For general information about the BHT lectures see
https://www.rasnz.org.nz/rasnz/beatrice-hill-tinsley-lectures
-- From https://www.rasnz.org.nz/
7. 2020 Conference and RASNZ Centenary
It is a pleasure to announce that the next conference of the Royal Astronomical Society of New Zealand (RASNZ) will be held at the Wharewaka Function Centre on Wellington waterfront over the weekend of 8 - 10 May 2020. The Wellington Astronomical Society is hosting the Conference.
This year is the 100th anniversary of the formation of the Society and to honour this special occasion we will be welcoming four invited speakers. They will be Dr Dom Pesce (Black Hole Initiative, Harvard University), Professor Anna Scaife and Dr Rene Breton (Manchester University/Jodrell Bank) and Dr Chris Lintott (Oxford University). This year the Fellows´ Lecture will be given by long standing Society member and past president John Drummond. Titles and abstracts for these talks will be released when they are available.
As the programme will commence at the earlier than usual time at 1pm on Friday we encourage as many as possible to make their travel arrangements to arrive in the city during the morning.
The conference will be preceded by a Dark Sky Workshop on the morning of
Thursday 7 May. The workshop will consist of short talks on relevant key local and international dark sky updates and discussion/demonstration on topics such as sky quality measurements and dark sky friendly lighting.
The RASNZ website now has available the conference brochure, on-line registration (and downloadable form) and paper submission (via the registration page). See it all here: http://www.rasnz.org.nz/groups-news-events/rasnz-conference.
Please consider participating in this Conference as RASNZ celebrates its centenary - we look forward to seeing you there.
-- Glen Rowe, Chair, Standing Conference Committee.
8. Call for Papers for 2020 RASNZ Conference
The RASNZ Standing Conference Committee (SCC) invites and encourages anyone interested in New Zealand astronomy to submit oral or poster papers, with titles and abstracts due by 1 April 2020 or until such time as the SCC deems the conference programme to be full. The link to the paper submission form can be found on the RASNZ Conference website http://rasnz.org.nz/groups-news-events/rasnz-conference. Please note that you must be registered for the conference to give an oral presentation, and for your convenience a link has been provided if you wish to do this when you submit a paper.
We look forward to receiving your submissions and seeing you at the conference. Please feel free to forward this message to anyone who may find it of interest.
For further information on the RASNZ Conference, registration details and associated events please visit the conference website at http://rasnz.org.nz/groups-news-events/rasnz-conference.
-- Warwick Kissling, RASNZ Standing Conference Committee
9. Star Parties in 2020
The following star parties are planned for 2020:
Northern Star Party, Waharau, March 20-22. See Item 2, above.
Stargazers Getaway 2020 Camp Iona, Friday September 18th to Sunday 20th. This is New Moon, so we are targeting this weekend for dark skies! See
https://www.facebook.com/events/943327669369996/
NACAA: The 29th NACAA conference will be held in the NSW (Australia) regional city of Parkes (where the world-famous Parkes Radio Telescope is) over the 2020 Easter weekend, Friday April 10th – Monday 13th. For more details see http://nacaa.org.au/2020/about
-- Mostly from 'Keeping in Touch' #34, 27th Sept 2019.
10. Variable Star News
Recent Publication
Studies by some Variable Star South (VSS) workers on a four star system has been featured in an AAVSO Community Newsletter, email 4th February 2020. The paper combines a number of studies on the variable QZ Carinae which consists of two binary pairs. To complicate the analysis one of the stars exhibits small light variations. One of the components is a massive star. The publication reference is Blackford M. et al (2020) JAAVSO 48 (No 1). QZ Car was discovered in 1971 by Brian Marino and Stan Walker of Auckland Observatory.
There are six VSS authors, M Blackford, S Walker, E Budding, G Bolt, D Blane, T Bohlsen; additionally there are six authors from the BRITE team. The BRITE-Constellation collaboration (advised in AAVSO posting 2 Oct 2016) combines satellite observations and ground-based photometric and spectrographic measurements on selected stellar targets.
The published work focusses on the period of the two binary pairs, one of which is an eclipsing system. Such systems can help determine masses of the component stars. The posting by the Journal Editor noted that the determination of exact masses of hot massive stars is difficult and the work undertaken will assist in establishing the values in this system.
Betelgeuse.
Have you been looking at the constellation Orion recently? To me it looks unbalanced - the bright star at the hunter’s shoulder (Betelgeuse) no longer balances the diagonally opposite bright blue star Rigel at his left foot. The start of the deep fade of Betelgeuse caused a storm of publicity and the steep decline has captured a lot of interest. As at the 18th of February it is at about V-filter magnitude 1.8, a far deeper minimum than the cycles immediately beforehand (decrease in magnitude approximately 0.5). Perhaps the star has entered a new pulsation mode, but other explanations are possible. It does appear that the light intensity is plateauing so make sure you see this new view of the constellation before the star recovers its usual brightness of about V magnitude 0.5. There is still plenty of analysis to go before we complete this story.
-- Alan Baldwin
11. Dark Energy Explained?
Cosmologists don’t enter their profession to tackle the easy questions, but there is one paradox that has reached staggering proportions.
Since the big bang, the universe has been expanding, but the known laws of physics suggest that the inward tug of gravity should be slowing down this expansion. In reality, though, the universe is ballooning at an accelerating rate.
Scientists have come up with a name – dark energy – for the mysterious agent that is allowing the cosmos to expand so rapidly and which is estimated to account for 70% of the contents of the universe. But ultimately nobody knows what the stuff actually is.
“It’s the big elephant in the room,” says Prof Claudia de Rham, a theoretical physicist at Imperial College. “It’s very frustrating.”
Change could be afoot. De Rham has pioneered a radical theory that could hold the key to why the universe is expanding faster and faster and explain the nature of dark energy. The theory, known as massive gravity, modifies Einstein’s general relativity, positing that the hypothetical particles (gravitons) that mediate the gravitational force themselves have a mass. In Einstein’s version, gravitons are assumed to be massless.
If gravitons have a mass, then gravity is expected to have a weaker influence on very large distance scales, which could explain why the expansion of the universe has not been reined in. “One possibility is that you may not need to have dark energy – or rather, gravity itself fulfils that role,” says De Rham.
The work marks a breakthrough in a century-long quest to build a working theory of massive gravity. Despite successive efforts, previous versions of the theory had the unfortunate feature of predicting the instantaneous decay of every particle in the universe – an intractable issue that mathematicians refer to as a “ghost”. “Very clever people had worked on this and the arguments were very compelling,” says De Rham. “People thought it would be impossible to make it work.”
But in 2011, when De Rham and her collaborators, Gregory Gabadadze from New York University and Andrew Tolley from Imperial College London, published a landmark paper on massive gravity, the response was swift and hostile.
In the end, the theory stood up and has been gaining traction in the past decade. “That’s what science does. At the end there’s a result based on maths and logic,” De Rham says. “If one is equal to one, we can all agree on that. Maths don’t lie.”
In the latest acknowledgement of the breakthrough, De Rham was recipient of the $100,000 (£75,000) Blavatnik Award for Young Scientists, two years after winning the Adams prize, one of the University of Cambridge’s oldest and most prestigious awards.
De Rham is quick to point out that at this stage, massive gravity is still just a theory. Mathematically it checks out, but we don’t know whether it reflects empirical reality. But with the advent of gravitational wave astronomy, it will be possible to test predictions of the theory over the next decade and beyond.
“It would be amazing if it was shown to be right,” she says. “That may or may not happen, but what will happen is that we’ll have a much better fundamental understanding of gravity and that’s just something so deep, it’s one of the big questions today.”
De Rham’s more recent work covers other aspects of gravity. She is interested in the speed of gravity, which has never been directly measured and which theory predicts could in some circumstances be faster than light. She is also investigating whether gravity, like light, moves at different speeds through different materials. If it does, gravitational rainbows would exist that might be viewable with gravitational wave telescopes.
As a new generation of gravitational wave observatories, such as ESA’s space-based observatory, Lisa, start gathering faint signals from the cosmos in the next decade, De Rham hopes to close in on some answers. “It’s going to be such a high level of science that we can do,” says De Rham. “It’s beautiful.”
-- Abridged from Hannah Devlin's article in The Guardian, 25 January 2020. See the original at
https://www.theguardian.com/science/2020/jan/25/has-physicists-gravity-theory-solved-impossible-dark-energy-riddle
12. Stars in the Magellanic Stream
Ground- and space-based observations have revealed a group of stars at the head of the giant stream of gas burrowing its way through the Milky Way. A newfound cluster of young stars sits on the periphery of the Milky Way. These stars probably formed from material originating from neighbouring dwarf galaxies called the Magellanic Clouds.
The collection of young stars in a surprising location — deep in the halo of old stars surrounding the Milky Way. Adrian Price-Whelan (Flatiron Institute) found the loose cluster while digging through the second data release from the European Gaia mission. Gaia is currently mapping the motions and locations of more than 1 billion stars, extending astronomers’ reach from just a few hundred light-years to most of our galaxy. The newly found stars clearly move together as a set. At 116 million years old, the cluster is young and also fairly lightweight, similar to the Pleiades in both age and mass.
But, unlike the Pleiades, these stars lie far away: some 94,000 light-years, roughly 200 times farther from Earth than the iconic Seven Sisters. They’re also spread out, spanning some 1,600 light-years. That means they’re probably no longer gravitationally bound together and therefore not a cluster in the technical sense of the word.
By rights, the stars shouldn’t be out there. There’s not much star-making gas in the Milky Way’s halo and the gas that is there is too hot and spread out to collapse to create new suns. What little cool stuff there is is almost entirely in the Magellanic Stream, a vast ribbon of (mostly) hydrogen gas traveling with the Large and Small Magellanic Clouds through our galaxy’s outer regions. And the stars appear to be sailing at the head of that ribbon of gas.
To confirm the stars’ location, Price-Whelan, David Nidever (Montana State University), and their colleagues took spectra of 28 of the brightest stars in the group. The measurements confirmed the stars’ ages and that they have fairly pristine compositions, polluted with only small quantities of heavy elements. The compositions look nothing like stellar new-borns in the Milky Way, but they match the gas in the stream’s leading arm. The stars’ velocities also line up with that of the stream.
Combined, the various observations led the team to conclude these stars likely formed from the gas at the head of the Magellanic Stream, Price-Whelan and Nidever reported at the winter American Astronomical Society meeting in Honolulu. The results also appear in two papers in the Astrophysical Journal.
Observers have been looking for stars associated with the Magellanic Stream for decades, explains Jeremy Bailin (University of Alabama). Astronomers don’t know how far away the stream is because it’s hard to determine distances to a cloud of hydrogen gas. But stars are different — and we can learn all sorts of cool things with stars.
The difficulty with distance might explain why the new cluster’s estimated distance is roughly half the number that’s often used for the Magellanic Stream. If the stream really is that much closer, it could mean that its gas — and the gas of the Magellanic Clouds — will dump into the Milky Way and spur starbirth sooner than astronomers predicted.
The stars lie at the leading edge of the stream, though, not in it. The team thinks this offset exists because, as the stream ploughs through the hot gas in the halo, it feels a drag. The stars don’t, however. Over time, the gas would slow down and fall behind. Indeed, the stars’ ages match when the stream passed through our galaxy’s outer disk in the recent past. That passage could have compressed the stream’s gas, spurring starbirth.
-- From Camille M. Carlisle's article on Sky & Telescope's webpage at
https://www.skyandtelescope.com/astronomy-news/baby-stars-found-ancient-part-milky-way-galaxy/
For more on Gaia's results see
https://www.skyandtelescope.com/astronomy-news/gaia-maps-1-7-billion-stars-widens-cosmic-census/
13. Big New Solar Telescope
First images from the U.S. National Science Foundation's Daniel K. Inouye Solar Telescope reveal unprecedented detail of the Sun's surface and preview the world-class products to come from this preeminent 4-meter solar telescope. NSF's Inouye Solar Telescope, on the summit of Haleakala, Maui, in Hawai'i, will enable a new era of solar science and a leap forward in understanding the Sun and its impacts on our planet.
Activity on the Sun, known as space weather, can affect systems on Earth. Magnetic eruptions on the Sun can impact air travel, disrupt satellite communications, and bring down power grids, causing long-lasting blackouts and disabling technologies such as GPS.
The first images from the Inouye Solar Telescope show a close-up view of the Sun's surface, which can provide important detail for scientists. The images show a pattern of turbulent "boiling" plasma that covers the entire Sun. The cell-like structures -- each about 1000 km across -- are the signature of violent motions that transport heat from the inside of the Sun to its surface. That hot solar plasma rises in the bright centres of "cells," cools, then sinks below the surface in dark lanes in a process known as convection.
The telescope will be able to map the magnetic fields within the Sun's corona, where solar eruptions occur that can impact life on Earth. This telescope will improve our understanding of what drives space weather and ultimately help forecasters better predict solar storms.
The Sun is our nearest star -- a gigantic nuclear reactor that burns about 5 million tons of hydrogen fuel every second. It has been doing so for about 5 billion years and will continue for the other 4.5 billion years of its lifetime. All that energy radiates into space in every direction. The tiny fraction that hits Earth makes life possible. In the 1950s, scientists figured out that a solar wind blows from the Sun to the edges of the solar system. They also concluded for the first time that we live inside the atmosphere of this star. But many of the Sun's most vital processes continue to confound scientists.
"On Earth, we can predict if it is going to rain pretty much anywhere in the world very accurately, and space weather just isn't there yet," said Matt Mountain, president of the Association of Universities for Research in Astronomy (AURA), which manages the Inouye Solar Telescope. "Our predictions lag behind terrestrial weather by 50 years, if not more. What we need is to grasp the underlying physics behind space weather, and this starts at the Sun, which is what the Inouye Solar Telescope will study over the next decades."
The motions of the Sun's plasma constantly twist and tangle solar magnetic fields. Twisted magnetic fields can lead to solar storms that can negatively affect our technology-dependent modern lifestyles. During 2017's Hurricane Irma, the National Oceanic and Atmospheric Administration reported that a simultaneous space weather event brought down radio communications used by first responders, aviation and maritime channels for eight hours on the day the hurricane made landfall.
Finally resolving these tiny magnetic features is central to what makes the Inouye Solar Telescope unique. It can measure and characterize the Sun's magnetic field in more detail than ever seen before and determine the causes of potentially harmful solar activity.
Better understanding the origins of potential disasters will enable governments and utilities to better prepare for inevitable future space weather events. It is expected that notification of potential impacts could occur earlier -- as much as 48 hours ahead of time instead of the current standard, which is about 48 minutes. This would allow more time to secure power grids and critical infrastructure and to put satellites into safe mode.
To achieve the proposed science, this telescope required important new approaches to its construction and engineering. Built by NSF's National Solar Observatory and managed by AURA, the Inouye Solar Telescope combines a 4-metre mirror -- the world's largest for a solar telescope -- with unparalleled viewing conditions at the 3,000-metre Haleakala summit.
Focusing 13 kilowatts of solar power generates enormous amounts of heat -- heat that must be contained or removed. A specialized cooling system provides crucial heat protection for the telescope and its optics. More than seven miles of piping distribute coolant throughout the observatory, partially chilled by ice created on site during the night.
The dome enclosing the telescope is covered by thin cooling plates that stabilize the temperature around the telescope, helped by shutters within the dome that provide shade and air circulation. The "heat-stop" (a high-tech, liquid-cooled, doughnut-shaped metal) blocks most of the sunlight's energy from the main mirror, allowing scientists to study specific regions of the Sun with unparalleled clarity.
The telescope also uses state-of-the-art adaptive optics to compensate for blurring created by Earth's atmosphere. The design of the optics ("off-axis" mirror placement) reduces bright, scattered light for better viewing and is complemented by a cutting-edge system to precisely focus the telescope and eliminate distortions created by the Earth's atmosphere. This system is the most advanced solar application to date.
NSF's new ground-based Inouye Solar Telescope will work with space-based solar observation tools such as NASA's Parker Solar Probe (currently in orbit around the Sun) and the European Space Agency/NASA Solar Orbiter. The three solar observation initiatives will expand the frontiers of solar research and improve scientists' ability to predict space weather.
-- From a US National Science Foundation press release forwarded by Karen Pollard. For images see https://www.nso.edu/inouye-solar-telescope-first-light/
14. How to Join the RASNZ
RASNZ membership is open to all individuals with an interest in
astronomy in New Zealand. Information about the society and its
objects can be found at
http://rasnz.org.nz/rasnz/membership-benefits
A membership form can be either obtained from treasurer@rasnz.co.nz or
by completing the online application form found at
http://rasnz.org.nz/rasnz/membership-application
Basic membership for the 2020 year starts at $40 for an ordinary
member, which includes an electronic subscription to our journal
'Southern Stars'.
15. Gifford-Eiby Lecture Fund
The RASNZ administers the Gifford-Eiby Memorial Lectureship Fund to
assist Affiliated Societies with travel costs of getting a lecturer
or instructor to their meetings. Details are in RASNZ By-Laws Section
H and at http://rasnz.org.nz/rasnz/ge-fund
The application form is at
http://rasnz.org.nz/Downloadable/RASNZ/GE_Application2019.pdf
16. Quotes
"The greatest threat to our planet is the belief that someone else will save it." - Explorer Robert Swan quoted in 'NZ Listener' 22 February 2020.
"Defending light pollution with the argument that we need light to see at night is like defending unending rock festivals with the argument that we need sound to communicate. It's not a yes/no question, but a question of how much, where, and when." -- Annette Krop-Benesch in La Palma #lightpollution retweeted.
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
eNewsletter: No. 230, 20 February 2020 Affiliated Societies are welcome to reproduce any item in this email newsletter or on the RASNZ website www.rasnz.org.nz in their own newsletters provided an acknowledgement of the source is also included.
Contents
1. Faint Betelgeuse Imaged
2. 2020 Northern Star Party, Waharau, March 20-22
3. Annual General Meeting Deadline
4. Subscriptions and Reports Due
5. The Solar System in March
6. 2020 Beatrice-Hill-Tinsley Lectures
7. 2020 Conference and RASNZ Centenary
8. Call for Papers for 2020 RASNZ Conference
9. Star Parties in 2020
10. Variable Star News
11. Dark Energy Explained?
12. Stars in the Magellanic Stream
13. Big New Solar Telescope
14. How to Join the RASNZ
15. Gifford-Eiby Lecture Fund
16. Quotes
1. Faint Betelgeuse Imaged
Using the European Southern Observatory's Very Large Telescope (VLT), astronomers have captured the unprecedented dimming of Betelgeuse, a red supergiant star in the constellation of Orion. The stunning new images of the star's surface show not only the fading red supergiant but also how its apparent shape is changing.
Betelgeuse has been a beacon in the night sky for stellar observers but it began to dim late last year. At the time of writing Betelgeuse is at about 36% of its normal brightness, a change noticeable even to the naked eye. Astronomy enthusiasts and scientists alike were excitedly hoping to find out more about this unprecedented dimming.
A team led by Miguel Montargès, an astronomer at KU Leuven in Belgium, has been observing the star with ESO's VLT since December, aiming to understand why it's becoming fainter. Among the first observations to come out of their campaign is a stunning new image of Betelgeuse's surface, taken late last year with the SPHERE instrument.
The team also happened to observe the star with SPHERE in January 2019, before it began to dim, giving us a before-and-after picture of Betelgeuse. Taken in visible light, the images highlight the changes occurring to the star both in brightness and in apparent shape.
Many astronomy enthusiasts wondered if Betelgeuse's dimming meant it was about to explode. Like all red supergiants, Betelgeuse will one day go supernova, but astronomers don't think this is happening now. They have other hypotheses to explain what exactly is causing the shift in shape and brightness seen in the SPHERE images. "The two scenarios we are working on are a cooling of the surface due to exceptional stellar activity or dust ejection towards us," says Montargès. "Of course, our knowledge of red supergiants remains incomplete, and this is still a work in progress, so a surprise can still happen."
Montargès and his team needed the VLT to study the star, which is over 700 light-years away, and gather clues on its dimming. Instruments on the VLT allow observations from the visible to the mid-infrared, meaning astronomers can see both the surface of Betelgeuse and the material around it.
Another new image, obtained with the VISIR instrument on the VLT, shows the infrared light being emitted by the dust surrounding Betelgeuse in December 2019. These observations were made by a team led by Pierre Kervella from the Observatory of Paris who explained that the wavelength of the image is similar to that detected by heat cameras. The clouds of dust, which resemble flames in the VISIR image, are formed when the star sheds its material back into space.
"The phrase 'we are all made of stardust' is one we hear a lot in popular astronomy, but where exactly does this dust come from?" says Emily Cannon, a PhD student at KU Leuven working with SPHERE images of red supergiants. "Over their lifetimes, red supergiants like Betelgeuse create and eject vast amounts of material even before they explode as supernovae. Modern technology has enabled us to study these objects, hundreds of light-years away, in unprecedented detail giving us the opportunity to unravel the mystery of what triggers their mass loss."
See the images at https://www.eso.org/public/news/eso2003/?lang
-- From an ESO press release forwarded by Karen Pollard.
2. 2020 Northern Star Party, Waharau, March 20-22
The Auckland Astronomical Society’s Waharau Dark Sky Weekend is from Friday 20th March, starting 4pm, to Sunday 22nd March, ending at 11am. It will be at Waharau Regional Park, 1748 East Coast Rd, Orere Point, Whakatiwai 2473 (about 1 hours drive from central Auckland).
It will be a weekend of practical astronomy and dark sky observing.
It is great opportunity to spend a weekend viewing the sky from a dark site on Moonless nights thought a range of different telescopes. Bring your telescope or binoculars, but if you don’t have any there will be plenty there for you to look through.
Also the society has telescopes available for hire. Contact Steve Hennerley (027) 245 6441 or Darren Woodley 021776481 email: rental@astronomy.org.nz to get these. Book now as these can become booked out!
During the day on Saturday there will be a full programme of practical astronomy – how to use equipment and various types of telescopes, new equipment demonstrations and an astrophotography workshop.
Films will be shown in the early evening on Friday and Saturday.
Prices:
AAS Member earlybird $20.00. Name received by Wednesday 11th March. Payment received by Friday 13th March.
AAS Member standard $30.00
Non-member earlybird $40.00. Name received by Wednesday 11th March.
Payment received by Friday13th March.
Non-member standard $50.00
These prices include bunk bed type accommodation.
To book please email Gavin Logan: gavinlgn@gmail.com giving the names of the people attending. Phone 021 1441055.
3. Annual General Meeting Deadline
Notices of motion for Annual General Meeting must be submitted to the Executive Secretary by Saturday, 28th March.
The Executive Secretary's email address is
John Drummond
Postal address: John Drummond, PO Box 113, Patutahi 4045.
4. Subscriptions and Reports Due
2020 RASNZ subscriptions are due on the 1st January. See - https://www.rasnz.org.nz/rasnz/payments-and-donations
Section and Group reports are due with the Executive Secretary by 9th March. For more details see By-Laws F1 - F16.
5. The Solar System in March
Dates and times shown are NZDT (UT + 13 hours). Rise and Set times are for Wellington. They will vary by a few minutes elsewhere in NZ. Data is adapted from that shown by GUIDE 9.1
THE SUN and PLANETS in March, Rise & Set, Magnitude & Constellation.
March 1 NZDT March 31 NZDT
Mag Cons Rise Set Mag Cons Rise Set
SUN 26.7 Aqr 6.59am 8.05pm -26.7 Psc 7.33am 7.16pm
Mercury 3.5 Aqr 6.20am 7.22pm 0.0 Aqr 5.17am 6.23pm
Venus -4.3 Psc 10.49am 9.42pm -4.5 Tau 11.39am 8.58pm
Mars 1.1 Sgr 1.47am 4.59pm 0.8 Cap 1.30am 4.18pm
Jupiter -2.0 Sgr 2.37am 5.33pm -2.1 Sgr 1.02am 3.52pm
Saturn 0.7 Sgr 3.20am 6.03pm 0.7 Cap 1.34am 4.13pm
Uranus 5.8 Ari 11.29am 10.10pm 5.9 Ari 9.38am 8.15pm
Neptune 8.0 Aqr 7.37am 8.25pm 8.0 Aqr 5.41am 6.26pm
Pluto 14.5 Sgr 2.57am 5.53pm 14.5 Sgr 1.02am 3.57pm
March 1 NZDT March 29 NZDT
Twilights morning evening morning evening
Civil: start 6.34am, end 8.32pm start 7.08am, end 7.42pm
Nautical: start 6.00am, end 9.06pm start 6.36am, end 8.14pm
Astro: start 5.25am, end 9.41pm start 6.04am, end 8.46pm
March PHASES OF THE MOON, times NZDT & UT
First quarter: Mar 3 at 8.57am (Mar 2, 19:57 UT)
Full Moon: Mar 10 at 6.47am (Mar 9, 17:47 UT)
Last quarter Mar 16 at 10.34pm (09:34 UT)
New Moon: Feb 24 at 10.28pm (09:28 UT)
PLANETS in MARCH
VENUS is the only naked-eye evening planet in March. It sets about 100 minutes after the Sun. It will be rather low, some 10° up and 30° north of due west half an hour after sunset. A conjunction with Neptune on the 8th will give a chance to get a binocular view of the latter 2.2° above Venus.
On the 28th the crescent moon will be some 7° from Venus. Two days later the planet moves into Taurus heading towards the Pleiades.
MERCURY is at its best as a morning object during March. It rises some 40 minutes before the Sun on the 1st with the interval increasing to about 140 minutes in the second half of the month. The planet will then be 14 to 15° up and almost due east an hour before sunrise. With a magnitude 0.0, this will present the best chance of the year to see Mercury as a morning object.
On the morning of the 21st, the moon as a thin crescent, will be just over 3° to the right of, and slightly higher than Mercury
MARS, JUPITER, SATURN and PLUTO are all quite close to one another in the morning sky during March with Saturn lowest. On the 1st Mars will be highest, by the 31st it will be only a degree above Saturn
Mars passes Jupiter on the 21st when it will be 40 arc-minutes to the right of Jupiter in the morning sky. Mars goes on to a very close conjunction with Pluto, at their closest they are only 38 arc-second apart. As seen from NZ they will be some 20 arc-minute apart on the morning of the 23rd and 15 arc-minutes on the 24th. Finally, on the morning of the 31st, Mars will be just over 1° from Saturn. They are a little closer to one another on the first two mornings of April.
The moon passes Mars on March 18. At their closest they will be less than a degree apart. But this stage is not visible from NZ. For NZ, on the morning of the 18th the moon will be 7° above Mars, the following morning it will be nearly 5° below the planet. On the latter date the moon will also be about 4° to the lower right of Saturn and a similar distance above Jupiter
URANUS is a low evening object. It will be 2° above Venus on the 8th. By the end of March it sets 1 hour after the Sun.
NEPTUNE is too close to the Sun to observe in March. It is at conjunction on the 8th.
POSSIBLE BINOCULAR ASTEROIDS in MARCH
March 1 NZDT March 29 NZDT
Mag Cons transit Mag Cons transit
(1) Ceres 9.3 Cap 11.47am 9.3 Cap 10.34am
(4) Vesta 8.3 Tau 6.10pm 8.5 Tau 4.54pm
CERES is a low morning object. It will be just over 3° to the upper right of the crescent moon on the 21st. By the end of March Ceres will be at the opposite side of Capricornus to Saturn and Mars.
VESTA is an evening object. On the 1st it will be less than 1° to the upper right of the moon. An occultation occurs visible from Hawaii. A second close approach takes place on March 29, with Vesta half a degree above the northern limb of the moon. There is another occultation visible from parts of the Pacific well to the north of NZ.
-- Brian Loader
6. 2020 Beatrice-Hill-Tinsley Lectures
The RASNZ Lecture Trust is pleased to announce that the 2020 Beatrice-Hill-Tinsley lecturer is Professor Anna Scaife, Professor of Radio Astronomy at the University of Manchester and Head of the Jodrell Bank Centre for Astrophysics Interferometry Centre of Excellence.
Affiliated Societies are invited to host Professor Scaife during the lecture series which will be occurring in the three weeks prior to the 2020 RASNZ conference in early May. Expressions of interest should be sent to the lecture trust secretary at LectureTrust@rasnz.org.nz at the earliest opportunity before February 28th.
For general information about the BHT lectures see
https://www.rasnz.org.nz/rasnz/beatrice-hill-tinsley-lectures
-- From https://www.rasnz.org.nz/
7. 2020 Conference and RASNZ Centenary
It is a pleasure to announce that the next conference of the Royal Astronomical Society of New Zealand (RASNZ) will be held at the Wharewaka Function Centre on Wellington waterfront over the weekend of 8 - 10 May 2020. The Wellington Astronomical Society is hosting the Conference.
This year is the 100th anniversary of the formation of the Society and to honour this special occasion we will be welcoming four invited speakers. They will be Dr Dom Pesce (Black Hole Initiative, Harvard University), Professor Anna Scaife and Dr Rene Breton (Manchester University/Jodrell Bank) and Dr Chris Lintott (Oxford University). This year the Fellows´ Lecture will be given by long standing Society member and past president John Drummond. Titles and abstracts for these talks will be released when they are available.
As the programme will commence at the earlier than usual time at 1pm on Friday we encourage as many as possible to make their travel arrangements to arrive in the city during the morning.
The conference will be preceded by a Dark Sky Workshop on the morning of
Thursday 7 May. The workshop will consist of short talks on relevant key local and international dark sky updates and discussion/demonstration on topics such as sky quality measurements and dark sky friendly lighting.
The RASNZ website now has available the conference brochure, on-line registration (and downloadable form) and paper submission (via the registration page). See it all here: http://www.rasnz.org.nz/groups-news-events/rasnz-conference.
Please consider participating in this Conference as RASNZ celebrates its centenary - we look forward to seeing you there.
-- Glen Rowe, Chair, Standing Conference Committee.
8. Call for Papers for 2020 RASNZ Conference
The RASNZ Standing Conference Committee (SCC) invites and encourages anyone interested in New Zealand astronomy to submit oral or poster papers, with titles and abstracts due by 1 April 2020 or until such time as the SCC deems the conference programme to be full. The link to the paper submission form can be found on the RASNZ Conference website http://rasnz.org.nz/groups-news-events/rasnz-conference. Please note that you must be registered for the conference to give an oral presentation, and for your convenience a link has been provided if you wish to do this when you submit a paper.
We look forward to receiving your submissions and seeing you at the conference. Please feel free to forward this message to anyone who may find it of interest.
For further information on the RASNZ Conference, registration details and associated events please visit the conference website at http://rasnz.org.nz/groups-news-events/rasnz-conference.
-- Warwick Kissling, RASNZ Standing Conference Committee
9. Star Parties in 2020
The following star parties are planned for 2020:
Northern Star Party, Waharau, March 20-22. See Item 2, above.
Stargazers Getaway 2020 Camp Iona, Friday September 18th to Sunday 20th. This is New Moon, so we are targeting this weekend for dark skies! See
https://www.facebook.com/events/943327669369996/
NACAA: The 29th NACAA conference will be held in the NSW (Australia) regional city of Parkes (where the world-famous Parkes Radio Telescope is) over the 2020 Easter weekend, Friday April 10th – Monday 13th. For more details see http://nacaa.org.au/2020/about
-- Mostly from 'Keeping in Touch' #34, 27th Sept 2019.
10. Variable Star News
Recent Publication
Studies by some Variable Star South (VSS) workers on a four star system has been featured in an AAVSO Community Newsletter, email 4th February 2020. The paper combines a number of studies on the variable QZ Carinae which consists of two binary pairs. To complicate the analysis one of the stars exhibits small light variations. One of the components is a massive star. The publication reference is Blackford M. et al (2020) JAAVSO 48 (No 1). QZ Car was discovered in 1971 by Brian Marino and Stan Walker of Auckland Observatory.
There are six VSS authors, M Blackford, S Walker, E Budding, G Bolt, D Blane, T Bohlsen; additionally there are six authors from the BRITE team. The BRITE-Constellation collaboration (advised in AAVSO posting 2 Oct 2016) combines satellite observations and ground-based photometric and spectrographic measurements on selected stellar targets.
The published work focusses on the period of the two binary pairs, one of which is an eclipsing system. Such systems can help determine masses of the component stars. The posting by the Journal Editor noted that the determination of exact masses of hot massive stars is difficult and the work undertaken will assist in establishing the values in this system.
Betelgeuse.
Have you been looking at the constellation Orion recently? To me it looks unbalanced - the bright star at the hunter’s shoulder (Betelgeuse) no longer balances the diagonally opposite bright blue star Rigel at his left foot. The start of the deep fade of Betelgeuse caused a storm of publicity and the steep decline has captured a lot of interest. As at the 18th of February it is at about V-filter magnitude 1.8, a far deeper minimum than the cycles immediately beforehand (decrease in magnitude approximately 0.5). Perhaps the star has entered a new pulsation mode, but other explanations are possible. It does appear that the light intensity is plateauing so make sure you see this new view of the constellation before the star recovers its usual brightness of about V magnitude 0.5. There is still plenty of analysis to go before we complete this story.
-- Alan Baldwin
11. Dark Energy Explained?
Cosmologists don’t enter their profession to tackle the easy questions, but there is one paradox that has reached staggering proportions.
Since the big bang, the universe has been expanding, but the known laws of physics suggest that the inward tug of gravity should be slowing down this expansion. In reality, though, the universe is ballooning at an accelerating rate.
Scientists have come up with a name – dark energy – for the mysterious agent that is allowing the cosmos to expand so rapidly and which is estimated to account for 70% of the contents of the universe. But ultimately nobody knows what the stuff actually is.
“It’s the big elephant in the room,” says Prof Claudia de Rham, a theoretical physicist at Imperial College. “It’s very frustrating.”
Change could be afoot. De Rham has pioneered a radical theory that could hold the key to why the universe is expanding faster and faster and explain the nature of dark energy. The theory, known as massive gravity, modifies Einstein’s general relativity, positing that the hypothetical particles (gravitons) that mediate the gravitational force themselves have a mass. In Einstein’s version, gravitons are assumed to be massless.
If gravitons have a mass, then gravity is expected to have a weaker influence on very large distance scales, which could explain why the expansion of the universe has not been reined in. “One possibility is that you may not need to have dark energy – or rather, gravity itself fulfils that role,” says De Rham.
The work marks a breakthrough in a century-long quest to build a working theory of massive gravity. Despite successive efforts, previous versions of the theory had the unfortunate feature of predicting the instantaneous decay of every particle in the universe – an intractable issue that mathematicians refer to as a “ghost”. “Very clever people had worked on this and the arguments were very compelling,” says De Rham. “People thought it would be impossible to make it work.”
But in 2011, when De Rham and her collaborators, Gregory Gabadadze from New York University and Andrew Tolley from Imperial College London, published a landmark paper on massive gravity, the response was swift and hostile.
In the end, the theory stood up and has been gaining traction in the past decade. “That’s what science does. At the end there’s a result based on maths and logic,” De Rham says. “If one is equal to one, we can all agree on that. Maths don’t lie.”
In the latest acknowledgement of the breakthrough, De Rham was recipient of the $100,000 (£75,000) Blavatnik Award for Young Scientists, two years after winning the Adams prize, one of the University of Cambridge’s oldest and most prestigious awards.
De Rham is quick to point out that at this stage, massive gravity is still just a theory. Mathematically it checks out, but we don’t know whether it reflects empirical reality. But with the advent of gravitational wave astronomy, it will be possible to test predictions of the theory over the next decade and beyond.
“It would be amazing if it was shown to be right,” she says. “That may or may not happen, but what will happen is that we’ll have a much better fundamental understanding of gravity and that’s just something so deep, it’s one of the big questions today.”
De Rham’s more recent work covers other aspects of gravity. She is interested in the speed of gravity, which has never been directly measured and which theory predicts could in some circumstances be faster than light. She is also investigating whether gravity, like light, moves at different speeds through different materials. If it does, gravitational rainbows would exist that might be viewable with gravitational wave telescopes.
As a new generation of gravitational wave observatories, such as ESA’s space-based observatory, Lisa, start gathering faint signals from the cosmos in the next decade, De Rham hopes to close in on some answers. “It’s going to be such a high level of science that we can do,” says De Rham. “It’s beautiful.”
-- Abridged from Hannah Devlin's article in The Guardian, 25 January 2020. See the original at
https://www.theguardian.com/science/2020/jan/25/has-physicists-gravity-theory-solved-impossible-dark-energy-riddle
12. Stars in the Magellanic Stream
Ground- and space-based observations have revealed a group of stars at the head of the giant stream of gas burrowing its way through the Milky Way. A newfound cluster of young stars sits on the periphery of the Milky Way. These stars probably formed from material originating from neighbouring dwarf galaxies called the Magellanic Clouds.
The collection of young stars in a surprising location — deep in the halo of old stars surrounding the Milky Way. Adrian Price-Whelan (Flatiron Institute) found the loose cluster while digging through the second data release from the European Gaia mission. Gaia is currently mapping the motions and locations of more than 1 billion stars, extending astronomers’ reach from just a few hundred light-years to most of our galaxy. The newly found stars clearly move together as a set. At 116 million years old, the cluster is young and also fairly lightweight, similar to the Pleiades in both age and mass.
But, unlike the Pleiades, these stars lie far away: some 94,000 light-years, roughly 200 times farther from Earth than the iconic Seven Sisters. They’re also spread out, spanning some 1,600 light-years. That means they’re probably no longer gravitationally bound together and therefore not a cluster in the technical sense of the word.
By rights, the stars shouldn’t be out there. There’s not much star-making gas in the Milky Way’s halo and the gas that is there is too hot and spread out to collapse to create new suns. What little cool stuff there is is almost entirely in the Magellanic Stream, a vast ribbon of (mostly) hydrogen gas traveling with the Large and Small Magellanic Clouds through our galaxy’s outer regions. And the stars appear to be sailing at the head of that ribbon of gas.
To confirm the stars’ location, Price-Whelan, David Nidever (Montana State University), and their colleagues took spectra of 28 of the brightest stars in the group. The measurements confirmed the stars’ ages and that they have fairly pristine compositions, polluted with only small quantities of heavy elements. The compositions look nothing like stellar new-borns in the Milky Way, but they match the gas in the stream’s leading arm. The stars’ velocities also line up with that of the stream.
Combined, the various observations led the team to conclude these stars likely formed from the gas at the head of the Magellanic Stream, Price-Whelan and Nidever reported at the winter American Astronomical Society meeting in Honolulu. The results also appear in two papers in the Astrophysical Journal.
Observers have been looking for stars associated with the Magellanic Stream for decades, explains Jeremy Bailin (University of Alabama). Astronomers don’t know how far away the stream is because it’s hard to determine distances to a cloud of hydrogen gas. But stars are different — and we can learn all sorts of cool things with stars.
The difficulty with distance might explain why the new cluster’s estimated distance is roughly half the number that’s often used for the Magellanic Stream. If the stream really is that much closer, it could mean that its gas — and the gas of the Magellanic Clouds — will dump into the Milky Way and spur starbirth sooner than astronomers predicted.
The stars lie at the leading edge of the stream, though, not in it. The team thinks this offset exists because, as the stream ploughs through the hot gas in the halo, it feels a drag. The stars don’t, however. Over time, the gas would slow down and fall behind. Indeed, the stars’ ages match when the stream passed through our galaxy’s outer disk in the recent past. That passage could have compressed the stream’s gas, spurring starbirth.
-- From Camille M. Carlisle's article on Sky & Telescope's webpage at
https://www.skyandtelescope.com/astronomy-news/baby-stars-found-ancient-part-milky-way-galaxy/
For more on Gaia's results see
https://www.skyandtelescope.com/astronomy-news/gaia-maps-1-7-billion-stars-widens-cosmic-census/
13. Big New Solar Telescope
First images from the U.S. National Science Foundation's Daniel K. Inouye Solar Telescope reveal unprecedented detail of the Sun's surface and preview the world-class products to come from this preeminent 4-meter solar telescope. NSF's Inouye Solar Telescope, on the summit of Haleakala, Maui, in Hawai'i, will enable a new era of solar science and a leap forward in understanding the Sun and its impacts on our planet.
Activity on the Sun, known as space weather, can affect systems on Earth. Magnetic eruptions on the Sun can impact air travel, disrupt satellite communications, and bring down power grids, causing long-lasting blackouts and disabling technologies such as GPS.
The first images from the Inouye Solar Telescope show a close-up view of the Sun's surface, which can provide important detail for scientists. The images show a pattern of turbulent "boiling" plasma that covers the entire Sun. The cell-like structures -- each about 1000 km across -- are the signature of violent motions that transport heat from the inside of the Sun to its surface. That hot solar plasma rises in the bright centres of "cells," cools, then sinks below the surface in dark lanes in a process known as convection.
The telescope will be able to map the magnetic fields within the Sun's corona, where solar eruptions occur that can impact life on Earth. This telescope will improve our understanding of what drives space weather and ultimately help forecasters better predict solar storms.
The Sun is our nearest star -- a gigantic nuclear reactor that burns about 5 million tons of hydrogen fuel every second. It has been doing so for about 5 billion years and will continue for the other 4.5 billion years of its lifetime. All that energy radiates into space in every direction. The tiny fraction that hits Earth makes life possible. In the 1950s, scientists figured out that a solar wind blows from the Sun to the edges of the solar system. They also concluded for the first time that we live inside the atmosphere of this star. But many of the Sun's most vital processes continue to confound scientists.
"On Earth, we can predict if it is going to rain pretty much anywhere in the world very accurately, and space weather just isn't there yet," said Matt Mountain, president of the Association of Universities for Research in Astronomy (AURA), which manages the Inouye Solar Telescope. "Our predictions lag behind terrestrial weather by 50 years, if not more. What we need is to grasp the underlying physics behind space weather, and this starts at the Sun, which is what the Inouye Solar Telescope will study over the next decades."
The motions of the Sun's plasma constantly twist and tangle solar magnetic fields. Twisted magnetic fields can lead to solar storms that can negatively affect our technology-dependent modern lifestyles. During 2017's Hurricane Irma, the National Oceanic and Atmospheric Administration reported that a simultaneous space weather event brought down radio communications used by first responders, aviation and maritime channels for eight hours on the day the hurricane made landfall.
Finally resolving these tiny magnetic features is central to what makes the Inouye Solar Telescope unique. It can measure and characterize the Sun's magnetic field in more detail than ever seen before and determine the causes of potentially harmful solar activity.
Better understanding the origins of potential disasters will enable governments and utilities to better prepare for inevitable future space weather events. It is expected that notification of potential impacts could occur earlier -- as much as 48 hours ahead of time instead of the current standard, which is about 48 minutes. This would allow more time to secure power grids and critical infrastructure and to put satellites into safe mode.
To achieve the proposed science, this telescope required important new approaches to its construction and engineering. Built by NSF's National Solar Observatory and managed by AURA, the Inouye Solar Telescope combines a 4-metre mirror -- the world's largest for a solar telescope -- with unparalleled viewing conditions at the 3,000-metre Haleakala summit.
Focusing 13 kilowatts of solar power generates enormous amounts of heat -- heat that must be contained or removed. A specialized cooling system provides crucial heat protection for the telescope and its optics. More than seven miles of piping distribute coolant throughout the observatory, partially chilled by ice created on site during the night.
The dome enclosing the telescope is covered by thin cooling plates that stabilize the temperature around the telescope, helped by shutters within the dome that provide shade and air circulation. The "heat-stop" (a high-tech, liquid-cooled, doughnut-shaped metal) blocks most of the sunlight's energy from the main mirror, allowing scientists to study specific regions of the Sun with unparalleled clarity.
The telescope also uses state-of-the-art adaptive optics to compensate for blurring created by Earth's atmosphere. The design of the optics ("off-axis" mirror placement) reduces bright, scattered light for better viewing and is complemented by a cutting-edge system to precisely focus the telescope and eliminate distortions created by the Earth's atmosphere. This system is the most advanced solar application to date.
NSF's new ground-based Inouye Solar Telescope will work with space-based solar observation tools such as NASA's Parker Solar Probe (currently in orbit around the Sun) and the European Space Agency/NASA Solar Orbiter. The three solar observation initiatives will expand the frontiers of solar research and improve scientists' ability to predict space weather.
-- From a US National Science Foundation press release forwarded by Karen Pollard. For images see https://www.nso.edu/inouye-solar-telescope-first-light/
14. How to Join the RASNZ
RASNZ membership is open to all individuals with an interest in
astronomy in New Zealand. Information about the society and its
objects can be found at
http://rasnz.org.nz/rasnz/membership-benefits
A membership form can be either obtained from treasurer@rasnz.co.nz or
by completing the online application form found at
http://rasnz.org.nz/rasnz/membership-application
Basic membership for the 2020 year starts at $40 for an ordinary
member, which includes an electronic subscription to our journal
'Southern Stars'.
15. Gifford-Eiby Lecture Fund
The RASNZ administers the Gifford-Eiby Memorial Lectureship Fund to
assist Affiliated Societies with travel costs of getting a lecturer
or instructor to their meetings. Details are in RASNZ By-Laws Section
H and at http://rasnz.org.nz/rasnz/ge-fund
The application form is at
http://rasnz.org.nz/Downloadable/RASNZ/GE_Application2019.pdf
16. Quotes
"The greatest threat to our planet is the belief that someone else will save it." - Explorer Robert Swan quoted in 'NZ Listener' 22 February 2020.
"Defending light pollution with the argument that we need light to see at night is like defending unending rock festivals with the argument that we need sound to communicate. It's not a yes/no question, but a question of how much, where, and when." -- Annette Krop-Benesch in La Palma #lightpollution retweeted.
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
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