March 2021 News and research
Astronomy_News_20_03_2021
This months research Papers 20_03_2021
RASNZ_20_03_2021
Further links and discussion can be found at the groups/links below
Astronomy in New Zealand - Facebook
https://www.facebook.com/groups/5889909863/
Astronomy in New Zealand - Groups.io
https://groups.io/g/AstronomyNZ
Google Group
https://groups.google.com/g/nzastrochat
Astronomy in Wellington
https://www.facebook.com/groups/11451597655/
Blogger Posts
http://laintal.blogspot.com/
Reddit
https://www.reddit.com/user/Edwin_Rod_NZ
Quaroa
https://www.quora.com/q/astronomyinnewzealand
Twitter
https://twitter.com/Laintal
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Research papers
Spin state and moment of inertia of Venus
https://arxiv.org/abs/2103.01504
Implications of an improved water equation of state for water-rich planets
https://arxiv.org/abs/2103.01410
Concepts for future missions to search for technosignatures
https://arxiv.org/abs/2103.01536
Generalized Stoichiometry and Biogeochemistry for Astrobiological Applications
https://arxiv.org/abs/2011.02425
The future lifespan of Earth's oxygenated Atmosphere
https://arxiv.org/abs/2103.02694
Longevity is the key factor in the search for technosignatures
https://arxiv.org/abs/2103.02923
A new paper on interstellar objects:
Interstellar Objects in the Solar System: 1. Isotropic Kinematics from the Gaia Early Data Release 3
https://arxiv.org/abs/2103.03289
evidence for an extended dust disk and constraints on the presence of giant planets in the Habitable Zone of ß Leo
https://arxiv.org/abs/2103.03268
round-based measurements of the precipitable water vapor in the Atacama Desert
https://arxiv.org/abs/2103.03917
The SPHERE infrared survey for exoplanets
https://arxiv.org/abs/2103.04366
Ethane clathrate hydrate infrared signatures for solar system remote sensing
https://arxiv.org/abs/2103.04928
Water on Hot Rocky Exoplanets
https://arxiv.org/abs/2103.07753
Life as the Only Reason for the Existence of N2-O2-Dominated Atmospheres
https://arxiv.org/abs/2103.09264
Circumbinary habitable zones in the presence of a giant planet
https://arxiv.org/abs/2103.09201
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Interesting News items
A Super-Earth Is Discovered Which Can Be Used To Test Planetary Atmosphere Models
http://astrobiology.com/2021/03/a-super-earth-is-discovered-which-can-be-used-to-test-planetary-atmosphere-models.html
Oumuamua
http://spaceref.com/interstellar/interstellar-object-oumuamua-is-likely-a-piece-of-a-pluto-like-planet.html
Interesting reading
https://www.stuff.co.nz/science/124597306/how-wind-changes-around-zealandia-may-have-farreaching-consequences-for-global-climate
Our first interstellar visitor 'Oumuamua may be an ice chunk blasted off an alien Pluto
https://www.syfy.com/syfywire/our-first-interstellar-visitor-oumuamua-may-be-an-ice-chunk-blasted-off-an-alien-pluto
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Updates from Andrew B,
Mars.
Very easy to forget given the current and rightfully justified attention to the Mars Perseverance Rover that there are also two other long serving craft on the surface of Mars, Mars Science Laboratory Curiosity Rover (August 2012) and this one, the Mars InSight Lander / Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (November 2018).
Mars InSight Lander is about 3,452 KM / 2,145 miles from Mars Perseverance Rover.
Sunday 14th March 2021. Sol: 816.
From 15:30 to 15:38 Hrs LMST = Local Mars Standard Time in western Elysium.
These from the Instrument Deployment Camera with a 45 degree wide view on the robotic arm and the Instrument Context Camera with a 120 degree wide view mounted on the south facing lander deck.
Elysium Planitia. Elysium Quadrangle.
These images document the next phase of the Mars InSight mission, the covering over of the leads to the SEIS / Seismic Experiment for Interior Structure, the Seisomometer. This will help increase the signal to noise ratio in detecting Marsquakes. The SEIS has been hugely successful in determining that Mars is still seismically active, certainly not a geologically dead planet, far from it. Also the lead to the HP3 / Heat Flow and Physical Properties Package will also be covered over.
Here a scoop load of duricrust was dropped onto the dome shaped Wind & Thermal Shield and slid off in the 37.8 % Earth gravity on Mars.
This was deliberate as the duricrust covering that end of the lead would cover it more softly than if it was just dropped. Further along the lead, it is less of a problem as the scoop can be lower. Left a nice clean section where the dust slowly falling out of the martian atmosphere that had settled was swept off.
So what will happen will be that the scoop on the robotic arm will scoop up duricrust and then cover the lead. This will minimize vibrations from the martian wind despite the atmospheric pressure here barely as dense as Earth's atmosphere is at about 35 KM / 22 miles above sea level.
The Mars InSight lander will also be put on a reduced workload over the coming northern hemisphere Martian Winter. The solar arrays are becoming increasingly dusty, reducing the power output as well as lowering temperatures. At night the temperatures will drop to below minus 100 Celsius / minus 148 Fahrenheit. The Seis and the cameras will still collect data. This will help the InSight Lander to complete the extended mission, which will vastly increase the scientific value of this hugely successful lander.
Text: Andrew R Brown.
NASA / JPL-Caltech. Mars InSight.
Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.
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RASNZ
Royal Astronomical Society of New Zealand
eNewsletter: No. 243, 20 March 2021
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. UK Meteorite a Rare Type
2. Reminders for Members
3. The Solar System in April
4. Northern Star Party – Waharau - April 9-11
5. International Dark Sky Week - April 5-12
6. IAU Astrophotography contest - Close April 15
7. Variable Stars News
8. Aotearoa Astrotourism Academy -- September 10-12
9. Cosmic neutrino from Star-Swallowing Black Hole
10. Antikythera Mechanism Solved?
11. How to Join the RASNZ
11. Gifford-Eiby Lecture Fund
12. Quotes
1. UK Meteorite a Rare Type
A lump of a rare meteorite that lit up the night sky over the UK and northern Europe last week has been recovered from a driveway in Gloucestershire.
The fragment, weighing nearly 300 grams, and other pieces of the space rock were located after scientists reconstructed the flight path of the fireball that unleashed a sonic boom as it tore across the sky shortly before 10pm UK time on Sunday 28 February.
The black chunk of rock, a carbonaceous chondrite never seen before in the UK, thumped on to a driveway in the Cotswolds town of Winchcombe, scientists at the Natural History Museum in London said, adding that further fragments were retrieved nearby.
Ashley Green, a scientist at the museum, said it was “a dream come true” to be one of the first people to see and study a meteorite that had been recovered almost immediately after coming down.
Footage of the bright streak captured by the public, and a camera network operated by the Natural History Museum’s UK Fireball Alliance, helped researchers calculate that the meteor had spent most of its orbit between Mars and Jupiter before it ploughed into Earth’s atmosphere.
Computer modelling revealed that any surviving remnants of the meteor were likely to come down as meteorites north of Cheltenham, but with the space rock travelling at about 13 km per second the precise location was hard to predict.
What is likely to become known as the Winchcombe meteorite is the first to be recovered in the UK in 30 years and the first carbonaceous chondrite found in the country to date. Of about 65,000 known meteorites on Earth, only 51 are carbonaceous chondrites. A mixture of minerals and organic compounds, including the amino acid building blocks of life, they are considered the most primitive and pristine materials in the solar system.
Since the meteorite was discovered on Wednesday, Dr King has been advising on the care and carriage of the rock back to London, where it will be officially classified and studied further to understand its significance.
Richard Greenwood, a planetary scientist at the Open University, said he was “in shock” when he saw the lump of rock. “It’s emotional being the first one to confirm to the people standing in front of you that the thud they heard on their driveway overnight is in fact the real thing,” he said.
More fragments may yet be found as black stones, piles of tiny rocks, or even dust, the scientists believe. People in the area who find potential remnants are urged to take a photo and record the location before collecting a sample in aluminium foil and contacting the Natural History Museum.
-- See the original article Ian Sample, with photos and videos, at
https://www.theguardian.com/science/2021/mar/09/rare-meteorite-chunk-traced-by-scientists-to-gloucestershire-driveway
2. Reminders for Members
2021 RASNZ Conference in Wellington
The 2021 RASNZ conference is planned to be held in Wellington from Friday
9th until Sunday 11th July 2021. Come along for this special 100th anniversary conference! A Dark Skies workshop is also planned. Keep an eye on the RASNZ webpage for details as they evolve, https://www.rasnz.org.nz/ .
RASNZ 2021 Subscriptions Due
The 2021 RASNZ subscriptions are due on the 1st of January 2021. See -
https://www.rasnz.org.nz/rasnz/payments-and-donations .
For bank transfer payments the details are
ASB Bank - Riccarton Branch
Account name RASNZ
Account number 12-3147-0384735-00
If the payment covers more than membership then please note that.
Subscription rates were not correctly shown on the payments page of the
RASNZ Website following the non-publication of the Astronomy Year Book for 2021. This has meant some people will have overpaid if they ordered a
copy with their subscription. If so please email: treasurer@rasnz.org.nz
with details of the payment and your bank details.
Southern Stars
Got an interesting astronomical story, area of astronomical research or
Article to share? Southern Stars editor Bob Evans would love to hear from you! He´s always keen to see more articles in Southern Stars. Southern Stars is the journal of the RASNZ and an excellent forum to publish within. Write to bevans@xtra.co.nz
-- John Drummond, RASNZ President.
3. The Solar System in April
NZDT comes to an end at 3am on Sunday 4 April. NZ then reverts to NZST, 12 hours ahead of UTC. Consequently dates and times shown are NZDT (UT + 13 hours) up to early Sunday morning on April 4. For the rest of April NZST applies. 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 APRIL, Rise & Set, Magnitude & Constellation
Apr 1 NZDT Apr 30 NZST
Mag Cons Rise Set Mag Cons Rise Set
SUN -26.7 Psc 7.33am 7.14pm -26.7 Ari 7.04am 5.31pm
Merc -0.5 Aqr 6.08am 6.46pm -1.2 Ar1 8.11am 5.59pm
Venus -4.0 Psc 7.40am 7.23pm -3.9 Ari 7.50am 5.57pm
Mars 1.3 Tau 1.09pm 10.15pm 1.6 Gem 11.35am 8.35pm
Jup -2.1 Cap 3.26am 5.19pm -2.2 Aqr 12.57am 2.38pm
Sat 0.8 Cap 2.24am 4.45pm 0.7 Cap 11.39pm 1.56pm
Uran 5.9 Ari 9.55am 8.22pm 5.9 Ari 7.09am 5.33pm
Nep 8.0 Aqr 5.49am 6.28pm 7.9 Aqr 3.00am 3.36pm
Pluto 14.6 Sgr 1.06am 4.03pm 14.5 Sgr 10.13pm 1.10pm
April 1 NZDT April 30 NZST
Twilights morning evening morning evening
Civil: start 7.09am, end 7.40pm start 6.38am, end 5.58pm
Nautical: start 6.37am, end 8.12pm start 6.05am, end 6.30pm
Astro: start 6.04am, end 8.44pm start 5.33am, end 7.02pm
APRIL PHASES OF THE MOON, times NZST & UT
Last quarter: Apr 4 at 10.03pm (10:03 UT)
New Moon: Apr 12 at 2.31pm (02:31 UT)
First quarter: Apr 20 at 6.59pm (06:59 UT)
Full Moon: Apr 27 at 3.32pm (03:32 UT)
THE PLANETS in APRIL
MERCURY starts April as a morning object, rising 85 minutes before the Sun on the 1st. Over the next 18 days the planet closes in on the Sun until mid April, superior conjunction being on the 19th. At its closest at 1pm NZST Mercury will be 20 arc minutes south, above, the Sun, i.e. less than a solar diameter but, of course, completely unobservable. It becomes a nominal evening object for the rest of the month but is too close to the Sun for observation.
VENUS is also too close to the Sun for observation and is close to Mercury towards the end of April: they are just over a degree apart on the 26th.
MARS sets approximately 3 hours after the Sun all month, so it is visible in the early evening sky. The planet moves from Taurus to Gemini on the 24th. It is well north of the celestial equator so low in southern skies. The crescent moon will be about 3° from Mars at 7pm on the 17th. A few hours later the moon will occult Mars, an event visible from equatorial Africa.
JUPITER and SATURN move further up into the morning sky with Saturn rising just before midnight by the 30th. Jupiter rises at 1am. The crescent moon is a few degrees from Saturn on the morning of April 7 and a similar distance from Jupiter the next morning.
PLUTO, is also a morning object, still in Sagittarius. It rises more than an hour before Saturn.
URANUS is at conjunction with the Sun at the end April. Like Mercury and Venus it will be unobservable during the month. Venus passes Uranus on the 23rd when the two will be only a quarter degree apart with Venus to the south of Uranus. The following day Mercury will be three quarters of a degree to the north of Uranus.
NEPTUNE moves up into the morning sky, rising 4 hours before the Sun by April 30.
POSSIBLE BINOCULAR ASTEROIDS in April
April 1 NZDT April 30 NZST
Mag Cons transit Mag Cons transit
(1) Ceres 9.0 Cet 1.50pm 9.1 Psc 11.34am
(4) Vesta 6.5 Leo 11.37pm 7.0 Leo 8.37pm
CERES is at conjunction with the Sun on the 7th so too close to the Sun for observation all month.
VESTA, an evening object rises nearly 2 hours before the Sun sets on the 1st and over 3 hours before on the 30th. The asteroid, in Leo, is stationary on April 22.
-- Brian Loader
4. Northern Star Party – Waharau - April 9-11
The Auckland Astronomical Society's Northern Star Party (Dark Sky Weekend) will be at Waharau Regional Park. April 9th to 11th 2021.
It is also open to non-members to attend. It’s a great fun weekend.
The Auckland Astronomical Society’s Waharau Dark Sky Weekend (2021 Northern Star Party – Dark Sky Weekend) is held at Waharau Regional Park 1748 East Coast Rd, Orere Point, Whakatiwai 2473 (about 1 hour's drive from central Auckland), starting on Friday 9th April at 5pm and ending Sunday 11th November at 11am.
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 through 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. The society has telescopes available for hire. Contact Steve Hennerley on 027 245 6441 or Darren Woodley 021 776 481 or email: rental@astronomy.org.nz to get these. Book now to avoid disappointment!
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 if appropriate on Saturday.
Price:
AAS Member earlybird $20.00.
AAS Member standard $30.00
Non-member earlybird $40.00.
Non-member standard $50.00
Earlybird applies for payments received by Friday 26th March.
This price includes bunk bed type accommodation. To book please pay the amounts as set out above into the Auckland Astronomical Society Inc ASB bank account: 12-3061-0321397-00 with the notation “Waharau” and your name. Then email Gavin Logan: gavinlgn@gmail.com giving the names of the people attending.
There is an event limit of 65. The last Waharau Star Party sold out. Booking will be confirmed once payment has been made.
-- From the Auckland Astronomical Society's Journal, February 2021.
5. International Dark Sky Week - April 5-12
Steve Butler passed along this email from the International Dark Sky Association (IDA).
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Artificial light at night has revolutionized how we live and work
outdoors, but it has come at a price. When used indiscriminately,
outdoor lighting can disrupt wildlife, impact human health, waste money
and energy, contribute to climate change, and block our view of the
universe.
Recognizing the continued challenges posed by the global COVID-19
pandemic, the International Dark-Sky Association has organized
International Dark Sky Week (IDSW) 2021, April 5-12, to
#DiscoverTheNight. During International Dark Sky Week, IDA aims to
connect an international audience with the dark sky movement, discover
the night wherever they may live, and promote win-win solutions that
allow people to appreciate dark, star-filled skies.
To create an engaging event inclusive of geography and representative of
the IDSP and advocacy communities’ diverse work, we at IDA are asking
for your support. While all known events happening for IDSW 2021 are to
be shared, IDA wants to specifically highlight your unique story regarding how you’ve celebrated and protected the night sky as a benefit to all living things. Please fill out the linked form
<https://docs.google.com/forms/d/e/1FAIpQLSevIDElxL0Kr4vS7SGdch37WIjWACT_4jrYw8cYFXHtAdcIKA/viewform> to provide an overview of your efforts. Your response will be used to create an interactive map on idsw.darksky.org <http://idsw.darksky.org>.
Optionally, if you have any videos which show your efforts as an IDSP,
please send videos or video links directly to the IDSW point of contact:
Lauren Scorzafava <mailto:lauren@darksky.org>at lauren@darksky.org
<mailto:lauren@darksky.org>.
Additionally, if you are planning to create a Facebook Event for your
event and would like IDA to co-host, please set IDA as a co-host when
creating your event and email Lauren (lauren@darksky.org
<mailto:lauren@darksky.org>) with the name of the event and a link so
that we can be sure to accept the request in order to amplify your event.
We, at IDA, hope you can join us this International Dark Sky Week 2021
to learn more about and support the movement while discovering the night
where you live. Thank you for your continued commitment, and if you have
any questions about being a highlighted site or IDSW generally, please
contact IDA’s Communications Associate and IDSW point of contact: Lauren
Scorzafava <mailto:lauren@darksky.org>at lauren@darksky.org
<mailto:lauren@darksky.org>.
Best,
Adam M. Dalton, IDSP Program Manager.
6. IAU Astrophotography contest - Close April 15
Are you an astrophotographer – and keen on supporting astronomy education? Then this contest is for you: The IAU's Office of Astronomy for Education (OAE) is running an astrophotography contest until April 15 2021. Besides receiving cash prizes, the winning images will be made available as Open Educational Resources for teachers and learners world-wide.
Astronomy education is a powerful tool to teach students about the place of our planet, and ourselves, in the universe – and a gateway science to the STEM subjects (science, technology, engineering, mathematics). One of the OAE's goals is to provide astronomy educators worldwide with a basic collection of high quality educational resources. While many useful images are already available for public use, we have identified a number of astronomy-related themes where we think educators could use support.
Participants can submit images in the following categories: star trails, meteor showers, comets, total lunar eclipses, light pollution, aurorae (still images and time-lapses), wide star fields, Sun/Moon haloes, and time-lapses of Galilean moons orbiting around Jupiter. Submissions will be evaluated by an international panel of astrophotographers and astronomy educators. Apart from aesthetic and technical criteria, the jury will carefully consider the educational value of each entry in the context of primary and secondary school teaching.
There will be three winning entries for each category, which will be awarded with cash prizes of 750, 500 and 250 Euros for the first, second, and third prizes, respectively. All winning entries are published in the OAE's astronomy education resources collection under a Creative Commons Attribution (CC BY) 4.0 International Licence (note that the authors will still retain the copyright to their images). See
https://creativecommons.org/licenses/by/4.0/
Before submitting your entries, please read carefully the competition rules, which you can find at https://www.haus-der-astronomie.de/3984845/oae_astrophotography_contest_rules.pdf
You can submit your entries at
https://docs.google.com/forms/d/e/1FAIpQLSfR9Wnm6li5dveq5Xq1VZ0pqf_nAUs60iAdNfp6c491hSEdBQ/viewform
For any queries regarding the competition, please contact oae-astrophoto (at) astro4edu.org.
-- From https://www.haus-der-astronomie.de/oae/collaborate/astrophotography-contest
7. Variable Star News
Southern variables are the subject of two current AAVSO Alert Notices. Links can be found in the “AAVSO at a Glance” section on their home page. These campaigns offer southern amateurs the opportunity to contribute valuable data to studies by professional astronomers.
ASASSN-21co
Alert Notice 732 requests observations of eclipsing binary ASASSN-21co which has a period of ~11.9 years and V magnitude of ~11.7 at maximum. It is currently undergoing an eclipse which started between 2021 February 10 and 12 and is expected to last ~80 days. Colour photometry (all filters) is requested, as is spectroscopy of all resolutions. Visual observations are welcome. Please continue to monitor ASASSN-21co at least until after it has returned to maximum. ASASSN-21co is located at RA 18 17 51.54, Dec -58 07 49.3 (J2000) and is currently a predawn object, transiting around 8am.
TW Hya
Alert Notice 733 calls for ground based CCD multi-filter photometry in support of Hubble Space Telescope (HST) and Transiting Exoplanet Survey Satellite (TESS) observations of the 10 million year old K7 pre-main sequence star TW Hya. It is fairly bright, with a mean V ~ 11, and a historical range from 10.6 to 11.3. The typical day-to-day range of variability is +/- 0.1 mag. TW Hya is located at RA 11:01:51.9, Dec -34:42:17.0 (J2000), and at this time of year transits around midnight.
TESS will observe this part of the sky nearly continuously for 27 days, from 7 March through 2 April, with a 10 minute cadence. HST will record UV spectra during that time. TESS data, both in terms of length of coverage and data quality, cannot be matched from the ground, but TESS is a single channel photometer operating in the red. Therefore ground-based optical photometry is needed to place the TESS magnitudes in context.
The campaign aims to determine if:
- stellar variations are due to enhanced accretion events or long-lived flares, in which case the star should become bluer, or
- are they due to variable circumstellar extinction, in which case the star will become redder, or
- are they due to obscuration of the photosphere by optically-thick irregularities in the circumstellar disk, in which the colour should not change.
Analysis of Eclipsing Binaries
Dr. Bob Nelson presented a workshop titled “Times of Minimum Analysis for Eclipsing Binaries” at the 2018 Symposium of the Society for Astronomical Sciences. Videos are now freely available online and I recommend them to anyone with an interest in accurately determining the timing of eclipsing binary minima. Part 1 https://youtu.be/KeGqlwWpBfM, Part 2 https://youtu.be/Fyxv38B8RrM, and Part 3 https://youtu.be/qR6JWbN3juM.
-- Mark Blackford
8. Aotearoa Astrotourism Academy -- September 10-12
John Hearnshaw and Nalayini Davies announce the launch of a new enterprise, Aotearoa Astrotourism Academy, AAA.
The primary goal of AAA is to offer educational courses for current or aspiring astro-tourism night-sky guides, or for anyone interested in navigating the dark night sky.
We have assembled a small team of dedicated and expert instructors, and the plan is to offer a custom-tailored course over two and a half days (from 3:00 pm Friday afternoon to 4:45 pm Sunday afternoon) on all aspects of night-sky guiding. We hope to impart some of the basic skills and knowledge considered essential for those working in the fast growing astro-tourism industry.
The inaugural course will be in Lake Tekapo village from Friday 10 September 2021 to Sunday 12 September 2021. The venue will be the Godley Hotel, SH8, Lake Tekapo. This will be an intensive course comprising lectures, practical sessions (weather permitting for evening observing) and plenty of interactions between instructors and participants.
The content of the course will be as follows:
• Overview of dark sky places and astro-tourism in New Zealand -- Nalayini Davies
• Astro-tour stargazing (weather permitting) -- Gareth Davies and Alan Gilmore
• Coordinates and time in astronomy -- John Hearnshaw
• Our place in the Universe -- Nalayini Davies
• Principal objects to look at for astro-tourists -- Alan Gilmore
• How binoculars and telescopes work and how to use a telescope -- John Drummond
• Deep field astro-photography -- John Drummond
• Naming of stars and celestial objects -- John Hearnshaw
• Wide field astro-photography and time-lapse videos -- Fraser Gunn
• Notes for astro-tour guides -- Alan Gilmore
• Useful books, publications and apps for night sky guides -- John Hearnshaw and Nalayini Davies
Further details of the Academy and the course offered by AAA are to be found on the website www.aaanz.org. The website should be live from about Easter. We plan to include a guided visit to Mt John Observatory on the Friday afternoon.
Registrations can be made on-line at the website above. The registration fee of $500 covers participation in the course as well as morning and afternoon teas/coffees and lunch on the Saturday and Sunday. It is anticipated that participation will be limited to about 24.
For enquiries please email john.hearnshaw@canterbury.ac.nz or nbrito@vinstar.co.nz
9. Cosmic neutrino from Star-Swallowing Black Hole
Neutrinos are everywhere—trillions of the virtually massless particles pass through your body every second — but they’re notoriously hard to pin down, especially the rare high-energy ones from deep space. Only about a dozen of these cosmic neutrinos are detected annually, and scientists had connected only one to its source. Now, IceCube, the kilometre-wide neutrino detector nestled deep beneath the South Pole, has traced another one back to its far-flung birthplace: a supermassive black hole tearing a star to pieces in a galaxy 750 million light-years away.
“It’s a very exciting story if this is correct,” says Tsvi Piran, a theorist at the Hebrew University of Jerusalem who was not involved in the study. The discovery suggests these rare tidal disruption events (TDEs) could be a major source of high-energy neutrinos and cosmic rays — other deep-space visitors whose origins have been a mystery.
The only way to detect neutrinos is to wait for one to hit something. They don’t often interact with matter, but very rarely they will collide head on with an atomic nucleus, producing a shower of debris particles; as these particles decelerate, they emit a flash of light. To boost the chances of detecting these collisions, researchers need a huge volume of matter. IceCube fishes for them using an array of more than 5000 photon detectors arranged in strings and sunk into 1 cubic kilometre of Antarctic ice. From the arrival time and brightness of the flash at each detector, researchers can calculate the direction a neutrino came from and whether its source is nearby or in deep space.
In 2017, IceCube detected a long-travelled neutrino that, for the first time, was linked to an identifiable source: a super-bright galaxy known as a blazar. Such galaxies contain voracious supermassive black holes in their centres; the matter they suck in burns so hot that it can be seen across the universe. The process also creates a jet of high-velocity matter thought to be pointed straight at Earth.
On 1 October 2019, a flash in the detector revealed another likely deep-space candidate. As they do a few dozen times each year, IceCube researchers sent out an alert so astronomers could scan the sky in the direction of the arriving neutrino. A California telescope, the Zwicky Transient Facility, swung into action and found that it was a TDE, a supermassive black hole tearing apart a nearby star, the team reported in Nature Astronomy on February 22. “When we saw it could be a TDE, we immediately went ‘Wow!’” says lead author Robert Stein of the DESY particle physics laboratory in Germany.
TDEs remain something of a mystery; fewer than 100 have been seen so far. When a star orbits close to a supermassive black hole, the intense gravity distorts its shape — like Earth’s tides on steroids. If it gets too close, the gravity can rip the star up, with half its mass pulled into a hot bright disk around the black hole and the rest flying outward in a long streamer. It’s a similar process to what powers a blazar, but lasts just a few months. By capturing a neutrino from the TDE, the team has now found evidence that TDEs can also feed a short-lived particle jet from the black hole, like a blazar burp.
This particular TDE was not new to astronomers. It had been discovered on 9 April 2019 by the Zwicky survey, and dubbed AT2019dsg. The fact that this one was still powering a neutrino-filled jet 150 days later was a surprise. “We could see the source was really active, with a central engine powering it for a long time,” Stein says.
Astrophysicists don’t understand exactly how accreting black holes power these particle jets. But with two cosmic neutrinos now traced to them, jets are emerging as a primary contender for explaining deep-space neutrinos, edging ahead of neutron stars and stellar explosions. Jets are thought to produce neutrinos in much the same way that particle physicists artificially make neutrinos on Earth: with a high-energy beam of protons (the jet) that slams into surrounding material, explains co-author Suvi Gezari of the Space Telescope Science Institute, who first discovered AT2019dsg. “For TDEs to emerge as a likely site for neutrino production is very exciting,” she says.
This could be an important clue in another mystery for astrophysicists: the source of ultra–high-energy cosmic rays, particles like protons that zip around the cosmos and bombard Earth’s atmosphere daily. Making neutrinos requires accelerating protons to high energy, Piran says, so TDEs could be producing the cosmic rays at the same time.
But Piran says some caution is due. The neutrino and the TDE are linked only by their position in the sky, and IceCube’s fixes are not very precise. Stein concedes there is a one in 500 chance it’s a random coincidence. Such odds won’t impress particle physicists, who usually require a likelihood of one in several million to claim a discovery. “We will have to wait and see if there are additional events,” Stein says. “I wish they had found two neutrinos,” Piran says, “then we would be in business.”
-- See the original article by Daniel Clery at https://www.sciencemag.org/news/2021/02/rare-cosmic-neutrino-traced-star-swallowing-black-hole
10. Antikythera Mechanism Solved?
From the moment it was discovered more than a century ago, scholars have puzzled over the Antikythera mechanism, a remarkable and baffling astronomical calculator that survives from the ancient world.
The hand-powered, 2,000-year-old device displayed the motion of the universe, predicting the movement of the five known planets, the phases of the moon and the solar and lunar eclipses. But quite how it achieved such impressive feats has proved fiendishly hard to untangle.
Now researchers at University College London (UCL) believe they have solved the mystery – at least in part – and have set about reconstructing the device, gearwheels and all, to test whether their proposal works. If they can build a replica with modern machinery, they aim to do the same with techniques from antiquity.
“We believe that our reconstruction fits all the evidence that scientists have gleaned from the extant remains to date,” said Adam Wojcik, a materials scientist at UCL. While other scholars have made reconstructions in the past, the fact that two-thirds of the mechanism are missing has made it hard to know for sure how it worked.
The mechanism, often described as the world’s first analogue computer, was found by sponge divers in 1901 amid a haul of treasures salvaged from a merchant ship that met with disaster off the Greek island of Antikythera. The ship is believed to have foundered in a storm in the first century BC as it passed between Crete and the Peloponnese en route to Rome from Asia Minor.
The battered fragments of corroded brass were barely noticed at first, but decades of scholarly work have revealed the object to be a masterpiece of mechanical engineering. Originally encased in a wooden box one foot tall, the mechanism was covered in inscriptions – a built-in user’s manual – and contained more than 30 bronze gearwheels connected to dials and pointers. Turn the handle and the heavens, as known to the Greeks, swung into motion.
Michael Wright, a former curator of mechanical engineering at the Science Museum in London, pieced together much of how the mechanism operated and built a working replica, but researchers have never had a complete understanding of how the device functioned. Their efforts have not been helped by the remnants surviving in 82 separate fragments, making the task of rebuilding it equivalent to solving a battered 3D puzzle that has most of its pieces missing.
Writing in the journal Scientific Reports, the UCL team describe how they drew on the work of Wright and others, and used inscriptions on the mechanism and a mathematical method described by the ancient Greek philosopher Parmenides, to work out new gear arrangements that would move the planets and other bodies in the correct way. The solution allows nearly all of the mechanism’s gearwheels to fit within a space only 25mm deep.
According to the team, the mechanism may have displayed the movement of the sun, moon and the planets Mercury, Venus, Mars, Jupiter and Saturn on concentric rings. Because the device assumed that the sun and planets revolved around Earth, their paths were far more difficult to reproduce with gearwheels than if the sun was placed at the centre. Another change the scientists propose is a double-ended pointer they call a “Dragon Hand” that indicates when eclipses are due to happen.
The researchers believe the work brings them closer to a true understanding of how the Antikythera device displayed the heavens, but it is not clear whether the design is correct or could have been built with ancient manufacturing techniques. The concentric rings that make up the display would need to rotate on a set of nested, hollow axles, but without a lathe to shape the metal, it is unclear how the ancient Greeks would have manufactured such components.
“The concentric tubes at the core of the planetarium are where my faith in Greek tech falters, and where the model might also falter,” said Wojcik. “Lathes would be the way today, but we can’t assume they had those for metal.”
Whether or not the model works, more mysteries remain. It is unclear whether the Antikythera mechanism was a toy, a teaching tool or had some other purpose. And if the ancient Greeks were capable of such mechanical devices, what else did they do with the knowledge?
“Although metal is precious, and so would have been recycled, it is odd that nothing remotely similar has been found or dug up,” Wojcik said. “If they had the tech to make the Antikythera mechanism, why did they not extend this tech to devising other machines, such as clocks?”
-- See Guardian science editor Ian Sample's original article, with images, at https://www.theguardian.com/science/2021/mar/12/scientists-move-closer-to-solving-mystery-of-antikythera-mechanism
11. 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 2021 year starts at $40 for an ordinary
member, which includes an electronic subscription to our journal
'Southern Stars'.
12. 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
13. Quotes
"Potatoes make French fries, chips and vodka. It's like the other vegetables aren't even trying." -- Shared from: http://www.ebaumsworld.com/.../fridays-funny.../86095842/...
"Money isn't everything -- but it sure keeps the kids in touch." --
Twitter
"Do not regret growing older. It is a privilege denied to many."
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
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December Celestial Calendar by Dave Mitsky
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Minor Planet Occultation Updates:
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Further links and discussion can be found at the groups/links below
Astronomy in New Zealand - Groups.io
https://groups.io/g/AstronomyNZ
Astronomy in New Zealand - Facebook
https://www.facebook.com/groups/5889909863/
Google Group
https://groups.google.com/g/nzastrochat
Astronomy in Wellington
https://www.facebook.com/groups/11451597655/
Blogger Posts
http://laintal.blogspot.com/
Twitter
https://twitter.com/Laintal
Reddit
https://www.reddit.com/user/Edwin_Rod_NZ
Quaroa
https://www.quora.com/q/astronomyinnewzealand
Groups.io
Astronomy in New Zealand
https://groups.io/g/AstronomyNZ
AstronomyNZ@groups.io
Wellington Astronomers
https://groups.io/g/WellingtonAstronomers
WellingtonAstronomers@groups.io
AucklandAstronomers
https://groups.io/g/AucklandAstronomers
AucklandAstronomers@groups.io
North Island Astronomers
https://groups.io/g/NorthIslandAstronomers
NorthIslandAstronomers@groups.io
South Island Astronomers
https://groups.io/g/SouthIslandAstronomers
SouthIslandAstronomers@groups.io
NZAstrochat
https://groups.io/g/NZAstrochat
NZAstrochat@groups.io
NZ Photographers And Observers
https://groups.io/g/NZPhotographers
NZPhotographers@groups.io
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Please note:
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The above post/email/update represents my own words, views, research and opinions, unless stated otherwise the above work
represents my own writing. I’ll give credit or thanks if I have used or represented other people’s words and/or opinions.
The links and references listed below represent the work and research of the respective author’s.
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