RASNZ_20_10_2019
Royal Astronomical Society of New Zealand
eNewsletter: No. 226, Date 20 October 2019
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. Astronomers Awarded Nobel Prize in Physics
2. Kyra Xavia Honoured by the IDA
3. New RASNZ Executive Secretary
4. The Solar System in November
5. RASNZ Beatrice Hill-Tinsley Lecture Series
6. Andromeda Stardate November 1-3
7. Burbidge Dinner - November 22
8. NZ Astrophotography Weekend - December 7-9
9. Variable Star News
10. Star Parties in 2020
11. 2020 Conference and RASNZ Centenary
12. RASNZ 100 Programme
13. Brashear Lens History
14. Comet Borisov's Size
15. Fast Radio Burst Plumbs Galaxy's Halo
16. Marsquakes on Line
17. Kingdon-Tomlinson Fund
1. Astronomers Awarded Nobel Prize in Physics
The 2019 Nobel Prize for physics prize was split two ways, but both halves went for discoveries beyond Earth. One was for a finding that is, by astronomical standards, quite close by — a planet going around a star a mere 50 light-years distant. The other was for an overview of the entire universe.
In October 1995 Michel Mayor and Didier Queloz, a pair of astronomers then working at the University of Geneva, presented a paper at a scientific conference in Florence. A few months earlier, they had discovered a planet beyond the solar system. It was a gaseous ball twice the size of Jupiter and was going around a star called 51 Pegasi, at a distance of about 8m kilometres — a twentieth of the distance from Earth to the sun. As a consequence of this proximity it orbited 51 Pegasi once every four terrestrial days and had a surface temperature in excess of 1,000°C. The discovery was a puzzle for astronomers. Until then they had thought that such large, Jupiter-like planets could form only far away from their host stars.
That discovery of 51 Pegasi b, as this planet is now known, launched the field of exoplanet astronomy. To date, astronomers have found almost 4,000 other such planets — and the wide variety of sizes, orbits and compositions of these objects continues to surprise researchers, who have yet to come up with a comprehensive physical theory of how planetary systems form.
Since planets do not shine by themselves, astronomers needed to develop special methods to find them. The one Dr Mayor and Dr Queloz used relies on a phenomenon called the Doppler effect. As a planet orbits its star, the star will also move slightly as it orbits around the centre of mass of the two. This will cause the frequency of the starlight arriving at Earth to oscillate (that is, the star will change colour slightly) in the same way that the frequency of an ambulance siren shifts as the vehicle passes by. Nowadays a second approach, which measures the dip in starlight as a planet passes across its disc, is more common. But the Doppler-shift method, as employed by Dr Mayor and Dr Queloz, is still used as well.
The half-prize for the overview of the universe went to James Peebles of Princeton University, who has spent decades developing a theoretical framework to describe how the cosmos evolved from the Big Bang 13.7bn years ago to the state it finds itself in today. According to Sweden’s Royal Academy of Science, which awards the physics prize, Dr Peebles was the person who, in the 1960s, shifted cosmology from speculation to a rigorous discipline.
Until the first decades of the 20th century, astronomers had assumed the universe to be stationary and eternal. This was shown to be incorrect in the 1920s, with the discovery that all galaxies are moving away from each other. In other words, the universe is expanding. Rewind the clock and this means that, at the start of time, now called the Big Bang, the universe would have been incredibly small, hot and dense.
Around 400,000 years after the Big Bang it had expanded and cooled enough for light to travel through space unimpeded. Astronomers can detect the glow of that first light today but, because its wavelength has been stretched by 13bn years of the expansion of space, it manifests itself not as light but as a glow of microwave radiation that fills the entire sky. This cosmic microwave background was discovered, by accident, in 1964 by radio astronomers, who used earlier theoretical work by Dr Peebles to explain their discovery. Dr Peebles also showed that tiny fluctuations in the temperature of the microwave background were crucial to understanding how matter would later clump together to form galaxies and galaxy clusters.
Since the early 1990s, space-based observatories have built up increasingly precise portraits of the cosmic microwave background and, true to Dr Peebles’s predictions, these show that temperature variations of just one hundred-thousandth of a degree map onto the observed distribution of matter and energy in the universe.
Rewarding cosmic shifts in understanding might seem to be a normal day’s work for those who give out the Nobel prizes. But Martin Rees, Britain’s Astronomer Royal, sees something new in this year’s awards in physics. The award to Dr Peebles, he says, will be welcomed by physicists as recognition of a lifetime of sustained contributions and insights by an acknowledged intellectual leader, rather than a one-off achievement.
Such lifetime-achievement awards are more usually associated with the Oscars than the Nobels. But that is not inappropriate. In many ways the Nobel prizes are a Swedish version of the Oscars — with seriousness substituted for superfice, substance for style, and genuine modesty among the winners for the false sort.
-- From 'The Economist' October 12, p.78. The original article is at
https://www.economist.com/science-and-technology/2019/10/12/batteries-exoplanets-cosmology-and-cell-biology-win-nobel-laurels
2. Kyra Xavia Honoured by the IDA
Each year, the International Dark-Sky Association recognizes and celebrates the incredible achievements of individuals and groups who are committed to our mission to preserve and protect the night. As leaders in their communities, the awardees play a key role in strengthening the global dark sky movement and empowering others to join the fight against light pollution.
“IDA is proud to honor such an inspiring, energetic, and effective group of dark sky advocates. We are grateful that they are a part of the global dark sky network, working on the ground to combat light pollution in their communities and beyond”, says IDA Board President, Ken Kattner.
Among the recipients is Kyra Xavia (New Zealand). Kyra Xavia is an IDA Delegate and co-leader of the Dunedin Dark Skies Group, who works on light abatement education. Her outstanding public education through multimedia outlets, public forums, council-led forums, school visits and meetings, has enlightened the Dunedin community of the imminent dangers and challenges of an increasingly over-lit world. Her work has resulted in the whole city of Dunedin opting in 2019 to replace all its street lights with 3000K LEDs.
For the full list see
https://www.darksky.org/ida-announces-2019-award-winners/
3. New RASNZ Executive Secretary
John Drummond of Gisborne was appointed by the RASNZ Council as the new RASNZ Executive Secretary on the 12th October 2019. Any correspondence with the secretary can be achieved by the following -
* Email: rasnz.secretary@gmail.com
* Phone: 0275 609 287 (cell), (06) 8627 557 (home)
* Postal: PO Box 3181, Wellington, 6140 or
John Drummond, PO Box 113, Patutahi 4045.
4. The Solar System in November
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.
THE SUN and PLANETS in November, Rise & Set, Magnitude & Constellation
November 1 NZDT November 30 NZDT
Mag Cons Rise Set Mag Cons Rise Set
SUN -26.7 Lib 6.06am 8.03pm -26.7 Oph 5.40am 8.38pm
Merc 0.6 Lib 6.50am 9.48pm -0.6 Lib 4.49am 6.52pm
Venus -3.8 Lib 7.06am 9.49pm -3.9 Sgr 7.25am 10.50pm
Mars 1.8 Vir 5.19am 6.15pm 1.7 Vir 4.11am 5.58pm
Jup -1.9 Oph 8.38am 11.44pm -1.8 Sgr 7.09am 10.17pm
Sat 0.6 Sgr 10.17am 1.16am 0.6 Sgr 8.34am 11.32pm
Uran 5.7 Ari 7.28pm 6.08am 5.7 Ari 5.29pm 4.11am
Nep 7.8 Aqr 3.22pm 4.17am 7.9 Aqr 1.27pm 2.22am
Pluto 14.5 Sgr 10.40am 1.40am 14.5 Sgr 8.49am 11.48pm
November 1 NZDT November 30 NZDT
Twilights morning evening morning evening
Civil: start 5.39am, end 8.31pm start 5.10am, end 9.09pm
Nautical: start 5.03am, end 9.07pm start 4.29am, end 9.50pm
Astro: start 4.24am, end 9.46pm start 3.41am, end10.38pm
November PHASES OF THE MOON, times NZDT & UT
First quarter: Nov 4 at 11.23pm (10:23 UT).
Full Moon: Nov 13 at 2.34am (Nov 12, 13:34 UT)
Last quarter Nov 20 at 10.11am (Nov 19, 21:11 UT)
New Moon: Nov 27 at 4.06am (Nov 26, 15:06 UT)
PLANETS in NOVEMBER
MERCURY is too close to the Sun to observe for much of November. On the evening of the 1st at about 9pm, it will 7° above the horizon and 3° to the left of Venus, so giving a guide to Mercury. Earlier on the 1st, Mercury is stationary. It is stationary again on the 21st. Between the two dates the planet moves to the west and is at inferior conjunction on the 12th. A solar transit at this conjunction is unobservable from NZ and Australia.
VENUS starts November level with Mercury, but Venus will be moving to the east so the two separate in a few days. It remains an evening object and sets well over 2 hours after the Sun at the end of November. On the evening of the 24th, Venus will be 1.5° from Jupiter. An hour after sunset they will be some 10° above the horizon. Four evenings later, with Venus 4° above Jupiter, the two will be joined by the crescent moon, a couple of degrees below Jupiter.
MARS moves a little further up into the morning sky, rising 90 minutes before the Sun by the 30th. Early in the month Mars moves past Spica, with the two less than 3° apart on the morning of the 11th. Mars then rises only an hour before the Sun, so will be very low
JUPITER is an early evening object so will be low as the sky darkens. After the 24th when Jupiter and Venus are close, Jupiter will become the lower of the two.
SATURN is an evening object setting just before midnight by the end of November. This month's lunar occultation on the 2nd is visible from New Zealand. The disappearance behind the moon Earth-lit limb is observable but occurs during evening twilight for the South Island. The reappearance is about hour later but takes place at the sunlit limb.
PLUTO, like Saturn, is in Sagittarius, the two planets are less than 4° apart at the end of the month.
URANUS is an evening object. The almost full moon is 4° from the planet on the 11th.
NEPTUNE, is in Aquarius setting well after midnight. Its apparent motion is to the west until it is stationary on the 28th. Its motion then reverses to the normal east.
POSSIBLE BINOCULAR ASTEROIDS in NOVEMBER
November 1 NZDT November 30 NZDT
Mag Cons transit Mag Cons transit
(1) Ceres 9.2 Oph 4.16pm 9.2 Sgr 3.11pm
(4) Vesta 6.7 Tau 2.09am 6.8 Cet 11.46pm
(9) Metis 8.7 Psc 12.41am 9.4 Psc 10.26pm
(29) Amphitrite 9.2 Psc 11.29pm 9.8 Psc 9.26pm
CERES gets low in the evening sky. Venus passes the asteroid on the 30th, with Ceres 2° to the upper left of Venus at 10 pm.
VESTA is at its brightest being at opposition on November 12. It moves from Taurus to Cetus on the 12th.
METIS and AMPHITRITE are evening objects moving to the west through Pisces. Amphitrite is stationary on the 27th.
-- Brian Loader
5. RASNZ Beatrice Hill-Tinsley Lecture Series
The remaining lectures by Babak A. Tafreshi in the 2019 Beatrice Hill Tinsley Lecture series, funded by the RASNZ Lecture Trust Inc, are at:
Dunedin (Dunedin Astronomical Society): October 28, time 4 p.m.
Venue: Otago Museum, Hutton Theatre
Admission charge: No charge, but donations to defray costs accepted.
Wanganui (Wanganui Astronomical Society): October 30, time 7.30pm
Venue: Concert Chamber, Whanganui War Memorial Hall, Watt Street.
Admission charge: $5pp, Family $10
New Plymouth (New Plymouth Astronomical Society): October 31, time 7:30pm
Venue: Spotswood College Staffroom
Admission charge: Adults $10, Children Free
Event details and bookings: Cash Door Sales Only - No EFTPOS
For more information, see - https://www.rasnz.org.nz/rasnz/beatrice-hill-tinsley-lectures.
6. Andromeda Stardate November 1-3
The Andromeda Stardate is an astronomical festival to be held at Stonehenge Aotearoa in the Wairarapa. The program includes lectures, workshops, barbecues, movies, live music and observing sessions. It begins on Friday afternoon November 1st and runs through to Sunday 3rd. Overnight camping and caravan sites are available.
Registration Fee: (all or part of Andromeda Stardate 2019)
Adults: $30; young persons (5 to 15 years) $5; children (under 5): free. Camping Fee for weekend $10 per tent or caravan per night.
To book your place or for further information phone (06) 377 1600,
or visit our web page: www.stonehenge-aotearoa.co.nz
-- Kay Leather, Treasurer, Phoenix Astronomical Society
7. Burbidge Dinner - November 22
The Auckland Astronomical Society's Burbidge Dinner 2019 is on
Friday 22 November 2019.
Start Time: 7:00pm (doors open at 6:30pm)
Venue: Ellerslie Events Centre, Pakuranga Hunt Room.
After Dinner Lecture by Professor Joss Bland-Hawthorn, (Director, Sydney Institute of Astronomy, University of Sydney) "The Galactic Centre - a Window into the Future". See the lecture abstract at
https://www.astronomy.org.nz/new/public/eventcalendar.aspx
As well as our guest speaker there will be the prize-giving for the New Zealand Astrophotography Competition including the Harry Williams Trophy for the supreme winner, and the Beaumont Writing Prize. A spectacular venue, great meal, cash bar and ample free parking.
Tickets: $65 pp, earlybird price of $60.00 is available until 31st October includes a buffet dinner.
Tickets can be booked: - by email at events@astronomy.org.nz -by phone to Niven on 021 935 261 or Bill on 021 225 8175
-- From the Auckland Astronomical Society's website.
8. NZ Astrophotography Weekend - December 7-9
At the Foxton Beach Bible Camp, Foxton Beach, Horowhenua.
The Horowhenua Astronomical Society is hosting the sixth New Zealand Astrophotography Weekend. Held in the lower North Island it is an annual event dedicated to astrophotography in a wonderful dark-sky location. It is open to everyone interested in astrophotography - from beginners to advanced. Come along and share your knowledge, tips and experiences
All sorts of astrophotography can be undertaken - solar-system/nightscapes/deep-sky.
The weekend shall consist of: practical astrophotography, image processing, presentations, bring-and-buy, fish and chips dinner, late-night movies. Everyone is encouraged to bring along their own telescopes, binoculars, mounts, cameras, etc. however basic they might be.
See www.nzapw.org.nz for costs and registration details.
Please book early so we know the numbers.
-- Steve Lang
9. Variable Star News
Eclipse of BL Tel
Algol variables are eclipsing binary stars that are detached; the period of eclipse is determined by the orbital period of the star. Eclipse characteristics are usually a period of a few days or less and a small magnitude change of a magnitude or two. The Algol type variable BL Tel is special because it has a long period a bit over two years (estimate 778 days) and also a large decrease in brightness of mag 2.5 (from about mag 7.0 to about mag 9.5) making it a relatively easy star to monitor. The duration of the eclipse is about two months.
BL Tel will be undergoing eclipse about the time this Newsletter is distributed. BL Tel has been the subject of a long running campaign to observe these eclipses; 8 eclipses were observed in the interval from 1983 and 2000. The monitoring has continued under VSS (for information refer https://www.variablestarssouth.org/project-bl-tel-eclipse/). The star will move into the southwestern twilight about mid-eclipse meaning the later part of the event will not be observable
BL Tel is also special as one of the stars is an intrinsic variable; recently Dave Blane has been making observations of these small (range about 0.2 mags) out of eclipse variations.
Short Period Pulsator Section
The AAVSO is setting up a new section to coordinate work on “short term pulsators” defined as stars that have light pulsations from internal changes within the star and short periods of a few hours to ten days or so. Short period pulsators (SPP) include a number of different variable star types, including Cepheids, RR Lyrae stars, and delta Scuti stars For many of these variable stars the light curve is regular from cycle to cycle but for others the light curve varies in height and shape from cycle to cycle ? called the Blazhko effect after the Russian astronomer who first drew attention to it. Multiple pulsation periods which alternately interfere or reinforce each other can result in very complex light curves; multi-periodic stars like these must be observed frequently over weeks or months to provide enough data to determine the periods involved.
For information on the SPP group go to https://www.aavso.org/aavso-short-period-pulsator-section. Visit AAVSO SPP Program page if you are interested in choosing observing targets.
AAVSO Looking to the Future
The AAVSO has been undertaking a consultation amongst its members on the future shape of the organisation (see their “Planning AAVSO’s future” forum.). AAVSO Director Stella Kafka and President Gordon Myers reached out to Variable Stars South (VSS) and arranged a teleconference on Saturday 12th October in which Mark Blackford and two other VSS members took part. Several topics were raised including what tasks are most usefully done by amateurs now and in the near future given the likely dramatic impact of all-sky surveys and robotic telescope installations. For sure more will come out of the on-going dialogue as discussion continues. The next step will be the AAVSO Annual Conference being held 18-21 October at Las Cruces New Mexico.
-- Alan Baldwin
10. Star Parties in 2020
The following star parties are planned for 2020:
Central Star Party: Thursday 16th to Sunday 19th of January at the Tuki Tuki Camp site in the Hawkes Bay. https://censtar.party/
Stardate North Island: Friday 21st to Sunday 23rd February at Stonehenge, Carterton. Check Phoenix website - http://www.astronomynz.org/
Stardate South Island: Late February. At Staveley, South Island. Keep an eye on https://cas.org.nz/
Stargazers Getaway 2020 Camp Iona, September 18th, 19th and 20th 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 10 – Monday 13 April. For more details see http://nacaa.org.au/2020/about
-- Mostly from 'Keeping in Touch' #34, 27th Sept 2019.
11. 2020 Conference and RASNZ Centenary
The 2020 Conference will be held Friday 8 - Sunday 10 May 2020 in Wellington. The Wellington Astronomical Society is hosting the Conference.
The Conference venue is the Wharewaka Function Centre located on the waterfront just 2 minutes walk from Te Papa.
As the programme will commence at the earlier than usual time of 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 conclude mid-afternoon on Sunday.
Planning for this event is progressing and further details will be announced in the near future once they are confirmed. In the meantime please mark the above dates in your calendar and consider participating in this Conference as RASNZ celebrates its centenary.
-- Glen Rowe, Chair, Standing Conference Committee.
12. RASNZ 100 Programme
The RASNZ Council is pleased to announce its RASNZ 100 Programme to support Affiliated Societies celebrating the RASNZ's Centennial year in 2020. The programme encourages Affiliated Societies to promote astronomy within their regions to raise the profile of the Society, the RASNZ and astronomy in general. The RASNZ is providing up to $500 to each Affiliated Society to support RASNZ 100 events run by Affiliated Societies. For more information, see https://www.rasnz.org.nz/groups-news-events/rasnz-100-events
-- From 'Keeping in Touch' #34. 27th Sept 2019
13. Brashear Lens History
A history of the lens in the Brashear telescope now reassembled at Lake Tekapo's Dark Sky Project is detailed in "A tale of three telescopes: the John A. Brashear Company and its 46-cm objective" by Richard Taibi.
The paper is in the Journal of Astronomical History and Heritage, Volume 22, No.2, p.247, and can be viewed at
http://www.narit.or.th/en/files/2019JAHHvol22/2019JAHH...22..247T.pdf
The Newsletter editor can pass along a pdf if the above link doesn't work.
14. Comet Borisov's Size
A paper by David Jewitt and Jane Luu provides an estimate of the size of Comet Borisov's nucleus. The paper's abstract follows.
We present initial observations of the interstellar body 2I/Borisov taken to determine its nature prior to the perihelion in 2019 December. Images from the Nordic Optical Telescope show a prominent, morphologically stable dust coma and tail. The dust cross-section within 15,000 km of the nucleus averages 130 sq. km (assuming geometric albedo 0.1) and increases by about 1 percent per day. If sustained, this rate indicates that the comet has been active for 100 days prior to the observations. Cometary activity thus started in 2019 June, at which time C/Borisov was at 4.5 AU from the Sun, a typical distance for the onset of water ice sublimation in comets. The dust optical colors, B-V = 0.800.05, V-R = 0.470.03 and R-I = 0.490.05 are identical to those of a sample of (solar system) long-period comets. The colors are similar to those of 1I/(2017 U1) 'Oumuamua, indicating a lack of the ultrared matter that is common in the Kuiper belt, on both interstellar objects. The effective size of the dust particles is estimated as 100 microns, based on the length of the dust tail and the 100 day lifetime. With this size, the ejected dust mass is of order 1.3e7 kg [13,000 tonnes] and the current dust mass loss rate 2 kg/s. We set an upper limit to the nucleus radius using photometry of <3 .8="" 0.1="" a="" again="" albedo="" argument="" be="" br="" few="" for="" however="" hundred="" in="" km="" likely="" meters="" much="" must="" nucleus="" radius.="" show="" smaller="" statistical="" that="" the="" to="" use="" we="">
The paper "Initial Characterization of Interstellar Comet 2I/2019 Q4 (Borisov)" by David Jewitt and Jane Luu is at https://arxiv.org/abs/1910.02547
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The small size of the nucleus raises the possibility that it will disintegrate during its perihelion. If so then the comet could be briefly bright.
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Syuichi Nakano, Sumoto, Japan, has computed the asymptotic
points of 2I/Borisov. The original asymptotic point from whence the comet came on its way to the solar system is located at R.A. = 2h11m.2m, Decl. = +59d26' (equinox J2000.0), which is in the constellation Cassiopeia. The comet is headed toward the future asymptotic point at R.A. = 18h21m.5, Decl. = -51d59' (which is in Telescopium).
-- From Central Bureau Electronic Telegram No. 4679, 2019 October 18
15. Fast Radio Burst Plumbs Galaxy's Halo
In November 2018 the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope pinpointed a fast radio burst, named FRB 181112. Follow-up observations with European Southern Observatory's Very Large Telescope (VLT) and other telescopes revealed that the radio pulses passed through the halo of a massive galaxy on their way toward Earth. This finding allowed astronomers to analyse the radio signal for clues about the nature of the halo gas.
Astronomers still don't know what causes fast radio bursts and only recently have been able to trace some of these very short, very bright radio signals back to the galaxies in which they originated. "When we overlaid the radio and optical images, we could see straight away that the fast radio burst pierced the halo of this coincident foreground galaxy and, for the first time, we had a direct way of investigating the otherwise invisible matter surrounding this galaxy," said coauthor Cherie Day, a PhD student at Swinburne University of Technology, Australia.
A galactic halo contains both dark and ordinary-or baryonic-matter that is primarily in the form of a hot ionised gas. While the luminous part of a massive galaxy might be around 30 000 light years across, its roughly spherical halo is ten times larger in diameter. Halo gas fuels star formation as it falls towards the centre of the galaxy, while other processes, such as supernova explosions, can eject material out of the star-forming regions and into the galactic halo. One reason astronomers want to study the halo gas is to better understand these ejection processes which can shut down star formation.
J. Xavier Prochaska, professor of astronomy and astrophysics at the University of California Santa Cruz and lead author of the study noted that "This galaxy's halo is surprisingly tranquil. The radio signal was largely unperturbed by the galaxy, which is in stark contrast to what previous models predict would have happened to the burst."
The signal of FRB 181112 was a few pulses, each lasting less than 40 microseconds (10 000 times shorter than the blink of an eye). The short duration of the pulses puts an upper limit on the density of the halo gas because passage through a denser medium would broaden the duration of the radio signal. The researchers calculated that the density of the halo gas must be less than 0.1 atoms per cubic centimetre (equivalent to several hundred atoms in a volume the size of a child's balloon). [A cc of air at sea level contains 2.7x10e19 molecules.]
The study found no evidence of cold turbulent clouds or small dense clumps of cool halo gas. The fast radio burst signal also yielded information about the magnetic field in the halo, which is very weak - a billion times weaker than that of a refrigerator magnet.
At this point, with results from only one galactic halo, the researchers cannot say whether the low density and low magnetic field strength they measured are unusual or if previous studies of galactic halos have overestimated these properties. Prochaska said he expects that ASKAP and other radio telescopes will use fast radio bursts to study many more galactic halos and resolve their properties.
-- Abridged from the ESO press release at https://www.eso.org/public/news/eso1915/ passed along by Karen pollard.
16. Marsquakes on Line
Put an ear to the ground on Mars and you’ll be rewarded with a symphony of sounds. Granted, you’ll need superhuman hearing, but NASA’s InSight lander comes equipped with a very special “ear.” The Insight spacecraft’s exquisitely sensitive seismometer, called the Seismic Experiment for Interior Structure (SEIS), can pick up vibrations as subtle as a breeze. The instrument was provided by the French space agency, Centre National d’Études Spatiales (CNES), and its partners.
SEIS was designed to listen for marsquakes. Scientists want to study how the seismic waves of these quakes move through the planet’s interior, revealing the deep inner structure of Mars for the first time. But after the seismometer was set down by InSight’s robotic arm, Mars seemed shy. It didn’t produce its first rumbling until this past April, and this first quake turned out to be an odd duck. It had a surprisingly high-frequency seismic signal compared to what the science team has heard since then. Out of more than 100 events detected to date, about 21 are strongly considered to be quakes. The remainder could be quakes as well, but the science team hasn’t ruled out other causes.
Put on headphones to listen to two of the more representative quakes SEIS has detected. These occurred on May 22 (the 173rd Martian day, or sol, of the mission) and July 25 (Sol 235). Far below the human range of hearing, these sonifications from SEIS had to be speeded up and slightly processed to be audible through headphones. Both were recorded by the “very broad band sensors” on SEIS, which are more sensitive at lower frequencies than its short period sensors. The Sol 173 quake is about a magnitude 3.7; the Sol 235 quake is about a magnitude 3.3:
* https://soundcloud.com/nasa/quake-sol-173
* https://soundcloud.com/nasa/quake-sol-235
Each quake is a subtle rumble. The Sol 235 quake becomes particularly bass-heavy toward the end of the event. Both suggest that the Martian crust is like a mix of the Earth’s crust and the Moon’s. Cracks in Earth’s crust seal over time as water fills them with new minerals. This enables sound waves to continue uninterrupted as they pass through old fractures. Drier crusts like the Moon’s remain fractured after impacts, scattering sound waves for tens of minutes rather than allowing them to travel in a straight line. Mars, with its cratered surface, is slightly more Moon-like, with seismic waves ringing for a minute or so, whereas quakes on Earth can come and go in seconds.
SEIS has no trouble identifying quiet quakes, but its sensitive ear means scientists have lots of other noises to filter out. Over time, the team has learned to recognize the different sounds. And while some are trickier than others to spot, they all have made InSight’s presence on Mars feel more real to those working with the spacecraft.
“It’s been exciting, especially in the beginning, hearing the first vibrations from the lander,” said Constantinos Charalambous, an InSight science team member at Imperial College London who works with the SP sensors. “You’re imagining what’s really happening on Mars as InSight sits on the open landscape.”
Charalambous and Nobuaki Fuji of Institut de Physique du Globe de Paris provided the audio samples for this story, including the one below, which is also best heard with headphones and captures the array of sounds they’re hearing: https://youtu.be/m9cCuW9nIQg
Wind gusts can also create noise. The team is always on the hunt for quakes, but they’ve found the twilight hours are one of the best times to do so. During the day, sunlight warms the air and creates more wind interference than at night.
Evening is also when peculiar sounds that the InSight team has nicknamed “dinks and donks” become more prevalent. The team knows they’re coming from delicate parts within the seismometer expanding and contracting against one another and thinks heat loss may be the factor, similar to how a car engine “ticks” after it’s turned off and begins cooling.
You can hear a number of these dinks and donks in this next set of sounds, recorded just after sundown on July 16 (Sol 226). Listen carefully and you can also pick out an eerie whistling that the team thinks may be caused by interference in the seismometer’s electronics:
* https://soundcloud.com/nasa/dinks-and-donks-sample
See the original text & graphics at:
https://www.jpl.nasa.gov/news/news.php?release=2019-195
-- From the Jet Propulsion Laboratory press release forwarded by Karen Pollard. 17. Kingdon-Tomlinson Fund
The RASNZ is responsible for recommending to the trustees of the Kingdon
Tomlinson Fund that grants be made for astronomical projects. The grants may be to any person or persons, or organisations, requiring funding for any projects or ventures that promote the progress of astronomy in New Zealand. The deadline for this round of the Kingdon-Tomlinson Grants is Friday 1st November 2019. Full details are set down in the RASNZ By-Laws, Section J. Information on the K-T Fund is at
http://rasnz.org.nz/rasnz/kt-fund
Send applications to the RASNZ Executive Secretary at rasnz.secretary@gmail.com.
The application form at
http://rasnz.org.nz/Downloadable/RASNZ/KT_Application2019.pdf
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
eNewsletter: No. 226, Date 20 October 2019
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. Astronomers Awarded Nobel Prize in Physics
2. Kyra Xavia Honoured by the IDA
3. New RASNZ Executive Secretary
4. The Solar System in November
5. RASNZ Beatrice Hill-Tinsley Lecture Series
6. Andromeda Stardate November 1-3
7. Burbidge Dinner - November 22
8. NZ Astrophotography Weekend - December 7-9
9. Variable Star News
10. Star Parties in 2020
11. 2020 Conference and RASNZ Centenary
12. RASNZ 100 Programme
13. Brashear Lens History
14. Comet Borisov's Size
15. Fast Radio Burst Plumbs Galaxy's Halo
16. Marsquakes on Line
17. Kingdon-Tomlinson Fund
1. Astronomers Awarded Nobel Prize in Physics
The 2019 Nobel Prize for physics prize was split two ways, but both halves went for discoveries beyond Earth. One was for a finding that is, by astronomical standards, quite close by — a planet going around a star a mere 50 light-years distant. The other was for an overview of the entire universe.
In October 1995 Michel Mayor and Didier Queloz, a pair of astronomers then working at the University of Geneva, presented a paper at a scientific conference in Florence. A few months earlier, they had discovered a planet beyond the solar system. It was a gaseous ball twice the size of Jupiter and was going around a star called 51 Pegasi, at a distance of about 8m kilometres — a twentieth of the distance from Earth to the sun. As a consequence of this proximity it orbited 51 Pegasi once every four terrestrial days and had a surface temperature in excess of 1,000°C. The discovery was a puzzle for astronomers. Until then they had thought that such large, Jupiter-like planets could form only far away from their host stars.
That discovery of 51 Pegasi b, as this planet is now known, launched the field of exoplanet astronomy. To date, astronomers have found almost 4,000 other such planets — and the wide variety of sizes, orbits and compositions of these objects continues to surprise researchers, who have yet to come up with a comprehensive physical theory of how planetary systems form.
Since planets do not shine by themselves, astronomers needed to develop special methods to find them. The one Dr Mayor and Dr Queloz used relies on a phenomenon called the Doppler effect. As a planet orbits its star, the star will also move slightly as it orbits around the centre of mass of the two. This will cause the frequency of the starlight arriving at Earth to oscillate (that is, the star will change colour slightly) in the same way that the frequency of an ambulance siren shifts as the vehicle passes by. Nowadays a second approach, which measures the dip in starlight as a planet passes across its disc, is more common. But the Doppler-shift method, as employed by Dr Mayor and Dr Queloz, is still used as well.
The half-prize for the overview of the universe went to James Peebles of Princeton University, who has spent decades developing a theoretical framework to describe how the cosmos evolved from the Big Bang 13.7bn years ago to the state it finds itself in today. According to Sweden’s Royal Academy of Science, which awards the physics prize, Dr Peebles was the person who, in the 1960s, shifted cosmology from speculation to a rigorous discipline.
Until the first decades of the 20th century, astronomers had assumed the universe to be stationary and eternal. This was shown to be incorrect in the 1920s, with the discovery that all galaxies are moving away from each other. In other words, the universe is expanding. Rewind the clock and this means that, at the start of time, now called the Big Bang, the universe would have been incredibly small, hot and dense.
Around 400,000 years after the Big Bang it had expanded and cooled enough for light to travel through space unimpeded. Astronomers can detect the glow of that first light today but, because its wavelength has been stretched by 13bn years of the expansion of space, it manifests itself not as light but as a glow of microwave radiation that fills the entire sky. This cosmic microwave background was discovered, by accident, in 1964 by radio astronomers, who used earlier theoretical work by Dr Peebles to explain their discovery. Dr Peebles also showed that tiny fluctuations in the temperature of the microwave background were crucial to understanding how matter would later clump together to form galaxies and galaxy clusters.
Since the early 1990s, space-based observatories have built up increasingly precise portraits of the cosmic microwave background and, true to Dr Peebles’s predictions, these show that temperature variations of just one hundred-thousandth of a degree map onto the observed distribution of matter and energy in the universe.
Rewarding cosmic shifts in understanding might seem to be a normal day’s work for those who give out the Nobel prizes. But Martin Rees, Britain’s Astronomer Royal, sees something new in this year’s awards in physics. The award to Dr Peebles, he says, will be welcomed by physicists as recognition of a lifetime of sustained contributions and insights by an acknowledged intellectual leader, rather than a one-off achievement.
Such lifetime-achievement awards are more usually associated with the Oscars than the Nobels. But that is not inappropriate. In many ways the Nobel prizes are a Swedish version of the Oscars — with seriousness substituted for superfice, substance for style, and genuine modesty among the winners for the false sort.
-- From 'The Economist' October 12, p.78. The original article is at
https://www.economist.com/science-and-technology/2019/10/12/batteries-exoplanets-cosmology-and-cell-biology-win-nobel-laurels
2. Kyra Xavia Honoured by the IDA
Each year, the International Dark-Sky Association recognizes and celebrates the incredible achievements of individuals and groups who are committed to our mission to preserve and protect the night. As leaders in their communities, the awardees play a key role in strengthening the global dark sky movement and empowering others to join the fight against light pollution.
“IDA is proud to honor such an inspiring, energetic, and effective group of dark sky advocates. We are grateful that they are a part of the global dark sky network, working on the ground to combat light pollution in their communities and beyond”, says IDA Board President, Ken Kattner.
Among the recipients is Kyra Xavia (New Zealand). Kyra Xavia is an IDA Delegate and co-leader of the Dunedin Dark Skies Group, who works on light abatement education. Her outstanding public education through multimedia outlets, public forums, council-led forums, school visits and meetings, has enlightened the Dunedin community of the imminent dangers and challenges of an increasingly over-lit world. Her work has resulted in the whole city of Dunedin opting in 2019 to replace all its street lights with 3000K LEDs.
For the full list see
https://www.darksky.org/ida-announces-2019-award-winners/
3. New RASNZ Executive Secretary
John Drummond of Gisborne was appointed by the RASNZ Council as the new RASNZ Executive Secretary on the 12th October 2019. Any correspondence with the secretary can be achieved by the following -
* Email: rasnz.secretary@gmail.com
* Phone: 0275 609 287 (cell), (06) 8627 557 (home)
* Postal: PO Box 3181, Wellington, 6140 or
John Drummond, PO Box 113, Patutahi 4045.
4. The Solar System in November
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.
THE SUN and PLANETS in November, Rise & Set, Magnitude & Constellation
November 1 NZDT November 30 NZDT
Mag Cons Rise Set Mag Cons Rise Set
SUN -26.7 Lib 6.06am 8.03pm -26.7 Oph 5.40am 8.38pm
Merc 0.6 Lib 6.50am 9.48pm -0.6 Lib 4.49am 6.52pm
Venus -3.8 Lib 7.06am 9.49pm -3.9 Sgr 7.25am 10.50pm
Mars 1.8 Vir 5.19am 6.15pm 1.7 Vir 4.11am 5.58pm
Jup -1.9 Oph 8.38am 11.44pm -1.8 Sgr 7.09am 10.17pm
Sat 0.6 Sgr 10.17am 1.16am 0.6 Sgr 8.34am 11.32pm
Uran 5.7 Ari 7.28pm 6.08am 5.7 Ari 5.29pm 4.11am
Nep 7.8 Aqr 3.22pm 4.17am 7.9 Aqr 1.27pm 2.22am
Pluto 14.5 Sgr 10.40am 1.40am 14.5 Sgr 8.49am 11.48pm
November 1 NZDT November 30 NZDT
Twilights morning evening morning evening
Civil: start 5.39am, end 8.31pm start 5.10am, end 9.09pm
Nautical: start 5.03am, end 9.07pm start 4.29am, end 9.50pm
Astro: start 4.24am, end 9.46pm start 3.41am, end10.38pm
November PHASES OF THE MOON, times NZDT & UT
First quarter: Nov 4 at 11.23pm (10:23 UT).
Full Moon: Nov 13 at 2.34am (Nov 12, 13:34 UT)
Last quarter Nov 20 at 10.11am (Nov 19, 21:11 UT)
New Moon: Nov 27 at 4.06am (Nov 26, 15:06 UT)
PLANETS in NOVEMBER
MERCURY is too close to the Sun to observe for much of November. On the evening of the 1st at about 9pm, it will 7° above the horizon and 3° to the left of Venus, so giving a guide to Mercury. Earlier on the 1st, Mercury is stationary. It is stationary again on the 21st. Between the two dates the planet moves to the west and is at inferior conjunction on the 12th. A solar transit at this conjunction is unobservable from NZ and Australia.
VENUS starts November level with Mercury, but Venus will be moving to the east so the two separate in a few days. It remains an evening object and sets well over 2 hours after the Sun at the end of November. On the evening of the 24th, Venus will be 1.5° from Jupiter. An hour after sunset they will be some 10° above the horizon. Four evenings later, with Venus 4° above Jupiter, the two will be joined by the crescent moon, a couple of degrees below Jupiter.
MARS moves a little further up into the morning sky, rising 90 minutes before the Sun by the 30th. Early in the month Mars moves past Spica, with the two less than 3° apart on the morning of the 11th. Mars then rises only an hour before the Sun, so will be very low
JUPITER is an early evening object so will be low as the sky darkens. After the 24th when Jupiter and Venus are close, Jupiter will become the lower of the two.
SATURN is an evening object setting just before midnight by the end of November. This month's lunar occultation on the 2nd is visible from New Zealand. The disappearance behind the moon Earth-lit limb is observable but occurs during evening twilight for the South Island. The reappearance is about hour later but takes place at the sunlit limb.
PLUTO, like Saturn, is in Sagittarius, the two planets are less than 4° apart at the end of the month.
URANUS is an evening object. The almost full moon is 4° from the planet on the 11th.
NEPTUNE, is in Aquarius setting well after midnight. Its apparent motion is to the west until it is stationary on the 28th. Its motion then reverses to the normal east.
POSSIBLE BINOCULAR ASTEROIDS in NOVEMBER
November 1 NZDT November 30 NZDT
Mag Cons transit Mag Cons transit
(1) Ceres 9.2 Oph 4.16pm 9.2 Sgr 3.11pm
(4) Vesta 6.7 Tau 2.09am 6.8 Cet 11.46pm
(9) Metis 8.7 Psc 12.41am 9.4 Psc 10.26pm
(29) Amphitrite 9.2 Psc 11.29pm 9.8 Psc 9.26pm
CERES gets low in the evening sky. Venus passes the asteroid on the 30th, with Ceres 2° to the upper left of Venus at 10 pm.
VESTA is at its brightest being at opposition on November 12. It moves from Taurus to Cetus on the 12th.
METIS and AMPHITRITE are evening objects moving to the west through Pisces. Amphitrite is stationary on the 27th.
-- Brian Loader
5. RASNZ Beatrice Hill-Tinsley Lecture Series
The remaining lectures by Babak A. Tafreshi in the 2019 Beatrice Hill Tinsley Lecture series, funded by the RASNZ Lecture Trust Inc, are at:
Dunedin (Dunedin Astronomical Society): October 28, time 4 p.m.
Venue: Otago Museum, Hutton Theatre
Admission charge: No charge, but donations to defray costs accepted.
Wanganui (Wanganui Astronomical Society): October 30, time 7.30pm
Venue: Concert Chamber, Whanganui War Memorial Hall, Watt Street.
Admission charge: $5pp, Family $10
New Plymouth (New Plymouth Astronomical Society): October 31, time 7:30pm
Venue: Spotswood College Staffroom
Admission charge: Adults $10, Children Free
Event details and bookings: Cash Door Sales Only - No EFTPOS
For more information, see - https://www.rasnz.org.nz/rasnz/beatrice-hill-tinsley-lectures.
6. Andromeda Stardate November 1-3
The Andromeda Stardate is an astronomical festival to be held at Stonehenge Aotearoa in the Wairarapa. The program includes lectures, workshops, barbecues, movies, live music and observing sessions. It begins on Friday afternoon November 1st and runs through to Sunday 3rd. Overnight camping and caravan sites are available.
Registration Fee: (all or part of Andromeda Stardate 2019)
Adults: $30; young persons (5 to 15 years) $5; children (under 5): free. Camping Fee for weekend $10 per tent or caravan per night.
To book your place or for further information phone (06) 377 1600,
or visit our web page: www.stonehenge-aotearoa.co.nz
-- Kay Leather, Treasurer, Phoenix Astronomical Society
7. Burbidge Dinner - November 22
The Auckland Astronomical Society's Burbidge Dinner 2019 is on
Friday 22 November 2019.
Start Time: 7:00pm (doors open at 6:30pm)
Venue: Ellerslie Events Centre, Pakuranga Hunt Room.
After Dinner Lecture by Professor Joss Bland-Hawthorn, (Director, Sydney Institute of Astronomy, University of Sydney) "The Galactic Centre - a Window into the Future". See the lecture abstract at
https://www.astronomy.org.nz/new/public/eventcalendar.aspx
As well as our guest speaker there will be the prize-giving for the New Zealand Astrophotography Competition including the Harry Williams Trophy for the supreme winner, and the Beaumont Writing Prize. A spectacular venue, great meal, cash bar and ample free parking.
Tickets: $65 pp, earlybird price of $60.00 is available until 31st October includes a buffet dinner.
Tickets can be booked: - by email at events@astronomy.org.nz -by phone to Niven on 021 935 261 or Bill on 021 225 8175
-- From the Auckland Astronomical Society's website.
8. NZ Astrophotography Weekend - December 7-9
At the Foxton Beach Bible Camp, Foxton Beach, Horowhenua.
The Horowhenua Astronomical Society is hosting the sixth New Zealand Astrophotography Weekend. Held in the lower North Island it is an annual event dedicated to astrophotography in a wonderful dark-sky location. It is open to everyone interested in astrophotography - from beginners to advanced. Come along and share your knowledge, tips and experiences
All sorts of astrophotography can be undertaken - solar-system/nightscapes/deep-sky.
The weekend shall consist of: practical astrophotography, image processing, presentations, bring-and-buy, fish and chips dinner, late-night movies. Everyone is encouraged to bring along their own telescopes, binoculars, mounts, cameras, etc. however basic they might be.
See www.nzapw.org.nz for costs and registration details.
Please book early so we know the numbers.
-- Steve Lang
9. Variable Star News
Eclipse of BL Tel
Algol variables are eclipsing binary stars that are detached; the period of eclipse is determined by the orbital period of the star. Eclipse characteristics are usually a period of a few days or less and a small magnitude change of a magnitude or two. The Algol type variable BL Tel is special because it has a long period a bit over two years (estimate 778 days) and also a large decrease in brightness of mag 2.5 (from about mag 7.0 to about mag 9.5) making it a relatively easy star to monitor. The duration of the eclipse is about two months.
BL Tel will be undergoing eclipse about the time this Newsletter is distributed. BL Tel has been the subject of a long running campaign to observe these eclipses; 8 eclipses were observed in the interval from 1983 and 2000. The monitoring has continued under VSS (for information refer https://www.variablestarssouth.org/project-bl-tel-eclipse/). The star will move into the southwestern twilight about mid-eclipse meaning the later part of the event will not be observable
BL Tel is also special as one of the stars is an intrinsic variable; recently Dave Blane has been making observations of these small (range about 0.2 mags) out of eclipse variations.
Short Period Pulsator Section
The AAVSO is setting up a new section to coordinate work on “short term pulsators” defined as stars that have light pulsations from internal changes within the star and short periods of a few hours to ten days or so. Short period pulsators (SPP) include a number of different variable star types, including Cepheids, RR Lyrae stars, and delta Scuti stars For many of these variable stars the light curve is regular from cycle to cycle but for others the light curve varies in height and shape from cycle to cycle ? called the Blazhko effect after the Russian astronomer who first drew attention to it. Multiple pulsation periods which alternately interfere or reinforce each other can result in very complex light curves; multi-periodic stars like these must be observed frequently over weeks or months to provide enough data to determine the periods involved.
For information on the SPP group go to https://www.aavso.org/aavso-short-period-pulsator-section. Visit AAVSO SPP Program page if you are interested in choosing observing targets.
AAVSO Looking to the Future
The AAVSO has been undertaking a consultation amongst its members on the future shape of the organisation (see their “Planning AAVSO’s future” forum.). AAVSO Director Stella Kafka and President Gordon Myers reached out to Variable Stars South (VSS) and arranged a teleconference on Saturday 12th October in which Mark Blackford and two other VSS members took part. Several topics were raised including what tasks are most usefully done by amateurs now and in the near future given the likely dramatic impact of all-sky surveys and robotic telescope installations. For sure more will come out of the on-going dialogue as discussion continues. The next step will be the AAVSO Annual Conference being held 18-21 October at Las Cruces New Mexico.
-- Alan Baldwin
10. Star Parties in 2020
The following star parties are planned for 2020:
Central Star Party: Thursday 16th to Sunday 19th of January at the Tuki Tuki Camp site in the Hawkes Bay. https://censtar.party/
Stardate North Island: Friday 21st to Sunday 23rd February at Stonehenge, Carterton. Check Phoenix website - http://www.astronomynz.org/
Stardate South Island: Late February. At Staveley, South Island. Keep an eye on https://cas.org.nz/
Stargazers Getaway 2020 Camp Iona, September 18th, 19th and 20th 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 10 – Monday 13 April. For more details see http://nacaa.org.au/2020/about
-- Mostly from 'Keeping in Touch' #34, 27th Sept 2019.
11. 2020 Conference and RASNZ Centenary
The 2020 Conference will be held Friday 8 - Sunday 10 May 2020 in Wellington. The Wellington Astronomical Society is hosting the Conference.
The Conference venue is the Wharewaka Function Centre located on the waterfront just 2 minutes walk from Te Papa.
As the programme will commence at the earlier than usual time of 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 conclude mid-afternoon on Sunday.
Planning for this event is progressing and further details will be announced in the near future once they are confirmed. In the meantime please mark the above dates in your calendar and consider participating in this Conference as RASNZ celebrates its centenary.
-- Glen Rowe, Chair, Standing Conference Committee.
12. RASNZ 100 Programme
The RASNZ Council is pleased to announce its RASNZ 100 Programme to support Affiliated Societies celebrating the RASNZ's Centennial year in 2020. The programme encourages Affiliated Societies to promote astronomy within their regions to raise the profile of the Society, the RASNZ and astronomy in general. The RASNZ is providing up to $500 to each Affiliated Society to support RASNZ 100 events run by Affiliated Societies. For more information, see https://www.rasnz.org.nz/groups-news-events/rasnz-100-events
-- From 'Keeping in Touch' #34. 27th Sept 2019
13. Brashear Lens History
A history of the lens in the Brashear telescope now reassembled at Lake Tekapo's Dark Sky Project is detailed in "A tale of three telescopes: the John A. Brashear Company and its 46-cm objective" by Richard Taibi.
The paper is in the Journal of Astronomical History and Heritage, Volume 22, No.2, p.247, and can be viewed at
http://www.narit.or.th/en/files/2019JAHHvol22/2019JAHH...22..247T.pdf
The Newsletter editor can pass along a pdf if the above link doesn't work.
14. Comet Borisov's Size
A paper by David Jewitt and Jane Luu provides an estimate of the size of Comet Borisov's nucleus. The paper's abstract follows.
We present initial observations of the interstellar body 2I/Borisov taken to determine its nature prior to the perihelion in 2019 December. Images from the Nordic Optical Telescope show a prominent, morphologically stable dust coma and tail. The dust cross-section within 15,000 km of the nucleus averages 130 sq. km (assuming geometric albedo 0.1) and increases by about 1 percent per day. If sustained, this rate indicates that the comet has been active for 100 days prior to the observations. Cometary activity thus started in 2019 June, at which time C/Borisov was at 4.5 AU from the Sun, a typical distance for the onset of water ice sublimation in comets. The dust optical colors, B-V = 0.800.05, V-R = 0.470.03 and R-I = 0.490.05 are identical to those of a sample of (solar system) long-period comets. The colors are similar to those of 1I/(2017 U1) 'Oumuamua, indicating a lack of the ultrared matter that is common in the Kuiper belt, on both interstellar objects. The effective size of the dust particles is estimated as 100 microns, based on the length of the dust tail and the 100 day lifetime. With this size, the ejected dust mass is of order 1.3e7 kg [13,000 tonnes] and the current dust mass loss rate 2 kg/s. We set an upper limit to the nucleus radius using photometry of <3 .8="" 0.1="" a="" again="" albedo="" argument="" be="" br="" few="" for="" however="" hundred="" in="" km="" likely="" meters="" much="" must="" nucleus="" radius.="" show="" smaller="" statistical="" that="" the="" to="" use="" we="">
The paper "Initial Characterization of Interstellar Comet 2I/2019 Q4 (Borisov)" by David Jewitt and Jane Luu is at https://arxiv.org/abs/1910.02547
---------
The small size of the nucleus raises the possibility that it will disintegrate during its perihelion. If so then the comet could be briefly bright.
---------
Syuichi Nakano, Sumoto, Japan, has computed the asymptotic
points of 2I/Borisov. The original asymptotic point from whence the comet came on its way to the solar system is located at R.A. = 2h11m.2m, Decl. = +59d26' (equinox J2000.0), which is in the constellation Cassiopeia. The comet is headed toward the future asymptotic point at R.A. = 18h21m.5, Decl. = -51d59' (which is in Telescopium).
-- From Central Bureau Electronic Telegram No. 4679, 2019 October 18
15. Fast Radio Burst Plumbs Galaxy's Halo
In November 2018 the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope pinpointed a fast radio burst, named FRB 181112. Follow-up observations with European Southern Observatory's Very Large Telescope (VLT) and other telescopes revealed that the radio pulses passed through the halo of a massive galaxy on their way toward Earth. This finding allowed astronomers to analyse the radio signal for clues about the nature of the halo gas.
Astronomers still don't know what causes fast radio bursts and only recently have been able to trace some of these very short, very bright radio signals back to the galaxies in which they originated. "When we overlaid the radio and optical images, we could see straight away that the fast radio burst pierced the halo of this coincident foreground galaxy and, for the first time, we had a direct way of investigating the otherwise invisible matter surrounding this galaxy," said coauthor Cherie Day, a PhD student at Swinburne University of Technology, Australia.
A galactic halo contains both dark and ordinary-or baryonic-matter that is primarily in the form of a hot ionised gas. While the luminous part of a massive galaxy might be around 30 000 light years across, its roughly spherical halo is ten times larger in diameter. Halo gas fuels star formation as it falls towards the centre of the galaxy, while other processes, such as supernova explosions, can eject material out of the star-forming regions and into the galactic halo. One reason astronomers want to study the halo gas is to better understand these ejection processes which can shut down star formation.
J. Xavier Prochaska, professor of astronomy and astrophysics at the University of California Santa Cruz and lead author of the study noted that "This galaxy's halo is surprisingly tranquil. The radio signal was largely unperturbed by the galaxy, which is in stark contrast to what previous models predict would have happened to the burst."
The signal of FRB 181112 was a few pulses, each lasting less than 40 microseconds (10 000 times shorter than the blink of an eye). The short duration of the pulses puts an upper limit on the density of the halo gas because passage through a denser medium would broaden the duration of the radio signal. The researchers calculated that the density of the halo gas must be less than 0.1 atoms per cubic centimetre (equivalent to several hundred atoms in a volume the size of a child's balloon). [A cc of air at sea level contains 2.7x10e19 molecules.]
The study found no evidence of cold turbulent clouds or small dense clumps of cool halo gas. The fast radio burst signal also yielded information about the magnetic field in the halo, which is very weak - a billion times weaker than that of a refrigerator magnet.
At this point, with results from only one galactic halo, the researchers cannot say whether the low density and low magnetic field strength they measured are unusual or if previous studies of galactic halos have overestimated these properties. Prochaska said he expects that ASKAP and other radio telescopes will use fast radio bursts to study many more galactic halos and resolve their properties.
-- Abridged from the ESO press release at https://www.eso.org/public/news/eso1915/ passed along by Karen pollard.
16. Marsquakes on Line
Put an ear to the ground on Mars and you’ll be rewarded with a symphony of sounds. Granted, you’ll need superhuman hearing, but NASA’s InSight lander comes equipped with a very special “ear.” The Insight spacecraft’s exquisitely sensitive seismometer, called the Seismic Experiment for Interior Structure (SEIS), can pick up vibrations as subtle as a breeze. The instrument was provided by the French space agency, Centre National d’Études Spatiales (CNES), and its partners.
SEIS was designed to listen for marsquakes. Scientists want to study how the seismic waves of these quakes move through the planet’s interior, revealing the deep inner structure of Mars for the first time. But after the seismometer was set down by InSight’s robotic arm, Mars seemed shy. It didn’t produce its first rumbling until this past April, and this first quake turned out to be an odd duck. It had a surprisingly high-frequency seismic signal compared to what the science team has heard since then. Out of more than 100 events detected to date, about 21 are strongly considered to be quakes. The remainder could be quakes as well, but the science team hasn’t ruled out other causes.
Put on headphones to listen to two of the more representative quakes SEIS has detected. These occurred on May 22 (the 173rd Martian day, or sol, of the mission) and July 25 (Sol 235). Far below the human range of hearing, these sonifications from SEIS had to be speeded up and slightly processed to be audible through headphones. Both were recorded by the “very broad band sensors” on SEIS, which are more sensitive at lower frequencies than its short period sensors. The Sol 173 quake is about a magnitude 3.7; the Sol 235 quake is about a magnitude 3.3:
* https://soundcloud.com/nasa/quake-sol-173
* https://soundcloud.com/nasa/quake-sol-235
Each quake is a subtle rumble. The Sol 235 quake becomes particularly bass-heavy toward the end of the event. Both suggest that the Martian crust is like a mix of the Earth’s crust and the Moon’s. Cracks in Earth’s crust seal over time as water fills them with new minerals. This enables sound waves to continue uninterrupted as they pass through old fractures. Drier crusts like the Moon’s remain fractured after impacts, scattering sound waves for tens of minutes rather than allowing them to travel in a straight line. Mars, with its cratered surface, is slightly more Moon-like, with seismic waves ringing for a minute or so, whereas quakes on Earth can come and go in seconds.
SEIS has no trouble identifying quiet quakes, but its sensitive ear means scientists have lots of other noises to filter out. Over time, the team has learned to recognize the different sounds. And while some are trickier than others to spot, they all have made InSight’s presence on Mars feel more real to those working with the spacecraft.
“It’s been exciting, especially in the beginning, hearing the first vibrations from the lander,” said Constantinos Charalambous, an InSight science team member at Imperial College London who works with the SP sensors. “You’re imagining what’s really happening on Mars as InSight sits on the open landscape.”
Charalambous and Nobuaki Fuji of Institut de Physique du Globe de Paris provided the audio samples for this story, including the one below, which is also best heard with headphones and captures the array of sounds they’re hearing: https://youtu.be/m9cCuW9nIQg
Wind gusts can also create noise. The team is always on the hunt for quakes, but they’ve found the twilight hours are one of the best times to do so. During the day, sunlight warms the air and creates more wind interference than at night.
Evening is also when peculiar sounds that the InSight team has nicknamed “dinks and donks” become more prevalent. The team knows they’re coming from delicate parts within the seismometer expanding and contracting against one another and thinks heat loss may be the factor, similar to how a car engine “ticks” after it’s turned off and begins cooling.
You can hear a number of these dinks and donks in this next set of sounds, recorded just after sundown on July 16 (Sol 226). Listen carefully and you can also pick out an eerie whistling that the team thinks may be caused by interference in the seismometer’s electronics:
* https://soundcloud.com/nasa/dinks-and-donks-sample
See the original text & graphics at:
https://www.jpl.nasa.gov/news/news.php?release=2019-195
-- From the Jet Propulsion Laboratory press release forwarded by Karen Pollard. 17. Kingdon-Tomlinson Fund
The RASNZ is responsible for recommending to the trustees of the Kingdon
Tomlinson Fund that grants be made for astronomical projects. The grants may be to any person or persons, or organisations, requiring funding for any projects or ventures that promote the progress of astronomy in New Zealand. The deadline for this round of the Kingdon-Tomlinson Grants is Friday 1st November 2019. Full details are set down in the RASNZ By-Laws, Section J. Information on the K-T Fund is at
http://rasnz.org.nz/rasnz/kt-fund
Send applications to the RASNZ Executive Secretary at rasnz.secretary@gmail.com.
The application form at
http://rasnz.org.nz/Downloadable/RASNZ/KT_Application2019.pdf
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
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