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November 2020: A-RIP-bo

November 2020

In the show this time, we talk to Taïssa Danilovich about the chemistry of Asymptotic Giant Branch stars, Michael Wright rounds up the latest news, and we find out what we can see in the November night sky from Ian Morison, Haritina Mogosanu and Samuel Leske.

The News

This month in the news: water on the moon and getting in touch with Voyager.

Firstly, a new paper called 'Molecular water detected on the sunlit Moon by SOFIA' has been published. As the name suggests it claims the discovery of water on the sunlit part of the moon. We already have found water ice in near the moon's poles and some water in the layer of gases surrounding the moon, but this is paper focuses on water on in the sunlit part of the moon.

SOFIA, the Stratospheric Observatory for Infrared Astronomy, was observing one of the moon's craters called Clavius crater and looking for a particular signature which indicates water: a peak in emissions at a wavelength of around 6 micrometers.

The researchers made graphs of the emission where they were looking plotted against wavelength for a few micrometers around where that 6 micrometer peak was expected. The authors compare the peaks found to the spectra for various materials known to be water bearing, finding reasonable agreement and pointing out that they know of no other materials which are both reasonable to find on the moon and have this single spectral feature.

This discovery poses interesting problems when it comes to working out how come that water is there. In the NASA press release for the paper the lead author Casey Honniball is quoted, saying “Without a thick atmosphere, water on the sunlit lunar surface should just be lost to space, yet somehow we're seeing it. Something is generating the water, and something must be trapping it there."

Also in the news, a set of test commands were beamed to Voyager 2 at the end of October, which appear to have worked with no known issues.

To communicate with the craft NASA uses the Deep Space Station 43 radio antenna in Australia. However in March the telescope was stopped for repairs, the argument made was that as the equipment aged the possibility for unplanned outages of power would rise. The repair work also includes upgrades to make the telescope more reliable. Voyager could still submit data back to Earth, there are other dishes to receive that data, but DSS43 is the only antenna which can send to Voyager.

As for the upgrades, these include installing two new radio transmitters, including one to communicate with Voyager 2, as well as many other upgrades to make those work, for example cooling equipment, upgrading the electronics and the power supply.

Interview with Taïssa Danilovich

Dr. Taïssa Danilovich talks about Asymptotic Giant Branch (AGB) stars, a stage that all stars up to 10 solar masses evolve onto late in their lives before dying as white dwarfs. As these stars are relatively cool, complex molecules which would be destroyed by hotter stars can form around them. She discusses the molecules that are formed from the gas ejected by the star's solar wind, and what they tell us about the environment around the star, as well as the composition of interstellar dust. She also talks about her recent work with ALMA.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during November 2020.

Highlights of the Month

The Planets

The Stars

Southern Hemisphere

Haritina Mogosanu and Samuel Leske from the Carter Science Centre in New Zealand speaks about the Southern Hemisphere night sky during November 2020.

The evening sky of November holds the Maori asterism of Te Waka O Tamarereti, which depicts one of my favourite cultural interpretations of how the stars ended up in the night sky. Here in New Zealand, this time of the year, after sunset, we see the Milky Way surrounding the horizon; when it's like that, the galaxy here looks like a river. Move away from the light polluted cities and you should be able to clearly see it wrapping around the horizon, this is how dark the sky is in New Zealand, throughout the entire country.

Planets

Constellations

Deep Sky Objects

Odds and Ends

The Arecibo radio telescope is going to be decommissioned following some severe damage to its cables, leading to a risk of the entire telescope collapsing. As was mentioned in the September news, a cable initially snapped by August this year, tearing a gash in the telescope's surface. While it was under evaluation for repairs, another cable broke on the 6th of November, and it's been concluded that the remaining cables are likely weaker than previously believed. As a result, repairs have been deemed too dangerous; if more cables were to break during repair efforts, it might prove life-threatening to workers. The dish is now going to be decommissioned and deconstructed for safety - sad news for the radio astronomy community, who'll be losing a truly iconic telescope.

(Note: in the time since recording the presenting, Arecibo's platform has collapsed. Thankfully, the National Science Foundation have reported that nobody was injured as a result of this. Nonetheless, it's with heavy hearts that astronomers, hobbyist and professional, have to say goodbye to Arecibo. We at the Jodcast are certain that its legacy won't be forgotten.)

A group of scientists from the APOGEE experiment discovered the remnants of a galaxy within the Milky Way, thought to have collided with our galaxy early in its life. The group of stars belonging to this past galaxy were identified due to their different chemical composition and dynamics when compared with other stars in the Milky Way. The total mass of stars concerned is approximately 500 million solar masses, or roughly twice the mass of the Gaia-Enceladus/Sausage system previously discovered. The paper about this discovery can be read here.

Show Credits

News:Michael Wright
Interview:Taïssa Danilovich and Fiona Porter
Night sky:Ian Morison and Haritina Mogosanu
Presenters:Fiona Porter and Thomas Rennie
Editors:Tiaan Bezuidenhout, Lizzy Lee, Hongming Tang and Michael Wright
Segment Voice:Tess Jaffe
Website:Fiona Porter and Stuart Lowe
Producer:Fiona Porter
Cover art:View of the Arecibo radio telescope primary dish and the spherical reflector, Arecibo Observatory, Puerto Rico. CREDIT: Mario Roberto Duran Ortiz

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