exocast

In this most excellent 100th episode of Exocast from the team we bring you the latest in exoplanet research and news.

Hannah and Andrew cover news from the TRAPPIST system. Hannah will dive into the JWST results that have come out about this very famous system of seven Earth-sized rocky planets. Two papers look to the mid-infrared to measure the light directly from the planets b and c in emission – finding that they likely do not have an atmosphere possibly stripped by their stars radiation. The first spectroscopic measurements of TRAPPIST show that the star itself is going to be the “star” of the show with stellar contamination dominating the data. But we remain optimistic! 5 more planets await their observations and there is much to learn about this small cool star.

Andrew covers a paper that discusses the feasibility of detecting some biosignatures from TRAPPIST-1 d and e using JWST. This “experimental sandbox” for astrobiology makes TRAPPIST the perfect place to start. The theoretical studies uses a climate model to ask the question: what could we see if it was there? The model looks for methane, carbon dioxide, oxygen, ozone, methyl chloride, and methyl mercaptan; with methane and carbon dioxide pair being the best combo to suggest something out of equilibrium possibly caused by life. But is the question we should be asking, is this the right system to look for life at all? – what do you think?

Hugh then takes us back to formation in a dramatic fashion with an astronomical mystery. A young star has been dimming and almost disappeared for over a year with variations in the starlight over nearly 1000 days. The question simply is: What is going on? It is almost always something to do with dust. This can be seen over different wavelengths showing the dust interacting with the light. But in this case the exciting new result is that about 3 years before the dimming happened, a bright event was seen in the system. What the team found through simulations suggest that there was a giant collision of planets in that system that created the bright event and then the debris field blocking the light. Space is really remarkable!

100 episodes is a huge milestone and as always Hugh, Hannah, and Andrew could not do this show without you! Thank you for listening.

Exocast is edited by Fergus Hall. You can help support Exocast and the team at BuyMeACoffee.com/exocast, and get yourself some Exocast merch at exocast.threadless.com

In this episode the team cover some of the latest exoplanet news stories. This month Hugh covers the first JWST’s transmission spectrum of a small planet, validating and characterising the exoplanet LHS 475b. Hannah discusses some preliminary work from JWST, including phase curves from WASP-121b and WASP-43b, that reveal the capabilities and quirks of the instruments onboard. Andrew breaks the rules by discussing three papers, 2 of which are closely connected, on the general topic of the potential for serpentinization as a possible source of energy for microbial metabolisms around hydrothermal vent systems.

• Hugh’s paper: A JWST transmission spectrum of a nearby Earth-sized exoplanet (arxiv pre-print, submitted to Nature Astro)
• Hannah’s papers:
  • A JWST NIRSpec Phase Curve for WASP-121b: Dayside Emission Strongest Eastward of the Substellar Point and Nightside Conditions Conducive to Cloud Formation
  • A First Look at the JWST MIRI/LRS Phase Curve of WASP-43b (arxiv pre-print)
• Andrew’s papers:
  • Diverse geochemical conditions for prebiotic chemistry in shallow-sea alkaline hydrothermal vents
  • Deep-branching acetogens in serpentinized subsurface fluids of Oman
  • Microbial biosignature preservation in carbonated serpentine from the Samail Ophiolite, Oman

Exocast is edited by Fergus Hall, you can find more of his work www.fergushallmusic.com.

If you would like to support the show consider donating on our buymeacoffee.com/exocast page, all donations matter and help keep Exocast going. You can also get your hands on Exocast merchandise at exocast.threadless.com

The latest news hot off the Exocast news desk for July/August 2022, another exciting month for exoplanet science:

• Andrew takes some time to discuss the life and influence of Dr James Lovelock, the co-originator the Gaia Hypothesis, who died recently. His news this month takes the form of two independent but neatly connected papers on the topic of ‘chirality’: ‘The Chiral Puzzle of Life’ by Globus and Blandford, and ‘Directional Aspects of Vegetation Linear and Circular Polarization Biosignatures‘ by Patty et al.
• Hannah summarises ‘Chemical Abundances for 25 JWST Exoplanet Host Stars with KeckSpec’ by Polanski et al. in anticipation of the publication of a larger elemental abundance catolog derived from Keck/HIRES optical spectra.
• Hugh covers Zhang et al‘s ‘Detection of Atmospheric Escape from Four Young Mini Neptunes’ that details the smallest and youngest planets for which escaping atmospheres have been detected, with implications for the exoplanet ‘radius valley’.

What did you think of the papers/news discussion? Join in the conversation in the comments below, and find us on Twitter. If you want to support the Exocast Podcast then you can Buy us a Coffee, or get your own merchandise at exocast.threadless.com. A big thank you to Tobias Andropolis for recently buying 7 coffees!

Exocast is edited by composer/muscian Fergus Hall (https://fergushallcomposer.com) and supported in part by funding from the University of Bristol via H.Wakeford starter funds.

In this episode the Exocast gang are privileged to be joined by veteran exoplaneteer Dr Mark Marley from NASA Ames. During a nearly hour-long discussion, we probe Mark’s experience of early exoplanet discovery and characterisation efforts in the 1990s, his work on clouds and atmospheric circulation models, ‘ice’ giants, brown dwarfs, his leadership role with the LUVOIR space telescope concept, as well as his cheerleading efforts during the Exocup.

We also welcome back our Adopt a Planet segment with our guest picking a returning favourite, 51 Eri b. Listen to the segment at the end of the show to hear Mark’s reasons for picking this fascinating planet. Will being adopted twice help 51 Eri b’s chances in the Exocup this year...?

Mark Markley is a Research Scientist at NASA’s Ames Research Center in Mountain View, CA. who earned his PhD in Planetary Science from the Lunar and Planetary Laboratory (LPL) at the University of Arizona in 1990. After a postdoc studying planetary atmospheres at NASA Ames he began a faculty position in Astronomy at New Mexico State University in 1993, before returning to Ames in 2000 as a civil servant scientist. Mark will return to the University of Arizona to take up leadership of the LPL and Department of Planetary Sciences in mid-May 2021. He tweets from @astromarkmarley, and you can find more info about his work at his NASA webpage and ADS publication list.

Remember you can join in the discussion in the comments below, and find us on Twitter. If you want to support the Exocast Podcast then you can Buy us a Coffee, or get your own merchandise at exocast.threadless.com

This month Hugh, Andrew, and Hannah talk to astrophysicist, folklorist, and science communicator Moiya McTier. Moiya is an NSF graduate researcher at Columbia University in New York City and works to understand exoplanets from a galactic perspective.

The Exocast team talks to Moiya about work from measuring the topography on an exoplanet by the effect that mountains and other features have in transit, all the way up to how the stars in the Milky Way are moving and the effects those might have on their planets. The blended approach Moiya takes to science with a look too folklore and the way we perceive our universe gives a new spin to the way we can view and measure exoplanets and our universe. We chat about how to best communicate what astronomy is to others and how to make the right connections.

We also take the opportunity to talk to Moiya about what it is like to be a black woman in the astronomy community. The value of familiarity and shared experience in any field is important and we need to be more aware of ourselves and others to make this field more inclusive. See, think, act.

You can find more by Moiya McTier on YouTube, Twitter @GoAstroMo, and follow Exolore a podcast on world building.

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