The 2nd presentation in today’s first #AAS238 presser looks at ways to find planets by looking at the composition of stars.

A Statistical Search for Chemical Signatures of Planet Formation in Sun-like Stars
Jacob Nibauer (University of Pennsylvania)

There was a lot of chemistry in this talk, but the bottom line is this: If you have two stars that formed from the same kind of stuff, then the star that forms rocky worlds will have less of the stuff needed to make those planets then a star that didn’t make planets.

To test this concept, need to cross-match Kepler & TESS exoplanet hosts to identify if they do or don’t show expected depletions, need to consider binaries.

I’m curious if we have enough data to consistently say, here are rocky worlds, & here aren’t rocky worlds?

Will ask.

Got answer: Detections are preferential to short orbit & big planet radii. This isn’t enough… yet. But we can see if a set of “These stars definately have planets” are different from a randomly selected set of stars.

Can also look at depleted vs not depleted in general.


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More from @starstryder

9 Jun
First presentation looks at CHIME and Fast Radio Bursts!

Fast Radio Bursts: From a Handful to Hundreds with CHIME/FRB
Kiyoshi Masui (MIT), Alex Josephy (McGill University) & Mohit Bhardwaj (McGill Univ.)

CHIME is a cool Canadian radio array nicely tuned to the colors of radio light where whatever is causing Fast Radio Bursts (FRBs) are doing their primary bursting.

We really don’t know a lot about FRBs. They are (astronomically) pretty new discoveries, every obs is needed.

FRBs are brief, & to see them you need to either be looking exactly right by luck, or looking everywhere by design.

CHIME uses sophisticated data processing to look at most of visible sky simultaneously, and tune in fast.


In just a couple years, known catalogue grew a lot!
Read 10 tweets
8 Jun
Ok, seminar stuff about this giant new shiny IR telescope that may or may not launch later this year.

So far, it’s the same info seen since I was in grad school, but with better images & animations.

Reminder, JWST was supposed to launch in 2007.

No, I’m not bitter.

This presentation is acknowledging how ALMA is really doing amazing science that we really thought would have to wait until JWST launched.

Scientists will find a way to science!

This ground-based array is using its limited wavelengths to see star+Planet formation.

From the ground, our atmosphere blocks & blurs many molecular lines - like water - but if JWST works (how do you say “break a leg" in telescope?) it will see more details, & will see what science data is blocked by our atmosphere’s water.

We really need to do IR from space.

Read 14 tweets
8 Jun
The first presentation of this presser is:

The Molecular Content of Planetary Nebulae: The Next Level
Kate Gold & Deborah Schmidt

and we are starting with super pretty images. I *need* to find this mosaic of Planetary Nebulae.

We know basics of Planetary Neb (PN). Middle mass stars stop fusing materials in their core, exhale their atmospheres into nebulae, & that material gets recycled into future gen of stars. Since the PN are made of material enriched in the star, they have lots of MOLECULES.

In this study, Gold & Schmidt observed a series of PN with different ages to see what is in them over time. They looked specifically for HCN & HCO+ in 30 PN and found they are common & seem to date back to star. This means molecules form in star & survive nebula formation.

Read 4 tweets
7 Jun
From galaxy mergers we now turn to Black Hole mergers.

TMaximum Black Hole Mass Across Cosmic Time
Jorick Vink

This is a weird system with 2 larger then necassarily steller mass systems merging into an intermediate mass Black Hole!

Q - What is max mass of Star/BH?

1/ Image
It was thought that as steller masses increase, steller winds increasm causing more and more material to be lost through wind, and lower the max mass of the star. BUT… is this always true?

No - stars with lots of metals have more possible spectral lines and lower max mass

On the other hand, if you have very very low metallicity stars - stars missing heavy atoms - then stars can get much much bigger, and bigger black holes can result from the evolution of a single star.

Stars even up to 100 solar masses!

This can lead to the 85 solar mass BH

Read 5 tweets
7 Jun
Well, I made the release I wanted:

A Merging Galaxy Triple Hosting a Potential Dual Active Galactic Nucleus
Jonathan Williams

Basically - models being done to sort how systems merge and evolve and now compared to Data of 3x merger

This is a striking system. The bright cores are 9100ly apart and appear to be AGN.

The fainter system appears to be a dwarf galaxy that has perhaps already passed between the other two cores.

2/ Image
Specral imaging in Halpha allows velocities to be mapped thanks to the Doppler shifting of the moving gas spread throughout the system.

3/ Image
Read 4 tweets
7 Jun
Now for release I most looked forward to:

Eta Carinae's Change of State as Seen by Hubble from 1998 to 2021
Kris Davidson, University of Minnesota

Eta Car failed to go SN in the past but will likely go boom in the future. AND it’s only 7500ly away.

1/ Image
Davidson reminds us at #AAS238 presser that Eta Car was one of the brightest stars in the sky… until it wasn’t. In 1800s there was a great eruption but then the star fadded away… only to slowly rebrighten again. It continues to work its way back to bright.

2/ Image
Eta Car is actually 2 stars: a giant & a companion. They orbit every 5.5 yr & have a highly elliptical orbit that causes them to get much closer every 5.5 years. In the past, during this close passing, massive star dumped so much matter on companion it blocked UV.

Read 5 tweets

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