AAS notes

The first meeting I was able to attend in full was the Exhibitor Showcase: The Hubble Space Telescope at 30: Awesome Discoveries and Innovation

-Hubble is in really good shape.
-Wolf-Rayet is pronounced Wolf-Rie-ay.
-Astronomers would fly up into space to do observation in the 1960s plans! Space station space telescope!
-Servicing improvements have dramatically improved image quality even after the 1st servicing mission.
-Hubble is still in good condition and doing cutting edge science.
-Hubble helped to realize many modern cosmological problems like an accurate distance ladder and supermassive black holes in galaxy cores. Faint Object Spectrograph showed that M87 gas had a red and blue shifted aspect, implying it has a SMBH.
-IR pillars of creation is real cool--the pullars become ghostly and transparent.
-Hubble has the only UV capability of any space telescope now or near future.
-Hubble showed galaxy mergers are a dominant force in galactic evolution
-More than a million observations!
-Hubble observed a LIGO merger from a kilonova source in a distant galaxy.
-Multimessenger astronomy.
-Gravitational lensing is a common hubble observation.
-500,000,000 years after big bang: very very dim galaxy hubble observed using gravitational lensing.
-using quasar spectrum to study material cycling in and out of galaxies.
-hubble is refining the Hubble Constant of expansion by making precise cepheid and 1a supernovae measurements.
-hubble constant measured from standard candles does not match the constant predicted by big bang cosmology.
-hubble is measuring exoplanetary atmosphere spectra. Hubble was the one that detected super-earth water vapor.
-hubble coexists and supports space probes.
-hubble archive provides over half of new publications.
-preparatory observations for JWST.
-tactile-encoded images for visually impaired.
-WFISRT has a larger mirror than hubble, slightly. Didn't expect that.
-"we're entering the golden age of astronomy" is overused, but we really are.
-complimentary uses of observatories and probes is wonderful, better than using any on their own.

question: how long does hubble have left? could it be serviced with robots if we never have something like a Space Shuttle again?
answer: Continuingly monitoring health of instruments including gyroscopes as well as science instruments. lots can be done from the ground. Hubble should be healthy from 2025 and beyond. There is no NASA plan to service hubble.

random bit from poster: stars form in giant molecular clouds which are "supersonically turbulent and magnetized"

plan to attend Extrasolar Planets II oral session

Hydrodynamic Study of Radiative Cooling and Escape of Metal Species in Hot Jupiter Atmospheres
-Magnesium and Iron detected in hot jupiter transmission spectra
-escaping atmosphere models must account for metal loss
-extreme-uv flux, energy-limited escape.
-one of the other presenters is not muted!
-new model starts at 1 planetary radius at 1 microbar.
-magnesium plays a role in radiative cooling, which subtly affects atmosphere loss. Peak temperature of atmosphere decreases with magnesium accounted for.
-iron cooling is more complicated than mg cooling.
-tidal forces dominate mass loss, and rapid rotation is not an effect here.

An Update on the Transmission Spectra of Sub-Neptune Exoplanets
-subneptunes seem to be far more common that jovians
-we want to understand these smaller planets.
-what are their atmospheres made of? does it fossilize fingerprints from their formation?
-warm neptunes: cooler than ~1000 K
-warmer neptunes have stronger spectral features, cooler have weaker features
-aerosol formation in warmer?
-aerosols turn on from 1100 to 600 K then clear out at 350K and cooler temperatures.
-aerosol models match hot jupiter observations. only one out of several hot jupiters have clear atmos.
-warm jupiter models match warm neptune models very well
-hazes are thinnest at highest temp, because they form from photolysis of methane.

Smaller than expected bright-spot offsets in Spitzer phase curves of the hot Jupiter Qatar-1b
-I was eating lunch so couldn't pay attention.
-jupiters have eastward hot spots
-magnetic drag in atmo can slow down winds

 Survival of Primordial Planetary Atmospheres: Mass Loss from Temperate Terrestrial Planets
-core accretion: giant impacts dominate atmosphere mass loss.
-Photodissociation and ionization from shorter and uv light.
-can't remove 2% of earth's mass in hydrogen by photoevaporation, requires giant impacts.
-hybrid model can remove primordial atmo (giant impacts like the moon-forming impact plus photoevaporation)
-need a better understanding of mass loss from M dwarfs vs G dwarfs for kepler exoplanets
-moon forming impact might strip all of the primordial atmo, or 50% or 20%, no good consensus.

Robust Quantification of Abiotic CH4 and O3 in Atmospheres of Potentially Habitable Terrestrial Planets Orbiting a 3300K M-Dwarf Host
-planets in low hz orbits may have lots of water compared to rapid rotator. perhaps 1000x enhanced water.
-thick clouds at substellar point, making low tidal locked hz planets cooler than Earth.
-Molecules in upper atmo get photodissociated.
-1D atmo model using boundary conditions, chemistry, and eddy diffusion.
-simulated active and inactive star spectrum.
-high CH2 and C2H6, absent in UV cases.
-lost concentration due to interruptions about halfway through and stopped being able to follow.

Cloud Atlas: The rotational modulation of a rare planetary-mass object at the end of L/T transition
-Cloud are the result of complicated processes in planetary atmospheres, not just haze blocking out transmission.
-how do cloud structures vary with temperatures and gravities
-brown dwarves and gas giants share similar temperatures and gravity ranges.
-drastic L/T transition is major evidence of cloud evolution
-time series spectroscopy probes different levels in atmospheres
-GU Psc b located at end of L/T transition. 1000K temperature. >8hours rotation.
-clouds are heterogenously distributed in L/T spectral types.
-silicate clouds in LT dwarfs
-internal heating vs external heating results in same cloud chemistry--local equilibrium conditions, clouds form at similar temp and pressure level. Will still change atmo dynamics and cloud circulation patterns, but cloud formation itself seems the same between hot jupiters and brown dwarfs.

Keeping M-Earths Habitable in the Face of Atmospheric Loss by Sequestering Water in the Mantle
-30% of M dwarfs should have at least one rocky planet.
-M dwarves are very active in XUV and Xray. Photodissociate water molecules and drive water loss, or even erode atmospheres entirely
-Hide water in mantle, and gas it into surface once loss diminishes.
-timescale for outgassing must be slower than the M dwarf ages.
-water in the mantle is degassed to the surface by volcanism and is subducted from the ocean into the mantle.
-after stellar activity calms down, water has been lost, but eventually most of the water loss turns into mantle/surface cycle
-increase water loss by 10x, surface becomes dessicated, eventually water becomes lost even from the mantle, until very late when it may become a dry "Dune" world.
-M-Earths can retain surface water if there's enough to start with.
-water in the mantle can rehydrate a surface at late times.
-"dune" world means martian like wetness. Lakes are unlikely, more subterranean or polar ice. 0.1% of earthly water.
-mantle water cycle timescales: not sure if they are much shorter than stellar timescales.

Testing Earth-like Atmospheric Evolution on Exo-Earths
-Using Earth's geological history as a guide for exoearth evolution.
-oxygen is a strong biosignature
-deep spectroscopic characterization of indivudal planets: is this planet habitable? inhabited?
-statistical exploration: what are the requirements for habitablity? how to planets coevolve with life?
-if other inhabited planets evolve like this, we expect older planets to have more oxygen.
-maybe earth is rare and most planets don't evolve like earth.
-should be an age-oxygen correlation. Larger fraction of oxidized atmospheres with age.
-could this correlation be detected with upcoming missions?
-statistical test to determine how many planets would need to be discovered to have oxygen to prove this age-oxygen correlation. This should be able to be done in the next few decades. This is testable.
-test to see if oxygen is a valid biosignature. if we see that oxygen evolves with time like the earth for many planets, that implies it is a biosignature
-must look at <2Gy planets.
-extinction events would be an age-oxygen correlation look more interesting and require a better sample size to pick it apart.
-interesting to think about the history of life on planets just from an atmospheric planetary science perspective! It is almost comically reductive, but very interesting.
-far-UV is necessary because oxygen implies ozone, and ozone is detectable in UV.