Event information

Kevin's Southern California work trip

Stops: UCLA, Carnegie Observatories, IPAC-Caltech, Jet Propulsion Laboratory (JPL), UC-Riverside

Talk title: Atmospheric Retrieval of Exoplanets: Extracting Chemical Abundances from Spectra of Exo-atmospheres

Abstract: "I will review the method of atmospheric retrieval, which is a remote sensing technique borrowed from the Earth atmospheric and planetary sciences and generalised for the study of exoplanetary atmospheres. Atmospheric retrieval aims to extract chemical abundances and atmospheric properties by 'inverting' the measured spectrum of the atmosphere, and is the only viable path forward for directly studying the chemistry of exoplanets. I will focus on transmission spectra, reviewing the historical developments, summarising the state-of-the-art theory and demonstrating how the transit chord at a given wavelength probes a limited range of pressures and is therefore insensitive to temperature variations. I will discuss in great detail a key limitation of interpreting transmission spectra known as the normalisation degeneracy, examining it in three different regimes of atmospheric retrieval (HST, JWST, ground-based high-resolution). Finally, I will review the work of Fisher & Heng (2018, MNRAS, 481, 4698), who subjected all 38 existing Hubble Space Telescope-WFC3 near-infrared transmission spectra to a Bayesian hierarchy of retrievals. Three case studies out of the 38 will be explicitly discussed: HD 189733b, TRAPPIST-1d and WASP-76b. No correlation is found between the retrieved water abundances and exoplanet mass. I will preview some future work on machine-learning retrieval."


Monday, 25th Feb 2019 [UCLA: Jonathan Mitchell]
09.30–10.00: Driving to UCLA
10.00–11.00: Arrival and meeting Jonathan Mitchell
11.00–12.00: Schlichting group, Geology 4644
12.00–13.00: Helen Parish, Slichter 4855
13.00–14.00: iPLEX lunch seminar, Slichter 3853
14.00–16.00: Mitchell group, Geology 4680
16.00–17.00: Thomas Navarro
Tuesday, 26th Feb 2019 [Carnegie Observatories: Shannon Patel, Tony Piro]
08.30–11.00: Driving to Pasadena + checking into hotel + walking to Carnegie (not available)
11.00–12.00: Tea talk
12.15–13.15: Lunch with postdocs
13.30–14:00: Tony Piro
14.00–14:30: Andy McWilliams
14.30–15:00: Alicia Lanz
15.00–15.30: Alex Ji
15.30–16.00: talk prep
16.00–17.00: Carnegie Observatories Colloquium
Wednesday, 27th Feb 2019 [IPAC-Caltech (Morrisroe 143): Calen Henderson]
09.00–10.00: Heather Knutson, 170 South Mudd
10.00–10.30: Nicole Wallack, 158 South Mudd
10.30–11.00: Shreyas Vissapragada, 160 South Mudd
11.00–12.00: Calen B. Henderson (IPAC)
12.00–13.00: IPAC-Caltech Lunch Seminar: Morrisroe Large Conference Room (MR 102)
13.00–14.00: Lunch with Dawn Gelino, Chas Beichman, Jessie Christiansen
14.00–15.00: Dawn Gelino
15.00–16.00: Yuk Yung, 157 South Mudd
16.00–17.00: Jesse Christensen, Dawn Gelino
Thursday, 28th Feb 2019 [JPL: Renyu Hu]
09.00–10.00: Driving to JPL
10.00–11.00: Greeting and tour of JPL (visitor center, Renyu Hu)
11.00–12.00: JPL Astrophysics Colloquium (Room 169-336)
12.00–13.00: Lunch (Cafeteria, Karl Stapelfeldt, Eric Mamajek)
13.00–13.30: Garreth Ruane (Mall coffee cart)
13.30–14.00: Vanessa Bailey (Mall coffee cart)
14.00–14.30: Meeting with Liton Majumdar (Room 169-530)
14.30–15:30: Meeting with Gracha Rocha
15.30–16.00: Meeting with Keeyoon Sung
16.00–17.00: Meeting with Mario Damiano
Friday, 1st March 2019 [UC-Riverside: Stephen Kane]
08.00–09.00: Telecon with editors of Molecular Astrophysics journal
09.00–10.00: Driving+logistics (not available)
10.00–11.00: Driving+logistics (not available)
11.00–12.00: Stephen Kane
12.00–13.00: Department BBQ lunch
13.00–14.00: Astrobiology Seminar
14.00–15:00: Meeting with Eddie Schwieterman (Room 1278B)
15:00-15:30: Meeting with Teo Mocnik in his office
15.30–16.00: Meeting with Paul Dalba (Room 2460N)