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Author Allen, N.H.; Espinoza, N.; Jordan, A.; Lopez-Morales, M.; Apai, D.; Rackham, B.V.; Kirk, J.; Osip, D.J.; Weaver, I.C.; McGruder, C.; Ceballos, K.O.; Reggiani, H.; Brahm, R.; Rodler, F.; Lewis, N.K.; Fraine, J.
Title ACCESS: Tentative Detection of H2O in the Ground-based Optical Transmission Spectrum of the Low-density Hot Saturn HATS-5b Type
Year 2022 Publication Astronomical Journal Abbreviated Journal Astron. J.
Volume 164 Issue 4 Pages 153
Keywords BAYESIAN-INFERENCE; EXOPLANET; SKY; ATMOSPHERES; EFFICIENT; TOOL; CHEMISTRY; ASTROPY
Abstract We present a precise ground-based optical transmission spectrum of the hot Saturn HATS-5b (T (eq) = 1025 K), obtained as part of the ACCESS survey with the IMACS multi-object spectrograph mounted on the Magellan Baade Telescope. Our spectra cover the 0.5-0.9 mu m region and are the product of five individual transits observed between 2014 and 2018. We introduce the usage of additional second-order light in our analyses, which allows us to extract an “extra” transit light curve, improving the overall precision of our combined transit spectrum. We find that the favored atmospheric model for this transmission spectrum is a solar-metallicity atmosphere with subsolar C/O, whose features are dominated by H2O and with a depleted abundance of Na and K. If confirmed, this would point to a “clear” atmosphere at the pressure levels probed by transmission spectroscopy for HATS-5b. Our best-fit atmospheric model predicts a rich near-IR spectrum, which makes this exoplanet an excellent target for future follow-up observations with the James Webb Space Telescope, both to confirm this H2O detection and to superbly constrain the atmosphere's parameters.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6256 ISBN Medium
Area Expedition Conference
Notes WOS:000856537200001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1650
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Author Carone, L.; Molliere, P.; Zhou, YF.; Bouwman, J.; Yan, F.; Baeyens, R.; Apai, D.; Espinoza, N.; Rackham, BV.; Jordan, A.; Angerhausen, D.; Decin, L.; Lendl, M.; Venot, O.; Henning, T.
Title Indications for very high metallicity and absence of methane in the eccentric exo-Saturn WASP-117b Type
Year 2021 Publication Astronomy & Astrophysics Abbreviated Journal Astron. Astrophys.
Volume 646 Issue Pages A168
Keywords methods: observational; planets and satellites: atmospheres
Abstract Aims. We investigate the atmospheric composition of the long-period (P-orb = 10 days) eccentric exo-Saturn WASP-117b. WASP-117b could be similar in atmospheric temperature and chemistry to WASP-107b. In mass and radius, WASP-117b is similar to WASP-39b, which allows a comparative study of these planets.Methods. We analyzed a near-infrared transmission spectrum of WASP-117b taken with the Hubble Space Telescope (HST) WFC3 G141, which was reduced with two independent pipelines. High-resolution measurements were taken with VLT/ESPRESSO in the optical.Results. We report the robust (3 sigma) detection of a water spectral feature. In a 1D atmosphere model with isothermal temperature, uniform cloud deck, and equilibrium chemistry, the Bayesian evidence of a retrieval analysis of the transmission spectrum indicates a preference for a high atmospheric metallicity

[Fe/H] = 2.58(-0.37)(+0.26)

[Fe/H]=2.58-0.37+0.26 and clear skies. The data are also consistent with a lower metallicity composition [Fe/H] < 1.75 and a cloud deck between 10(-2.2) and 10(-5.1) bar, but with weaker Bayesian preference. We retrieve a low CH4 abundance of <10(-4) volume fraction within 1 sigma and <2 x 10(-1) volume fraction within 3<sigma>. We cannot constrain the equilibrium temperature between theoretically imposed limits of 700 and 1000 K. Further observations are needed to confirm quenching of CH4 with K-zz >= 10(8) cm(2) s(-1). We report indications of Na and K in the VLT/ESPRESSO high-resolution spectrum with substantial Bayesian evidence in combination with HST data.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6361 ISBN Medium
Area Expedition Conference
Notes WOS:000624484900001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1353
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Author Kirk, J.; Rackham, B.V.; MacDonald, R.J.; Lopez-Morales, M.; Espinoza, N.; Lendl, M.; Wilson, J.; D.J.; Wheatley, P.J.; Skillen, I.; Apai, D.; Bixel, A.; Gibson, N.P.; Jordan, A.; Lewis, N.K.; Louden, T.; McGruder, C.D.; Nikolov, N.; Rodler, F.; Weaver, I.C.
Title ACCESS and LRG-BEASTS: A Precise New Optical Transmission Spectrum of the Ultrahot Jupiter WASP-103b Type
Year 2021 Publication Astronomical Journal Abbreviated Journal Astron. J.
Volume 162 Issue 1 Pages 34
Keywords GAS-GIANT EXOPLANET; HOT JUPITERS; ATMOSPHERES; TRANSIT; PLANET; EFFICIENT; SPECTROSCOPY; RETRIEVAL; CHEMISTRY; EXPLAIN
Abstract We present a new ground-based optical transmission spectrum of the ultrahot Jupiter WASP-103b (Teq=2484
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6256 ISBN Medium
Area Expedition Conference
Notes WOS:000667942900001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1434
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Author McGruder, C.D.; Lopez-Morales, M.; Espinoza, N.; Rackham, B.V.; Apai, D.; Jordan, A.; Osip, D.J.; Alam, M.K.; Bixel, A.; Fortney, J.J.; Henry, G.W.; Kirk, J.; Lewis, N.K.; Rodler, F.; Weaver, I.C.
Title ACCESS: Confirmation of No Potassium in the Atmosphere of WASP-31b Type
Year 2020 Publication Astronomical Journal Abbreviated Journal Astron. J.
Volume 160 Issue 5 Pages 22 pp
Keywords
Abstract We present a new optical (400-950 nm) transmission spectrum of the hot Jupiter WASP-31b (M = 0.48 M-J; R = 1.54 R-J; P = 3.41 days), obtained by combining four transit observations. These transits were observed with IMACS on the Magellan Baade Telescope at Las Campanas Observatory as part of the ACCESS project. We investigate the presence of clouds/hazes in the upper atmosphere of this planet, as well as the contribution of stellar activity on the observed features. In addition, we search for absorption features of the alkali elements Na i and K i, with particular focus on K i, for which there have been two previously published disagreeing results. Observations with Hubble Space Telescope (HST)/STIS detected K i, whereas ground-based low- and high-resolution observations did not. We use equilibrium and nonequilibrium chemistry retrievals to explore the planetary and stellar parameter space of the system with our optical data combined with existing near-IR observations. Our best-fit model is that with a scattering slope consistent with a Rayleigh slope (alpha = 5(-3.1)(+2.9)), high-altitude clouds at a log cloud top pressure of -3.6(-2.1)(+2.7) bars, and possible muted H2O features. We find that our observations support other ground-based claims of no K I. Clouds are likely why signals like H2O are extremely muted and Na or K cannot be detected. We then juxtapose our Magellan/IMACS transmission spectrum with existing VLT/FORS2, HST/WFC3, HST/STIS, and Spitzer observations to further constrain the optical-to-infrared atmospheric features of the planet. We find that a steeper scattering slope (alpha = 8.3 +/- 1.5) is anchored by STIS wavelengths blueward of 400 nm and only the original STIS observations show significant potassium signal.
Address [McGruder, Chima D.; Lopez-Morales, Mercedes; Alam, Munazza K.; Kirk, James; Weaver, Ian C.] Harvard & Smithsonian, Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA, Email: chima.mcgruder@cfa.harvard.edu
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6256 ISBN Medium
Area Expedition Conference
Notes WOS:000584919200001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1262
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Author McGruder, C.D.; Lopez-Morales, M.; Kirk, J.; Espinoza, N.; Rackham, B.V.; Alam, M.K.; Allen, N.; Nikolov, N.; Weaver, I.C.; Ceballos, K.O.; Osip, D.J.; Apai, D.; Jordan, A.; Fortney, J.J.
Title ACCESS: Confirmation of a Clear Atmosphere for WASP-96b and a Comparison of Light Curve Detrending Techniques Type
Year 2022 Publication Astronomical Journal Abbreviated Journal Astron. J.
Volume 164 Issue 4 Pages 134
Keywords OPTICAL-TRANSMISSION SPECTRUM; CA-II H; RAYLEIGH-SCATTERING; BAYESIAN-INFERENCE; PANCET PROGRAM; K-EMISSION; LRG-BEASTS; EXOPLANET; HUBBLE; MODEL
Abstract One of the strongest Na I features was observed in WASP-96b. To confirm this novel detection, we provide a new 475-825 nm transmission spectrum obtained with Magellan/IMACS, which indeed confirms the presence of a broad sodium absorption feature. We find the same result when reanalyzing the 400-825 nm VLT/FORS2 data. We also utilize synthetic data to test the effectiveness of two common detrending techniques: (1) a Gaussian processes (GP) routine, and (2) common-mode correction followed by polynomial correction (CMC+Poly). We find that both methods poorly reproduce the absolute transit depths but maintain their true spectral shape. This emphasizes the importance of fitting for offsets when combining spectra from different sources or epochs. Additionally, we find that, for our data sets, both methods give consistent results, but CMC+Poly is more accurate and precise. We combine the Magellan/IMACS and VLT/FORS2 spectra with literature 800-1644 nm HST/ WFC3 spectra, yielding a global spectrum from 400 to 1644 nm. We used the PLATON and Exoretrievals retrieval codes to interpret this spectrum, and find that both yield relatively deeper pressures where the atmosphere is optically thick at log-pressures between 1.3(-1.1)(+1.0) and 0.29(-)(2.02)(+1.86) bars, respectively. Exoretrievals finds solar to supersolar Na I and H2O log-mixing ratios of -5.4(-1.9)(+2.0) and -4.5(-2.0)(+2.0), respectively, while PLATON finds an overall metallicity of log(10) (Z/Z(circle dot)) = -0.49(-0.37)(+1.0) dex. Therefore, our findings are in agreement with the literature and support the inference that the terminator of WASP-96b has few aerosols obscuring prominent features in the optical to near-infrared (near-IR) spectrum.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6256 ISBN Medium
Area Expedition Conference
Notes WOS:000852038000001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1649
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Author Weaver, I.C.; Lopez-Morales, M.; Espinoza, N.; Rackham, B.V.; Osip, D.J.; Apai, D.; Jordan, A.; Bixel, A.; Lewis, N.K.; Alam, M.K.; Kirk, J.; McGruder, C.; Rodler, F.; Fienco, J.
Title ACCESS: A Visual to Near-infrared Spectrum of the Hot Jupiter WASP-43b with Evidence of H2O, but No Evidence of Na or K Type
Year 2020 Publication Astronomical Journal Abbreviated Journal Astron. J.
Volume 159 Issue 1 Pages 21 pp
Keywords
Abstract We present a new ground-based visual transmission spectrum of the hot Jupiter WASP-43b, obtained as part of the ACCESS Survey. The spectrum was derived from four transits observed between 2015 and 2018, with combined wavelength coverage between 5300 and 9000 A and an average photometric precision of 708 ppm in 230 A bins. We perform an atmospheric retrieval of our transmission spectrum combined with literature Hubble Space Telescope/WFC3 observations to search for the presence of clouds/hazes as well as Na, K, H alpha, and H2O planetary absorption and stellar spot contamination over a combined spectral range of 5318-16420 A. We do not detect a statistically significant presence of Na i or K i alkali lines, or H alpha in the atmosphere of WASP-43b. We find that the observed transmission spectrum can be best explained by a combination of heterogeneities on the photosphere of the host star and a clear planetary atmosphere with H2O. This model yields a log evidence of 8.26 0.42 higher than a flat (featureless) spectrum. In particular, the observations marginally favor the presence of large, low-contrast spots over the four ACCESS transit epochs with an average covering fraction T = 132 K 132 K. Within the planet's atmosphere, we recover a log H2O volume mixing ratio of -2.78(-1.47)(+1.38), which is consistent with previous H2O abundance determinations for this planet.
Address [Weaver, Ian C.; Lopez-Morales, Mercedes; Alam, Munazza K.; Kirk, James; McGruder, Chima] Harvard & Smithsonian, Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA, Email: iweaver@cfa.harvard.edu
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6256 ISBN Medium
Area Expedition Conference
Notes WOS:000519136000001 Approved
Call Number UAI @ eduardo.moreno @ Serial 1168
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Author Weaver, IC.; Lopez-Morales, M.; Alam, MK.; Espinoza, N.; Rackham, BV.; Goyal, JM.; MacDonald, RJ.; Lewis, NK.; Apai, D.; Bixel, A.; Jordan, A.; Kirk, J.; McGruder, C.; Osip, DJ.
Title ACCESS: An Optical Transmission Spectrum of the High-gravity Hot Jupiter HAT-P-23b Type
Year 2021 Publication Astronomical Journal Abbreviated Journal Astron. J.
Volume 161 Issue 6 Pages 278
Keywords EXOPLANET HD 189733B; HST PANCET PROGRAM; EXTRASOLAR PLANET; CLOUDY ATMOSPHERE; CLEAR ATMOSPHERE; GIANT PLANET; WATER-VAPOR; GAS GIANT; SPECTROSCOPY; HUBBLE
Abstract We present a new ground-based visible transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b, obtained as part of the ACCESS project. We derive the spectrum from five transits observed between 2016 and 2018, with combined wavelength coverage between 5200 angstrom and 9269 angstrom in 200 angstrom bins, and with a median precision of 247 ppm per bin. HAT-P-23b's relatively high surface gravity (g approximate to 30 m s(-2)), combined with updated stellar and planetary parameters from Gaia DR2, gives a five-scale-height signal of 384 ppm for a hydrogen-dominated atmosphere. Bayesian models favor a clear atmosphere for the planet with the tentative presence of TiO, after simultaneously modeling stellar contamination, using spots parameter constraints from photometry. If confirmed, HAT-P-23b would be the first example of a high-gravity gas giant with a clear atmosphere observed in transmission at optical/near-IR wavelengths; therefore, we recommend expanding observations to the UV and IR to confirm our results and further characterize this planet. This result demonstrates how combining transmission spectroscopy of exoplanet atmospheres with long-term photometric monitoring of the host stars can help disentangle the exoplanet and stellar activity signals.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6256 ISBN Medium
Area Expedition Conference
Notes WOS:000655343200001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1396
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Author Yan, F.; Espinoza, N.; Molaverdikhani, K.; Henning, T.; Mancini, L.; Mallonn, M.; Rackham, B.V.; Apai, D.; Jordan, A.; Molliere, P.; Chen, G.; Carone, L.; Reiners, A.
Title LBT transmission spectroscopy of HAT-P-12b: Confirmation of a cloudy atmosphere with no significant alkali features Type
Year 2020 Publication Astronomy & Astrophysics Abbreviated Journal Astron. Astrophys.
Volume 642 Issue Pages 13 pp
Keywords planets and satellites: atmospheres; techniques: spectroscopic; stars: atmospheres; planets and satellites: individual: HAT-P-12b
Abstract The hot sub-Saturn-mass exoplanet HAT-P-12b is an ideal target for transmission spectroscopy because of its inflated radius. We observed one transit of the planet with the multi-object double spectrograph (MODS) on the Large Binocular Telescope (LBT) with the binocular mode and obtained an atmosphere transmission spectrum with a wavelength coverage of similar to 0.4-0.9 μm. The spectrum is relatively flat and does not show any significant sodium or potassium absorption features. Our result is consistent with the revised Hubble Space Telescope (HST) transmission spectrum of a previous work, except that the HST result indicates a tentative detection of potassium. The potassium discrepancy could be the result of statistical fluctuation of the HST dataset. We fit the planetary transmission spectrum with an extensive grid of cloudy models and confirm the presence of high-altitude clouds in the planetary atmosphere. The fit was performed on the combined LBT and HST spectrum, which has an overall wavelength range of 0.4-1.6 μm. The LBT/MODS spectrograph has unique advantages in transmission spectroscopy observations because it can cover a wide wavelength range with a single exposure and acquire two sets of independent spectra simultaneously.
Address [Yan, F.; Reiners, A.] Georg August Univ, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany, Email: fei.yan@uni-goettingen.de
Corporate Author Thesis
Publisher Edp Sciences S A Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1432-0746 ISBN Medium
Area Expedition Conference
Notes WOS:000581918600001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1237
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