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Simulating the Multi-epoch Direct Detection Technique to Isolate the Thermal Emission of the Non-transiting Hot Jupiter HD187123b

Buzard, Cam and Finnerty, Luke and Piskorz, Danielle and Pelletier, Stefan and Benneke, Björn and Bender, Chad F. and Lockwood, Alexandra C. and Wallack, Nicole L. and Wilkins, Olivia H. and Blake, Geoffrey A. (2020) Simulating the Multi-epoch Direct Detection Technique to Isolate the Thermal Emission of the Non-transiting Hot Jupiter HD187123b. Astronomical Journal, 160 (1). Art. No. 1. ISSN 1538-3881. doi:10.3847/1538-3881/ab8f9c.

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We report the 6.5σ detection of water from the hot Jupiter HD187123b with a Keplerian orbital velocity K_p of 53 ± 13 km s⁻¹. This high-confidence detection is made using a multi-epoch, high-resolution, cross-correlation technique, and corresponds to a planetary mass of 1.4^(+0.5)_(−0.3) M_J and an orbital inclination of 21° ± 5°. The technique works by treating the planet/star system as a spectroscopic binary and obtaining high signal-to-noise, high-resolution observations at multiple points across the planet's orbit to constrain the system's binary dynamical motion. All together, seven epochs of Keck/NIRSPEC L-band observations were obtained, with five before the instrument upgrade and two after. Using high-resolution SCARLET planetary and PHOENIX stellar spectral models, we were able to drastically increase the confidence of the detection by running simulations that could reproduce, and thus remove, the nonrandom structured noise in the final likelihood space well. The ability to predict multi-epoch results will be extremely useful for furthering the technique. Here, we use these simulations to compare three different approaches to combining the cross correlations of high-resolution spectra and find that the Zucker log(L) approach is least affected by unwanted planet/star correlation for our HD187123 data set. Furthermore, we find that the same total signal-to-noise ratio (S/N) spread across an orbit in many, lower S/N epochs rather than fewer, higher S/N epochs could provide a more efficient detection. This work provides a necessary validation of multi-epoch simulations, which can be used to guide future observations and will be key to studying the atmospheres of farther separated, non-transiting exoplanets.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Buzard, Cam0000-0002-9943-6124
Finnerty, Luke0000-0002-1392-0768
Piskorz, Danielle0000-0003-4451-2342
Pelletier, Stefan0000-0002-8573-805X
Benneke, Björn0000-0001-5578-1498
Bender, Chad F.0000-0003-4384-7220
Wallack, Nicole L.0000-0003-0354-0187
Wilkins, Olivia H.0000-0001-7794-7639
Blake, Geoffrey A.0000-0003-0787-1610
Additional Information:© 2020 The American Astronomical Society. Received 2020 February 5; revised 2020 April 16; accepted 2020 May 1; published 2020 June 4. This manuscript benefited from conversations with Heather Knutson and from feedback from the referee, Matteo Brogi. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This work was partially supported by funding from the NASA Exoplanet Research Program (grant NNX16AI14G, G.A. Blake P.I.).
Group:Astronomy Department
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Exoplanet atmospheres ; Radial velocity ; High resolution spectroscopy
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanet atmospheres (487); Radial velocity (1332); High resolution spectroscopy (2096)
Record Number:CaltechAUTHORS:20200608-074701406
Persistent URL:
Official Citation:Cam Buzard et al 2020 AJ 160 1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103737
Deposited By: Tony Diaz
Deposited On:08 Jun 2020 15:41
Last Modified:16 Nov 2021 18:24

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