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Warm ice giant GJ 3470b - II. Revised planetary and stellar parameters from optical to near-infrared transit photometry

Biddle, Lauren I. and Pearson, Kyle A. and Crossfield, Ian J. M. and Fulton, Benjamin J. and Ciceri, Simona and Eastman, Jason and Barman, Travis and Mann, Andrew W. and Henry, Gregory W. and Howard, Andrew W. and Williamson, Michael H. and Sinukoff, Evan and Dragomir, Diana and Vican, Laura and Mancini, Luigi and Southworth, John and Greenberg, Adam and Turner, Jake D. and Thompson, Robert and Taylor, Brian W. and Levine, Stephen E. and Webber, Matthew W. (2014) Warm ice giant GJ 3470b - II. Revised planetary and stellar parameters from optical to near-infrared transit photometry. Monthly Notices of the Royal Astronomical Society, 443 (2). pp. 1810-1820. ISSN 0035-8711. https://resolver.caltech.edu/CaltechAUTHORS:20170620-101936018

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Abstract

It is important to explore the diversity of characteristics of low-mass, low-density planets to understand the nature and evolution of this class of planets. We present a homogeneous analysis of 12 new and 9 previously published broad-band photometric observations of the Uranus-sized extrasolar planet GJ 3470b, which belongs to the growing sample of sub-Jovian bodies orbiting M dwarfs. The consistency of our analysis explains some of the discrepancies between previously published results and provides updated constraints on the planetary parameters. Our data are also consistent with previous transit observations of this system. The physical properties of the transiting system can only be constrained as well as the host star is characterized, so we provide new spectroscopic measurements of GJ 3470 from 0.33 to 2.42 μm to aid our analysis. We find R* = 0.48 ± 0.04 R⊙, M* = 0.51 ± 0.06 M⊙, and T_(eff) = 3652 ± 50K for GJ 3470, along with a rotation period of 20.70 ± 0.15 d and an R-band amplitude of 0.01 mag, which is small enough that current transit measurements should not be strongly affected by stellar variability. However, to report definitively whether stellar activity has a significant effect on the light curves, this requires future multiwavelength, multi-epoch studies of GJ 3470. We also present the most precise orbital ephemeris for this system: To = 2455983.70472 ± 0.00021BJD_(TDB), P = 3.336 6487^(+0.0000043)_(−0.0000033)  d, and we see no evidence for transit timing variations greater than 1 min. Our reported planet to star radius ratio is 0.076 42 ± 0.000 37. The physical parameters of this planet are R_p = 3.88 ± 0.32 R⊕ and M_p = 13.73 ± 1.61 M⊕. Because of our revised stellar parameters, the planetary radius we present is smaller than previously reported values. We also perform a second analysis of the transmission spectrum of the entire ensemble of transit observations to date, supporting the existence of an H_2-dominated atmosphere exhibiting a strong Rayleigh scattering slope.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/stu1199DOIArticle
https://arxiv.org/abs/1406.6437arXivDiscussion Paper
ORCID:
AuthorORCID
Crossfield, Ian J. M.0000-0002-1835-1891
Fulton, Benjamin J.0000-0003-3504-5316
Eastman, Jason0000-0003-3773-5142
Barman, Travis0000-0002-7129-3002
Mann, Andrew W.0000-0003-3654-1602
Henry, Gregory W.0000-0003-4155-8513
Howard, Andrew W.0000-0001-8638-0320
Sinukoff, Evan0000-0002-5658-0601
Dragomir, Diana0000-0003-2313-467X
Additional Information:© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 June 17. Received 2014 June 11; in original form 2013 October 29. Published: 25 July 2014. We sincerely thank all of the respective TAC committees responsible for allocating time on the facilities used in our study, as well as the telescope day crews. Special thanks to Dr Elizabeth Green for exchanging observing nights at the Kuiper 1.6 m Telescope to acquire a transit and Rob Zellem for insightful discussion. These results made use of Lowell Observatory's Discovery Channel Telescope, supported by Lowell, Discovery Communications, Boston University, the University of Maryland, and the University of Toledo. The LMI was funded by the National Science Foundation through grant AST-1005313. We also gratefully acknowledge the support from the University of Arizona Astronomy Club. The following internet-based resources were used in this paper: the SIMBAD data base operated by CDS, the ArXiv scientific paper preprint service operated by Cornell University and the ADS operated by the Harvard–Smithsonian Center for Astrophysics.
Funders:
Funding AgencyGrant Number
NSFAST-1005313
Subject Keywords:techniques: photometric – techniques: spectroscopic – eclipses – planets and satellites: atmospheres – stars: individual: GJ 3470– infrared stars
Issue or Number:2
Record Number:CaltechAUTHORS:20170620-101936018
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170620-101936018
Official Citation:Lauren I. Biddle, Kyle A. Pearson, Ian J. M. Crossfield, Benjamin J. Fulton, Simona Ciceri, Jason Eastman, Travis Barman, Andrew W. Mann, Gregory W. Henry, Andrew W. Howard, Michael H. Williamson, Evan Sinukoff, Diana Dragomir, Laura Vican, Luigi Mancini, John Southworth, Adam Greenberg, Jake D. Turner, Robert Thompson, Brian W. Taylor, Stephen E. Levine, Matthew W. Webber; Warm ice giant GJ 3470b – II. Revised planetary and stellar parameters from optical to near-infrared transit photometry. Mon Not R Astron Soc 2014; 443 (2): 1810-1820. doi: 10.1093/mnras/stu1199
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78374
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Jun 2017 19:53
Last Modified:14 Oct 2019 21:46

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