TY - JOUR
T1 - Warm ice giant GJ 3470b - II. Revised planetary and stellar parameters from optical to near-infrared transit photometry
AU - Biddle, Lauren I.
AU - Pearson, Kyle A.
AU - Crossfield, Ian J.M.
AU - Fulton, Benjamin J.
AU - Ciceri, Simona
AU - Eastman, Jason
AU - Barman, Travis
AU - Mann, Andrew W.
AU - Henry, Gregory W.
AU - Howard, Andrew W.
AU - Williamson, Michael H.
AU - Sinukoff, Evan
AU - Dragomir, Diana
AU - Vican, Laura
AU - Mancini, Luigi
AU - Southworth, John
AU - Greenberg, Adam
AU - Turner, Jake D.
AU - Thompson, Robert
AU - Taylor, Brian W.
AU - Levine, Stephen E.
AU - Webber, Matthew W.
PY - 2014/4
Y1 - 2014/4
N2 - 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 Teff = 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 ± 0.00021BJDTDB, P = 3.336 6487+0.000 0043 -0.000 0033 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 Rp = 3.88 ± 0.32 R⊕ and Mp = 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 H2-dominated atmosphere exhibiting a strong Rayleigh scattering slope.
AB - 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 Teff = 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 ± 0.00021BJDTDB, P = 3.336 6487+0.000 0043 -0.000 0033 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 Rp = 3.88 ± 0.32 R⊕ and Mp = 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 H2-dominated atmosphere exhibiting a strong Rayleigh scattering slope.
KW - Eclipses
KW - Infrared stars
KW - Planets and satellites: atmospheres
KW - Stars: individual: GJ 3470
KW - Techniques: photometric
KW - Techniques: spectroscopic
UR - http://www.scopus.com/inward/record.url?scp=84905662396&partnerID=8YFLogxK
U2 - 10.1093/mnras/stu1199
DO - 10.1093/mnras/stu1199
M3 - Article
AN - SCOPUS:84905662396
SN - 0035-8711
VL - 443
SP - 1810
EP - 1820
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -