Published October 1, 2007 | Version Published
Journal Article Open

TrES-4: A Transiting Hot Jupiter of Very Low Density

  • 1. ROR icon Lowell Observatory
  • 2. ROR icon California Institute of Technology
  • 3. ROR icon Harvard-Smithsonian Center for Astrophysics
  • 4. ROR icon Osservatorio Astrofisico di Torino
  • 5. ROR icon Planetary Science Institute
  • 6. ROR icon Las Cumbres Observatory Global Telescope Network
  • 7. ROR icon University of California, Santa Barbara
  • 8. ROR icon Instituto de Astrofísica de Canarias

Abstract

We report the discovery of TrES-4, a hot Jupiter that transits the star GSC 02620-00648 every 3.55 days. From high-resolution spectroscopy of the star, we estimate a stellar effective temperature of T_(eff) = 6100 ± 150 K, and from high-precision z and B photometry of the transit we constrain the ratio of the semimajor axis a and the stellar radius R_* to be a/R_* = 6.03 ± 0.13. We compare these values to model stellar isochrones to constrain the stellar mass to be M_* = 1.22 ± 0.17 M_⊙. Based on this estimate and the photometric time series, we constrain the stellar radius to be R_* = 1.738 ± 0.092 R_⊙ and the planet radius to be R_p = 1.674 ± 0.094 R_(Jup). We model our radial velocity data assuming a circular orbit and find a planetary mass of 0.84 ± 0.10 M_(Jup). Our radial velocity observations rule out line-bisector variations that would indicate a specious detection resulting from a blend of an eclipsing binary system. TrES-4 has the largest radius and lowest density of any of the known transiting planets. It presents a challenge to current models of the physical structure of hot Jupiters and indicates that the diversity of physical properties among the members of this class of exoplanets has yet to be fully explored.

Additional Information

© 2007 The American Astronomical Society. Received 2007 June 18; accepted 2007 August 6; published 2007 September 14. We thank Travis Barman for useful discussions. This Letter is based on work supported in part by NASA grants NNG04GN74G, NNG04LG89G, NNG05GI57G, NNG05GJ29G, and NNH05AB88I through the Origins of Solar Systems Program, and NASA Planetary Major Equipment grant N4G5-12229.We acknowledge support from the NASA Kepler mission under cooperative agreement NCC2-1390. Work by G. A´. B. was supported by NASA through Hubble Fellowship grant HST-HF-01170.01-A. Observing time on Keck I was awarded by NASA.

Attached Files

Published - MANapjl07.pdf

Files

MANapjl07.pdf

Files (86.1 kB)

Name Size
md5:a29e23576f4140f9ba9a9a71ceee9e09
86.1 kB Preview Download

Additional details

Identifiers

Eprint ID
17395
Resolver ID
CaltechAUTHORS:20100205-095420946

Funding

NASA
NNG04GN74G
NASA
NNG04LG89G
NASA
NNG05GI57G
NASA
NNG05GJ29G
NASA
NNH05AB88I
NASA Planetary Major Equipment
N4G5-12229
NASA Kepler mission
NCC2-1390
NASA Hubble Fellowship
HST-HF-01170.01-A

Dates

Created
2010-02-09
Created from EPrint's datestamp field
Updated
2021-11-08
Created from EPrint's last_modified field