HAT-P-4b: A metal-rich low-density transiting hot Jupiter

G. Kovács, G. Á Bakos, G. Torres, A. Sozzetti, D. W. Latham, R. W. Noyes, R. P. Butler, G. W. Marcy, D. A. Fischer, J. M. Fernández, G. Esquerdo, D. D. Sasselov, R. P. Stefanik, A. Pál, J. Lázár, I. Papp, P. Sári

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


We describe the discovery of HAT-P-4b, a low-density extrasolar planet transiting BD +36 2593, a V = 11.2 mag slightly evolved metal-rich late F star. The planet's orbital period is 3.056536 ± 0.000057 days with a midtransit epoch of 2,454,245.8154 ± 0.0003 (HJD). Based on high-precision photometric and spectroscopic data, and by using transit light curve modeling, spectrum analysis, and evolutionary models, we derive the following planet parameters: Mp = 0.68 ± 0.04 MRJ, R p = 1.27 ± 0.05 RJ ρp = 0.41 ± 0.06 g cm-3, and a = 0.0446 ± 0.0012 AU. Because of its relatively large radius, together with its assumed high metallicity (that of its parent star), this planet adds to the theoretical challenges of explaining inflated extrasolar planets.

Original languageEnglish (US)
Pages (from-to)L41-L44
JournalAstrophysical Journal
Issue number1 PART 2
StatePublished - 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planetary systems
  • Techniques: photometric
  • Techniques: spectroscopic


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