HAT-P-20b-HAT-P-23b: Four massive transiting extrasolar planets

A. G. Bakos, J. Hartman, G. Torres, D. W. Latham, Géza Kovcs, R. W. Noyes, D. A. Fischer, J. A. Johnson, G. W. Marcy, A. W. Howard, D. Kipping, G. A. Esquerdo, A. Shporer, B. Béky, L. A. Buchhave, G. Perumpilly, M. Everett, D. D. Sasselov, R. P. Stefanik, J. LázárI. Papp, P. Sári

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Abstract

We report the discovery of four relatively massive (2-7 M J) transiting extrasolar planets. HAT-P-20b orbits the moderately bright V = 11.339 K3 dwarf star GSC 1910-00239 on a circular orbit, with a period P = 2.875317 ± 0.000004days, transit epoch Tc = 2455080.92661± 0.00021 (BJDUTC), and transit duration 0.0770 0.0008days. The host star has a mass of 0.76 ±0.03 M , radius of 0.69± 0.02 R , effective temperature 4595 ±80K, and metallicity [Fe/H] = +0.35 0.08. The planetary companion has a mass of 7.246± 0.187M J and a radius of 0.867 ±0.033R J yielding a mean density of 13.78± 1.50g cm-3. HAT-P-21b orbits the V = 11.685 G3 dwarf star GSC 3013-01229 on an eccentric (e = 0.228± 0.016) orbit, with a period P = 4.124481± 0.000007days, transit epoch Tc = 2454996.41312± 0.00069, and transit duration 0.1530± 0.0027days. The host star has a mass of 0.95 ±0.04 M , radius of 1.10 0.08 R , effective temperature 5588 80K, and metallicity [Fe/H] = +0.01 0.08. The planetary companion has a mass of 4.063± 0.161M J and a radius of 1.024± 0.092R J yielding a mean density of 4.68 +1.59 - 0.99g cm-3. HAT-P-21b is a borderline object between the pM and pL class planets, and the transits occur near apastron. HAT-P-22b orbits the bright V = 9.732 G5 dwarf star HD 233731 on a circular orbit, with a period P = 3.212220 ±0.000009days, transit epoch Tc = 2454930.22001 ±0.00025, and transit duration 0.1196 0.0014days. The host star has a mass of 0.92 0.03 M , radius of 1.04 0.04 R , effective temperature 5302 80K, and metallicity [Fe/H] = +0.24± 0.08. The planet has a mass of 2.147 0.061M J and a compact radius of 1.080 0.058R J yielding a mean density of 2.11+0.40 - 0.29g cm-3. The host star also harbors an M-dwarf companion at a wide separation. Finally, HAT-P-23b orbits the V = 12.432 G0 dwarf star GSC 1632-01396 on a close to circular orbit, with a period P = 1.212884± 0.000002days, transit epoch Tc = 2454852.26464 ± 0.00018, and transit duration 0.0908 ±0.0007days. The host star has a mass of 1.13 ±0.04 M , radius of 1.20 ±0.07 R , effective temperature 5905± 80K, and metallicity [Fe/H] = +0.15± 0.04. The planetary companion has a mass of 2.090 0.111M J and a radius of 1.368± 0.090R J yielding a mean density of 1.01 ±0.18g cm-3. HAT-P-23b is an inflated and massive hot Jupiter on a very short period orbit, and has one of the shortest characteristic infall times (7.5+2.9 - 1.8Myr) before it gets engulfed by the star.

Original languageEnglish (US)
Article number116
JournalAstrophysical Journal
Volume742
Issue number2
DOIs
StatePublished - Dec 1 2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • stars: individual (HAT-P-20, HAT-P-21, HAT-P-22, HAT-P-23)
  • techniques: photometric
  • techniques: spectroscopic

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    Bakos, A. G., Hartman, J., Torres, G., Latham, D. W., Kovcs, G., Noyes, R. W., Fischer, D. A., Johnson, J. A., Marcy, G. W., Howard, A. W., Kipping, D., Esquerdo, G. A., Shporer, A., Béky, B., Buchhave, L. A., Perumpilly, G., Everett, M., Sasselov, D. D., Stefanik, R. P., ... Sári, P. (2011). HAT-P-20b-HAT-P-23b: Four massive transiting extrasolar planets. Astrophysical Journal, 742(2), [116]. https://doi.org/10.1088/0004-637X/742/2/116