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G. Á. Bakos,
G. Torres,
A. Pál,
J. Hartman,
Géza Kovács,
R. W. Noyes,
D. W. Latham,
D. D. Sasselov,
B. Sipőcz,
G. A. Esquerdo, [......],
H. Isaacson,
A. Howard,
S. Vogt, Gábor Kovács,
J. Fernandez,
A. Moór,
R. P. Stefanik,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report on the discovery of HAT-P-11b, the smallest radius transiting extrasolar planet (TEP) discovered from the ground, and the first hot Neptune discovered to date by transit searches. HAT-P-11b orbits the bright (V = 9.587) and metal rich ([Fe/H] = +0.31 ± 0.05) K4 dwarf star GSC 03561-02092 with P = 4.8878162 ± 0.0000071 days and produces a transit signal with depth of 4.2 mmag, the shallowest found by transit searches that is due to a confirmed planet. We present a global analysis of the available photometric and radial velocity (RV) data that result in stellar and planetary parameters, with simultaneous treatment of systematic variations. The planet, like its near-twin GJ 436b, is somewhat larger than Neptune (17 M ⊕, 3.8 R ⊕) both in mass Mp = 0.081 ± 0.009 M J(25.8 ± 2.9 M ⊕) and radius Rp = 0.422 ± 0.014 R J(4.73 ± 0.16 R ⊕). HAT-P-11b orbits in an eccentric orbit with e = 0.198 ± 0.046 and ω = 3552 ± 173, causing a reflex motion of its parent star with amplitude 11.6 ± 1.2 m s–1, a challenging detection due to the high level of chromospheric activity of the parent star. Our ephemeris for the transit events is Tc = 2454605.89132 ± 0.00032 (BJD), with duration 0.0957 ± 0.0012 days, and secondary eclipse epoch of 2454608.96 ± 0.15 days (BJD). The basic stellar parameters of the host star are M = 0.809+0.020 –0.027 M ☉, R = 0.752 ± 0.021 R ☉, and T eff = 4780 ± 50 K. Importantly, HAT-P-11 will lie on one of the detectors of the forthcoming Kepler mission; this should make possible fruitful investigations of the detailed physical characteristic of both the planet and its parent star at unprecedented precision. We discuss an interesting constraint on the eccentricity of the system by the transit light curve and stellar parameters. This will be particularly useful for eccentric TEPs with low-amplitude RV variations in Kepler's field. We also present a blend analysis, that for the first time treats the case of a blended transiting hot Jupiter mimicking a transiting hot Neptune, and proves that HAT-P-11b is not such a blend.
The Astrophysical Journal 02/2010; 710(2):1724. · 6.02 Impact Factor
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G. Á. Bakos,
A. W. Howard,
R. W. Noyes,
J. Hartman,
G. Torres,
Géza Kovács,
D. A. Fischer,
D. W. Latham,
J. A. Johnson,
G. W. Marcy,
D. D. Sasselov,
R. P. Stefanik,
B. Sipőcz, Gábor Kovács,
G. A. Esquerdo,
A. Pál,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report on the discovery of a planetary system with a close-in transiting hot Jupiter on a near circular orbit and a massive outer planet on a highly eccentric orbit. The inner planet, HAT-P-13b, transits the bright V = 10.622 G4 dwarf star GSC 3416 – 00543 every P = 2.916260 ± 0.000010 days, with transit epoch Tc = 2454779.92979 ± 0.00038 (BJD) and duration 0.1345 ± 0.0017 days. The outer planet HAT-P-13c orbits the star every P 2 = 428.5 ± 3.0 days with a nominal transit center (assuming zero impact parameter) of T 2c = 2454870.4 ± 1.8 (BJD) or time of periastron passage T 2,peri = 2454890.05 ± 0.48 (BJD). Transits of the outer planet have not been observed, and may not be present. The host star has a mass of 1.22+0.05 –0.10 M ☉, radius of 1.56 ± 0.08 R ☉, effective temperature of 5653 ± 90 K, and is rather metal-rich with [Fe/H] = +0.41 ± 0.08. The inner planetary companion has a mass of 0.853+0.029 –0.046 M J, and radius of 1.281 ± 0.079 R J, yielding a mean density of 0.498+0.103 –0.069 g cm–3. The outer companion has m 2sin i 2 = 15.2 ± 1.0 M J, and orbits on a highly eccentric orbit of e 2 = 0.691 ± 0.018. While we have not detected significant transit timing variations of HAT-P-13b, due to gravitational and light-travel time effects, future observations will constrain the orbital inclination of HAT-P-13c, along with its mutual inclination to HAT-P-13b. The HAT-P-13 (b, c) double-planet system may prove extremely valuable for theoretical studies of the formation and dynamics of planetary systems.
The Astrophysical Journal 11/2009; 707(1):446. · 6.02 Impact Factor
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J. D. Hartman,
G. Á. Bakos,
G. Torres,
Géza Kovács,
R. W. Noyes,
A. Pál,
D. W. Latham,
B. Sipőcz,
D. A. Fischer,
J. A. Johnson, [......],
R. P. Butler,
A. W. Howard,
G. A. Esquerdo,
D. D. Sasselov, Gábor Kovács,
R. P. Stefanik,
J. M. Fernandez,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report on the discovery of HAT-P-12b, a transiting extrasolar planet orbiting the moderately bright V 12.8 K4 dwarf GSC 03033 – 00706, with a period P = 3.2130598 ± 0.0000021 d, transit epoch Tc = 2454419.19556 ± 0.00020 (BJD), and transit duration 0.0974 ± 0.0006 d. The host star has a mass of 0.73 ± 0.02 M ☉, radius of 0.70+0.02 –0.01 R ☉, effective temperature 4650 ± 60 K, and metallicity [Fe/H] = –0.29 ± 0.05. We find a slight correlation between the observed spectral line bisector spans and the radial velocity, so we consider, and rule out, various blend configurations including a blend with a background eclipsing binary, and hierarchical triple systems where the eclipsing body is a star or a planet. We conclude that a model consisting of a single star with a transiting planet best fits the observations, and show that a likely explanation for the apparent correlation is contamination from scattered moonlight. Based on this model, the planetary companion has a mass of 0.211 ± 0.012 M J and radius of 0.959+0.029 –0.021 R J yielding a mean density of 0.295 ± 0.025 g cm–3. Comparing these observations with recent theoretical models, we find that HAT-P-12b is consistent with a ~1-4.5 Gyr, mildly irradiated, H/He-dominated planet with a core mass MC 10 M ⊕. HAT-P-12b is thus the least massive H/He-dominated gas giant planet found to date. This record was previously held by Saturn.
The Astrophysical Journal 11/2009; 706(1):785. · 6.02 Impact Factor
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G. Á. Bakos,
A. Pál,
G. Torres,
B. Sipőcz,
D. W. Latham,
R. W. Noyes,
Géza Kovács,
J. Hartman,
G. A. Esquerdo,
D. A. Fischer,
J. A. Johnson,
G. W. Marcy,
R. P. Butler,
A. W. Howard,
D. D. Sasselov, Gábor Kovács,
R. P. Stefanik,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report on the discovery of HAT-P-10b, one of the lowest mass (0.487 ± 0.018 M J) transiting extrasolar planets (TEPs) discovered to date by transit searches. HAT-P-10b orbits the moderately bright V = 11.89 K dwarf GSC 02340-01714, with a period P = 3.7224747 ± 0.0000065 days, transit epoch Tc = 2454759.68683 ± 0.00016 (BJD), and duration 0.1090 ± 0.0008 days. HAT-P-10b has a radius of 1.005+0.032 –0.027 R J yielding a mean density of 0.594 ± 0.052 g cm–3. Comparing these observations with recent theoretical models we find that HAT-P-10b is consistent with a ~4.5 Gyr, almost pure hydrogen and helium gas giant planet with a 10 M ⊕ core. With an equilibrium temperature of T eq = 1020 ± 17 K, HAT-P-10b is one of the coldest TEPs. Curiously, its Safronov number θ = 0.053 ± 0.002 falls close to the dividing line between the two suggested TEP populations.
The Astrophysical Journal 04/2009; 696(2):1950. · 6.02 Impact Factor
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A. Pál,
G. Á. Bakos,
G. Torres,
R. W. Noyes,
D. W. Latham,
Géza Kovács,
G. W. Marcy,
D. A. Fischer,
R. P. Butler,
D. D. Sasselov,
B. Sipőcz,
G. A. Esquerdo, Gábor Kovács,
R. Stefanik,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report on the latest discovery of the HATNet project: a very hot giant planet orbiting a bright (V = 10.5) star with a small semimajor axis of a = 0.0377 ± 0.0005 AU. Ephemeris for the system is P = 2.2047299 ± 0.0000040 days, midtransit time E = 2,453,790.2593 ± 0.0010 (BJD). Based on the available spectroscopic data on the host star and photometry of the system, the planet has a mass of Mp = 1.78+ 0.08−0.05 MJ and radius of Rp = 1.36+ 0.20−0.09 RJ. The parent star is a slightly evolved F6 star with M = 1.47+ 0.08−0.05 M☉, R = 1.84+ 0.23−0.11 R☉, Teff = 6350 ± 80 K, and metallicity [ Fe/H ] = + 0.26 ± 0.08. The relatively hot and large host star, combined with the close orbit of the planet, yield a very high planetary irradiance of 4.71+ 1.44−0.05 × 109 erg cm−2 s−1, which places the planet near the top of the pM class of irradiated planets as defined by Fortney et al. If as predicted by Fortney et al. the planet reradiates its absorbed energy before distributing it to the night side, the day-side temperature should be about 2730+ 150−100 K. Because the host star is quite bright, measurement of the secondary eclipse should be feasible for ground-based telescopes, providing a good opportunity to compare the predictions of current hot Jupiter atmospheric models with the observations. Moreover, the host star falls in the field of the upcoming Kepler mission; hence extensive space-borne follow-up, including not only primary transit and secondary eclipse observations but also asteroseismology, will be possible.
The Astrophysical Journal 12/2008; 680(2):1450. · 6.02 Impact Factor
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R. W. Noyes,
G. Á. Bakos,
G. Torres,
A. Pál,
Géza Kovács,
D. W. Latham,
J. M. Fernández,
D. A. Fischer,
R. P. Butler,
G. W. Marcy,
B. Sipőcz,
G. A. Esquerdo, Gábor Kovács,
D. D. Sasselov,
B. Sato,
R. Stefanik,
M. Holman,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: In the ongoing HATNet survey we have detected a giant planet, with radius 1.33 ± 0.06 RJup and mass 1.06 ± 0.12 MJup, transiting the bright (V = 10.5) star GSC 03239–00992. The planet is in a circular orbit with period 3.852985 ± 0.000005 days and midtransit epoch 2,454,035.67575 ± 0.00028 (HJD). The parent star is a late F star with mass 1.29 ± 0.06 M☉, radius 1.46 ± 0.06 R☉, Teff ~ 6570 ± 80 K , [ Fe/H ] = − 0.13 ± 0.08, and age ~2.3+ 0.5−0.7 Gyr. With this radius and mass, HAT-P-6b has somewhat larger radius than theoretically expected. We describe the observations and their analysis to determine physical properties of the HAT-P-6 system, and briefly discuss some implications of this finding.
The Astrophysical Journal 12/2008; 673(1):L79. · 6.02 Impact Factor
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G. Bakos,
C. Afonso,
T. Henning,
A. Jordán,
M. Holman,
R. W. Noyes,
P. D. Sackett,
D. Sasselov, Gábor Kovács,
Z. Csubry,
A. Pál
[show abstract]
[hide abstract]
ABSTRACT: HAT-South is a network of six identical, fully automated wide field telescopes, to be located at three sites (Chile: Las Campanas, Australia: Siding Springs, and Namibia: HESS site) in the Southern hemisphere. The primary purpose of the network is to detect and characterize a large number of extra-solar planets transiting nearby bright stars, and to explore their diversity. Operation of HAT-South is a collaboration among the Harvard-Smithsonian Center for Astrophysics (CfA), Max Planck Institute for Astronomy (MPIA) and the Australian National University (ANU). The network is expected to be ready for initial science operations in 2009. The three sites will permit near round-the-clock monitoring of selected fields, and the continuous data-stream will greatly enhance recovery of transits. HAT-South will be sensitive to planetary transits down to Rââ°Ë14 across a 128 square-degrees combined field of view, thereby targeting a large number of dwarfs with feasible confirmation-mode follow-up. We anticipate a yearly detection rate of approximately 25 planets transiting bright stars.
Pont, Frédéric; Sasselov, Dimitar; Holman, Matthews: Transiting Planets, Cambridge Univ. Press, 354-357 (2009).
