-
M. Mohler-Fischer,
L. Mancini, J. D. Hartman,
G. B. Bakos,
K. Penev,
D. Bayliss,
A. Jordan,
Z. Csubry,
G. Zhou,
M. Rabus, [......],
T. Henning,
D. J. Wright,
C. G. Tinney,
B. C. Addison,
B. Schmidt,
R. W. Noyes,
I. Papp,
J. Lazar,
P. Sari,
P. Conroy
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of HATS-2b, the second transiting extrasolar planet
detected by the HATSouth survey. HATS-2b is moving on a circular orbit around a
V=13.6 mag, K-type dwarf star (GSC 6665-00236), at a separation of 0.0230 \pm
0.0003 AU and with a period of 1.3541 days. The planetary parameters have been
robustly determined using a simultaneous fit of the HATSouth,
MPG/ESO~2.2\,m/GROND, Faulkes Telescope South/Spectral transit photometry and
MPG/ESO~2.2\,m/FEROS, Euler~1.2\,m/CORALIE, AAT~3.9\,m/CYCLOPS radial-velocity
measurements. HATS-2b has a mass of 1.37 \pm 0.16 M_J, a radius of 1.14 \pm
0.03 R_J and an equilibrium temperature of 1567 \pm 30 K. The host star has a
mass of 0.88 \pm 0.04 M_Sun, radius of 0.89 \pm 0.02 R_Sun and shows starspot
activity. We characterized the stellar activity by analysing two photometric
follow-up transit light curves taken with the GROND instrument, both obtained
simultaneously in four optical bands (covering the wavelength range of
3860-9520 \AA). The two light curves contain anomalies compatible with
starspots on the photosphere of the parent star along the same transit chord.
04/2013;
-
K. Penev,
G. Á. Bakos,
D. Bayliss,
A. Jordán,
M. Mohler,
G. Zhou,
V. Suc,
M. Rabus, J. D. Hartman,
L. Mancini, [......],
P. Conroy,
R. W. Noyes,
D. D. Sasselov,
B. Schmidt,
D. J. Wright,
C. G. Tinney,
B. C. Addison,
J. Lázár,
I. Papp,
P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of HATS-1b, a transiting extrasolar planet orbiting
the moderately bright V=12.05 G dwarf star GSC 6652-00186, and the first planet
discovered by HATSouth, a global network of autonomous wide-field telescopes.
HATS-1b has a period P~3.4465 d, mass Mp~1.86MJ, and radius Rp~1.30RJ. The host
star has a mass of 0.99Msun, and radius of 1.04Rsun. The discovery light curve
of HATS-1b has near continuous coverage over several multi-day periods,
demonstrating the power of using a global network of telescopes to discover
transiting planets.
06/2012;
-
G. Á. Bakos,
Z. Csubry,
K. Penev,
D. Bayliss,
A. Jordán,
C. Afonso, J. D. Hartman,
T. Henning,
G. Kovács,
R. W. Noyes, [......],
J. Lázár,
I. Papp,
P. Sári,
P. Conroy,
G. Zhou,
P. D. Sackett,
B. Schmidt,
L. Mancini,
D. D. Sasselov,
K. Ueltzhoeffer
[show abstract]
[hide abstract]
ABSTRACT: HATSouth is the world's first network of automated and homogeneous telescopes
that is capable of year-round 24-hour monitoring of positions over an entire
hemisphere of the sky. The primary scientific goal of the network is to
discover and characterize a large number of transiting extrasolar planets,
reaching out to long periods and down to small planetary radii. HATSouth
achieves this by monitoring extended areas on the sky, deriving high precision
light curves for a large number of stars, searching for the signature of
planetary transits, and confirming planetary candidates with larger telescopes.
HATSouth employs 6 telescope units spread over 3 locations with large longitude
separation in the southern hemisphere (Las Campanas Observatory, Chile; HESS
site, Namibia; Siding Spring Observatory, Australia). Each of the HATSouth
units holds four 0.18m diameter f/2.8 focal ratio telescope tubes on a common
mount producing an 8.2x8.2 arcdeg field, imaged using four 4Kx4K CCD cameras
and Sloan r filters, to give a pixel scale of 3.7 arcsec/pixel. The HATSouth
network is capable of continuously monitoring 128 square arc-degrees. We
present the technical details of the network, summarize operations, and present
weather statistics for the 3 sites. On average each of the 6 HATSouth units has
conducted observations on ~500 nights over a 2-year time period, yielding a
total of more than 1million science frames at 4 minute integration time, and
observing ~10.65 hours per day on average. We describe the scheme of our data
transfer and reduction from raw pixel images to trend-filtered light curves and
transiting planet candidates. Photometric precision reaches ~6 mmag at 4-minute
cadence for the brightest non-saturated stars at r~10.5. We present detailed
transit recovery simulations to determine the expected yield of transiting
planets from HATSouth. (abridged)
06/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: HD 15082 (WASP-33) is the hottest and fastest rotating star known to harbor a
transiting extrasolar planet (WASP-33b). The lack of high precision radial
velocity (RV) data stresses the need for precise light curve analysis and
gathering further RV data. By using available photometric and RV data, we
perform a blend analysis, compute more accurate system parameters, confine the
planetary mass and attempt to cast light on the observed transit anomalies. We
combine the original HATNet observations and various followup data to jointly
analyze the signal content and extract the transit component and use our RV
data to aid the global parameter determination. The blend analysis of the
combination of multicolor light curves yields the first independent
confirmation of the planetary nature of WASP-33b. We clearly identify three
frequency components in the 15-21 1/day regime with amplitudes 7-5 mmag. These
frequencies correspond to the delta Scuti-type pulsation of the host star. None
of these pulsation frequencies or their low-order linear combinations are in
close resonance with the orbital frequency. We show that these pulsation
components explain some but not all of the observed transit anomalies. The
grand-averaged transit light curve shows that there is a ~1.5 mmag brightening
shortly after the planet passes the mid-transit phase. Although the duration
and amplitude of this brightening varies, it is visible even through the direct
inspections of the individual transit events (some 40-60% of the followup light
curves show this phenomenon). We suggest that the most likely explanation of
this feature is the presence of a well-populated spot belt which is highly
inclined to the orbital plane. This geometry is consistent with the inference
from the spectroscopic anomalies. Finally, we constrain the planetary mass to
M_p=3.27+/-0.73 M_J by using our RV data collected by the TRES spectrograph.
05/2012;
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B. Sato, J. D. Hartman,
G. Á. Bakos,
B. Béky,
G. Torres,
D. W. Latham,
G. Kovács,
Z. Csubry,
K. Penev,
R. W. Noyes, [......],
G. A. Esquerdo,
D. A. Fischer,
A. W. Howard,
J. A. Johnson,
G. W. Marcy,
D. D. Sasselov,
T. Szklenár,
J. Lázár,
I. Papp,
P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of HAT-P-38b, a Saturn-mass exoplanet transiting the
V=12.56 dwarf star GSC 2314-00559 on a P = 4.6404 d circular orbit. The host
star is a 0.89Msun late G-dwarf, with solar metallicity, and a radius of
0.92Rsun. The planetary companion has a mass of 0.27MJ, and radius of 0.82RJ.
HAT-P-38b is one of the closest planets in mass and radius to Saturn ever
discovered.
01/2012;
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G. Á. Bakos, J. D. Hartman,
G. Torres,
B. Béky,
D. W. Latham,
L. A. Buchhave,
Z. Csubry,
G. Kovács,
A. Bieryla,
S. Quinn, [......],
G. W. Marcy,
B. Sato,
K. Penev,
M. Everett,
D. D. Sasselov,
G. Fürész,
R. P. Stefanik,
J. Lázár,
I. Papp,
P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of four transiting extrasolar planets (HAT-P-34b -
HAT-P-37b) with masses ranging from 1.05 to 3.33 MJ and periods from 1.33 to
5.45 days. These planets orbit relatively bright F and G dwarf stars (from V =
10.16 to V = 13.2). Of particular interest is HAT-P-34b which is moderately
massive (3.33 MJ), has a high eccentricity of e = 0.441 +/- 0.032 at P =
5.4526540+/-0.000016 d period, and shows hints of an outer component. The other
three planets have properties that are typical of hot Jupiters.
01/2012;
-
K. A. Alsubai,
N. R. Parley,
D. M. Bramich,
R. G. West,
P. M. Sorensen,
A. Collier Cameron,
D. W. Latham,
K. Horne,
D. R. Anderson,
G. Á. Bakos, [......],
M. E. Everett,
G. Fűrész, J. D. Hartman,
C. Hellier,
G. M. Miller,
D. Pollacco,
S. N. Quinn,
J. C. Smith,
R. P. Stefanik,
A. Szentgyorgyi
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery and initial characterization of Qatar-1b, a hot Jupiter-orbiting metal-rich K dwarf star, the first planet discovered by the Qatar Exoplanet Survey. We describe the strategy used to select candidate transiting planets from photometry generated by the Qatar Exoplanet Survey camera array. We examine the rate of astrophysical and other false positives found during the spectroscopic reconnaissance of the initial batch of candidates. A simultaneous fit to the follow-up radial velocities and photometry of Qatar-1b yields a planetary mass of 1.09 ± 0.08 MJ and a radius of 1.16 ± 0.05 RJ. The orbital period and separation are 1.420 033 ± 0.000 016 d and 0.023 43 ± 0.000 26 au for an orbit assumed to be circular. The stellar density, effective temperature and rotation rate indicate an age greater than 4 Gyr for the system.
Monthly Notices of the Royal Astronomical Society 10/2011; 417(1):709 - 716. · 4.90 Impact Factor
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J. D. Hartman,
G. Á. Bakos,
G. Torres,
D. W. Latham,
G. Kovács,
B. Béky,
S. N. Quinn,
T. Mazeh,
A. Shporer,
G. W. Marcy, [......],
J A Johnson,
G. A. Esquerdo,
R. W. Noyes,
D. D. Sasselov,
R. P. Stefanik,
J. M. Fernandez,
T. Szklenár,
J. Lázár,
I. Papp,
P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of two exoplanets transiting high-jitter stars.
HAT-P-32b orbits the bright V=11.289 star GSC 3281-00800, with a period P =
2.150008 d. The stellar and planetary masses and radii depend on the
eccentricity of the system, which is poorly constrained due to the high
velocity jitter (~80m/s). Assuming a circular orbit, the star has a mass of
1.16+-0.04 M_sun, and radius of 1.22+-0.02 R_sun, while the planet has a mass
of 0.860+-0.164 MJ, and a radius of 1.789+-0.025 RJ. When the eccentricity is
allowed to vary, the best-fit model results in a planet which is close to
filling its Roche Lobe. Including the constraint that the planet cannot exceed
its Roche Lobe results in the following best-fit parameters: e = 0.163+-0.061,
Mp = 0.94+-0.17 MJ, Rp = 2.04+-0.10 RJ, Ms = 1.18+0.04-0.07 M_sun and Rs =
1.39+-0.07 R_sun. The second planet, HAT-P-33b, orbits the bright V=11.188 star
GSC 2461-00988, with a period P = 3.474474 d. As for HAT-P-32, the stellar and
planetary masses and radii of HAT-P-33 depend on the eccentricity, which is
poorly constrained due to the high jitter (~50m/s). In this case spectral line
bisector spans are significantly anti-correlated with the radial velocity
residuals, and we use this correlation to reduce the residual rms to ~35m/s. We
find the star has a mass of either 1.38+-0.04 M_sun or 1.40+-0.10 M_sun, and a
radius of either 1.64+-0.03 R_sun or 1.78+-0.28 R_sun, while the planet has a
mass of either 0.762+-0.101 MJ or 0.763+-0.117 MJ, and a radius of either
1.686+-0.045 RJ or 1.827+-0.290 RJ, for an assumed circular orbit or for the
best-fit eccentric orbit respectively. Due to the large bisector span
variations exhibited by both stars we rely on detailed modeling of the
photometric light curves to rule out blend scenarios. Both planets are among
the largest radii transiting planets discovered to date.
06/2011;
-
John Asher Johnson,
J. N. Winn, J. D. Hartman,
G. A. Bakos,
T. D. Morton,
G. Torres,
Géza Kovács,
D. W. Latham,
R. W. Noyes,
B. Sato, [......],
A. W. Howard,
S. N. Quinn,
B. Beky,
D. D. Sasselov,
R. P. Stefanik,
J. Lazar,
I. Papp,
P. Sari,
L. A. Buchhave,
G. Furesz
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of HAT-P-30b, a transiting exoplanet orbiting the
V=10.419 dwarf star GSC 0208-00722. The planet has a period
P=2.810595+/-0.000005 d, transit epoch Tc = 2455456.46561+/-0.00037 (BJD), and
transit duration 0.0887+/-0.0015 d. The host star has a mass of 1.24+/-0.04
Msun, radius of 1.21+/-0.05 Rsun, effective temperature 6304+/-88 K, and
metallicity [Fe/H] = +0.13+/-0.08. The planetary companion has a mass of
0.711+/-0.028 Mjup, and radius of 1.340+/-0.065 Rjup yielding a mean density of
0.37+/-0.05 g cm^-3. We also present radial velocity measurements that were
obtained throughout a transit that exhibit the Rossiter-McLaughlin effect. By
modeling this effect we measure an angle of \lambda = 73.5+/-9.0 deg between
the sky projections of the planet's orbit normal and the star's spin axis.
HAT-P-30b represents another example of a close-in planet on a highly tilted
orbit, and conforms to the previously noted pattern that tilted orbits are more
common around stars with Teff > 6250 K.
03/2011;
-
L. A. Buchhave,
G. A. Bakos, J. D. Hartman,
G. Torres,
D. W. Latham,
J. Andersen,
G. Kovacs,
R. W. Noyes,
A. Shporer,
G. A. Esquerdo, [......],
D. D. Sasselov,
G. Furesz,
S. N. Quinn,
R. P. Stefanik,
T. Szklenar,
P. Berlind,
M. L. Calkins,
J. Lazar,
I. Papp,
P. Sari
[show abstract]
[hide abstract]
ABSTRACT: We present the discovery of two transiting exoplanets. HAT-P-28b orbits a
V=13.03 G3 dwarf star with a period P = 3.2572 d and has a mass of 0.63 +- 0.04
MJ and a radius of 1.21 + 0.11 -0.08 RJ yielding a mean density of 0.44 +- 0.09
g cm-3. HAT-P-29b orbits a V=11.90 F8 dwarf star with a period P = 5.7232 d and
has a mass of 0.78 +0.08 -0.04 MJ and a radius of 1.11 +0.14 -0.08 RJ yielding
a mean density of 0.71 +- 0.18 g cm-3. We discuss the properties of these
planets in the context of other known transiting planets.
03/2011;
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J. D. Hartman,
G. Á. Bakos,
D. M. Kipping,
G. Torres,
G. Kovács,
R. W. Noyes,
D. W. Latham,
A. W. Howard,
D. A. Fischer,
J. A. Johnson, [......],
L. A. Buchhave,
B. Béky,
D. D. Sasselov,
R. P. Stefanik,
G. A. Esquerdo,
M. Everett,
G. Perumpilly,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of HAT-P-26b, a transiting extrasolar planet orbiting the moderately bright V = 11.744 K1 dwarf star GSC 0320–01027, with a period P = 4.234516 ± 0.000015 days, transit epoch Tc = 2455304.65122 ± 0.00035 (BJD; Barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time (UTC)), and transit duration 0.1023 ± 0.0010 days. The host star has a mass of 0.82 ± 0.03 M ☉, radius of 0.79+0.10 –0.04 R ☉, effective temperature 5079 ± 88 K, and metallicity [Fe/H] = -0.04 ± 0.08. The planetary companion has a mass of 0.059 ± 0.007 M J, and radius of 0.565+0.072 –0.032 R J yielding a mean density of 0.40 ± 0.10 g cm-3. HAT-P-26b is the fourth Neptune-mass transiting planet discovered to date. It has a mass that is comparable to those of Neptune and Uranus, and slightly smaller than those of the other transiting Super-Neptunes, but a radius that is ~65% larger than those of Neptune and Uranus, and also larger than those of the other transiting Super-Neptunes. HAT-P-26b is consistent with theoretical models of an irradiated Neptune-mass planet with a 10 M ⊕ heavy element core that comprises 50% of its mass with the remainder contained in a significant hydrogen-helium envelope, though the exact composition is uncertain as there are significant differences between various theoretical models at the Neptune-mass regime. The equatorial declination of the star makes it easily accessible to both Northern and Southern ground-based facilities for follow-up observations.
The Astrophysical Journal 01/2011; 728(2):138. · 6.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We summarize the contribution of the HATNet project to extrasolar planet
science, highlighting published planets (HAT-P-1b through HAT-P-26b). We also
briefly discuss the operations, data analysis, candidate selection and
confirmation procedures, and we summarize what HATNet provides to the exoplanet
community with each discovery.
01/2011;
-
J. D. Hartman,
G. Á. Bakos,
B. Sato,
G. Torres,
R. W. Noyes,
D. W. Latham,
G. Kovács,
D. A. Fischer,
A. W. Howard,
J. A. Johnson, [......],
G. Perumpilly,
B. Béky,
R. P. Stefanik,
D. D. Sasselov,
G. A. Esquerdo,
M. Everett,
Z. Csubry,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of two new transiting extrasolar planets. HAT-P-18b orbits the V = 12.759 K2 dwarf star GSC 2594–00646, with a period P = 5.508023 ± 0.000006 days, transit epoch Tc = 2454715.02174 ± 0.00020 (BJD), and transit duration 0.1131 ± 0.0009 days. The host star has a mass of 0.77 ± 0.03 M ☉, radius of 0.75 ± 0.04 R ☉, effective temperature 4803 ± 80 K, and metallicity [Fe/H] = +0.10 ± 0.08. The planetary companion has a mass of 0.197 ± 0.013 M J and radius of 0.995 ± 0.052 R J, yielding a mean density of 0.25 ± 0.04 g cm–3. HAT-P-19b orbits the V = 12.901 K1 dwarf star GSC 2283–00589, with a period P = 4.008778 ± 0.000006 days, transit epoch Tc = 2455091.53417 ± 0.00034 (BJD), and transit duration 0.1182 ± 0.0014 days. The host star has a mass of 0.84 ± 0.04 M ☉, radius of 0.82 ± 0.05 R ☉, effective temperature 4990 ± 130 K, and metallicity [Fe/H] = +0.23 ± 0.08. The planetary companion has a mass of 0.292 ± 0.018 M J and radius of 1.132 ± 0.072 R J, yielding a mean density of 0.25 ± 0.04 g cm–3. The radial velocity residuals for HAT-P-19 exhibit a linear trend in time, which indicates the presence of a third body in the system. Comparing these observations with theoretical models, we find that HAT-P-18b and HAT-P-19b are each consistent with a hydrogen-helium-dominated gas giant planet with negligible core mass. HAT-P-18b and HAT-P-19b join HAT-P-12b and WASP-21b in an emerging group of low-density Saturn-mass planets, with negligible inferred core masses. However, unlike HAT-P-12b and WASP-21b, both HAT-P-18b and HAT-P-19b orbit stars with super-solar metallicity. This calls into question the heretofore suggestive correlation between the inferred core mass and host star metallicity for Saturn-mass planets.
The Astrophysical Journal 12/2010; 726(1):52. · 6.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Candidate transiting planet systems discovered by wide-field ground-based surveys must go through an intensive follow-up procedure to distinguish the true transiting planets from the much more common false positives. Especially pernicious are configurations of three or more stars which produce radial velocity and light curves that are similar to those of single stars transited by a planet. In this contribution we describe the methods used by the HATNet team to reject these blends, giving a few illustrative examples. Comment: To appear in proceedings of the conference: "Detection and dynamics of transiting exoplanets" held at the OHP, 23-27 August 2010. 7 pages, 4 figures
11/2010;
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G. Kovács,
G. Á. Bakos, J. D. Hartman,
G. Torres,
R. W. Noyes,
D. W. Latham,
A. W. Howard,
D. A. Fischer,
J A Johnson,
G. W. Marcy,
H. Isaacson,
D. D. Sasselov,
R. P. Stefanik,
G. A. Esquerdo,
J. M. Fernandez,
B. Béky,
J. Lázár,
I. Papp,
P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of HAT-P-15b, a transiting extrasolar planet in the "period valley," a relatively sparsely populated period regime of the known extrasolar planets. The host star, GSC 2883-01687, is a G5 dwarf with V = 12.16. It has a mass of 1.01 ± 0.04 M_☉, radius of 1.08 ± 0.04 R_☉, effective temperature 5568 ± 90 K, and metallicity [Fe/H] = +0.22 ± 0.08. The planetary companion orbits the star with a period P = 10.863502 ± 0.000027 days, transit epoch T_c = 2454638.56019 ± 0.00048 (BJD), and transit duration 0.2285 ± 0.0015 days. It has a mass of 1.946 ± 0.066 M_J and radius of 1.072 ± 0.043 R_J yielding a mean density of 1.96 ± 0.22 g cm^(-3). At an age of 6.8^(+2.5))(–1.6) Gyr, the planet is H/He-dominated and theoretical models require about 2% (10 M_⊕) worth of heavy elements to reproduce its measured radius. With an estimated equilibrium temperature of ~820 K during transit, and ~1000 K at occultation, HAT-P-15b is a potential candidate to study moderately cool planetary atmospheres by transmission and occultation spectroscopy.
The Astrophysical Journal 11/2010; · 6.02 Impact Factor
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L. A. Buchhave,
G. Á. Bakos, J. D. Hartman,
G. Torres,
G. Kovács,
D. W. Latham,
R. W. Noyes,
G. A. Esquerdo,
M. Everett,
A. W. Howard, [......],
J. A. Johnson,
J. Andersen,
G. Fűrész,
G. Perumpilly,
D. D. Sasselov,
R. P. Stefanik,
B. Béky,
J. Lázár,
I. Papp,
and P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of HAT-P-16b, a transiting extrasolar planet orbiting the V = 10.8 mag F8 dwarf GSC 2792-01700, with a period P = 2.775960 ± 0.000003 days, transit epoch Tc = 2455027.59293 ± 0.00031 (BJD10), and transit duration 0.1276 ± 0.0013 days. The host star has a mass of 1.22 ± 0.04 M ☉, radius of 1.24 ± 0.05 R ☉, effective temperature 6158 ± 80 K, and metallicity [Fe/H] = +0.17 ± 0.08. The planetary companion has a mass of 4.193 ± 0.094 M J and radius of 1.289 ± 0.066 R J, yielding a mean density of 2.42 ± 0.35 g cm–3. Comparing these observed characteristics with recent theoretical models, we find that HAT-P-16b is consistent with a 1 Gyr H/He-dominated gas giant planet. HAT-P-16b resides in a sparsely populated region of the mass-radius diagram and has a non-zero eccentricity of e = 0.036 with a significance of 10σ.
The Astrophysical Journal 08/2010; 720(2):1118. · 6.02 Impact Factor
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G. Kovács,
G. Á. Bakos, J. D. Hartman,
G. Torres,
R. W. Noyes,
D. W. Latham,
A. W. Howard,
D. A. Fischer,
J A Johnson,
G. W. Marcy,
H. Isaacson,
D. D. Sasselov,
R. P. Stefanik,
G. A. Esquerdo,
J. M. Fernandez,
B. Béky,
J. Lázár,
I. Papp,
P. Sári
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of HAT-P-15b, a transiting extrasolar planet in the `period valley', a relatively sparsely-populated period regime of the known extrasolar planets. The host star, GSC 2883-01687, is a G5 dwarf with V=12.16. It has a mass of 1.01+/-0.04 M(Sun), radius of 1.08+/-0.04 R(Sun), effective temperature 5568+/-90 K, and metallicity [Fe/H] = +0.22+/-0.08. The planetary companion orbits the star with a period 10.863502+/-0.000027 days, transit epoch Tc = 2454638.56019+/-0.00048 (BJD), and transit duration 0.2285+/-0.0015 days. It has a mass of 1.946+/-0.066 M(Jup), and radius of 1.072+/-0.043 R(Jup) yielding a mean density of 1.96+/-0.22 g/cm3. At an age of 6.8+/-2.1 Gyr, the planet is H/He-dominated and theoretical models require about 2% (10 M(Earth)) worth of heavy elements to reproduce its measured radius. With an estimated equilibrium temperature of 820 K during transit, and 1000 K at occultation, HAT-P-15b is a potential candidate to study moderately cool planetary atmospheres by transmission and occultation spectroscopy. Comment: 12 pages with 10 figures and 6 tables in emulateapj format. Submitted to The Astrophysical Journal
05/2010;
-
L. A. Buchhave,
G. A. Bakos, J. D. Hartman,
G. Torres,
G. Kovacs,
D. W. Latham,
R. W. Noyes,
G. A. Esquerdo,
M. Everett,
A. W. Howard, [......],
J A Johnson,
J. Andersen,
G. Furesz,
G. Perumpilly,
D. D. Sasselov,
R. P. Stefanik,
B. Beky,
J. Lazar,
I. Papp,
P. Sari
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ABSTRACT: We report the discovery of HAT-P-16b, a transiting extrasolar planet orbiting the V = 10.8 mag F8 dwarf GSC 2792-01700, with a period P = 2.775960 +- 0.000003 d, transit epoch Tc = 2455027.59293 +- 0.00031 (BJD), and transit duration 0.1276 +- 0.0013 d. The host star has a mass of 1.22 +- 0.04 Msun, radius of 1.24 +- 0.05 Rsun, effective temperature 6158 +-80 K, and metallicity [Fe/H] = +0.17 +- 0.08. The planetary companion has a mass of 4.193 +- 0.094 MJ, and radius of 1.289 +- 0.066 RJ yielding a mean density of 2.42 +- 0.35 g/cm3. Comparing these observed characteristics with recent theoretical models, we find that HAT-P-16b is consistent with a 1 Gyr H/He-dominated gas giant planet. HAT-P-16b resides in a sparsely populated region of the mass{radius diagram and has a non-zero eccentricity of e = 0.036 with a significance of 10 sigma. Comment: Submitted to ApJ
05/2010;
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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
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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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ABSTRACT: Using light curves from the HATNet survey for transiting extrasolar planets
we investigate the optical broad-band photometric variability of a sample of
27,560 field K and M dwarfs selected by color and proper-motion. A total of
2120 stars exhibit potential variability, including 95 stars with eclipses and
60 stars with flares. Based on a visual inspection of these light curves and an
automated blending classification, we select 1568 stars, including 78 eclipsing
binaries, as secure variable star detections that are not obvious blends. We
estimate that a further ~26% of these stars may be blends with fainter
variables, though most of these blends are likely to be among the hotter stars
in our sample. We find that only 38 of the 1568 stars, including 5 of the
eclipsing binaries, have previously been identified as variables or are blended
with previously identified variables. One of the newly identified eclipsing
binaries is 1RXS J154727.5+450803, a known P = 3.55 day, late M-dwarf SB2
system, for which we derive preliminary estimates for the component masses and
radii of M_1 = M_2 = 0.258 +- 0.008 M_Sun and R_1 = R_2 = 0.289 +- 0.007 R_Sun.
The radii of the component stars are larger than theoretical expectations if
the system is older than ~200 Myr. The majority of the variables are heavily
spotted BY Dra-type stars for which we determine rotation periods. Using this
sample, we investigate the relations between period, color, age, and activity
measures, including optical flaring, for K and M dwarfs., finding that many of
the well-established relations for F, G and K dwarfs continue into the M dwarf
regime (Abridged).
07/2009;
