256 research outputs found
HAT-P-4b: A metal-rich low-density transiting hot Jupiter
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 d with a mid-transit 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 MJ, Rp= 1.27 +/- 0.05 RJ, rho = 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 of that of its parent star, this planet adds to the
theoretical challenges to explain inflated extrasolar planets.Comment: 5 pages, accepted for publication in ApJ
HAT-P-3b: A heavy-element rich planet transiting a K dwarf star
We report the discovery of a Jupiter-size planet transiting a relatively
bright (V = 11.56) and metal-rich early K dwarf star with a period of about 2.9
days. On the basis of follow-up photometry and spectroscopy we determine the
mass and radius of the planet, HAT-P-3b, to be M_p = 0.599 +/- 0.026 M_Jup and
R_p = 0.890 +/- 0.046 R_Jup. The relatively small size of the object for its
mass implies the presence of about 75 Earth masses worth of heavy elements (1/3
of the total mass) based on current theories of irradiated extrasolar giant
planets, similar to the mass of the core inferred for the transiting planet HD
149026b. The bulk density of HAT-P-3b is found to be rho_p = 1.06 +/- 0.17
g/cm^3, and the planet orbits the star at a distance of 0.03894 AU. Ephemerides
for the transit centers are T_c = 2,454,218.7594 +/- 0.0029 + N (2.899703 +/-
0.000054) (HJD).Comment: To appear in ApJ
HAT-P-17b,c: A Transiting, Eccentric, Hot Saturn and a Long-period, Cold Jupiter
We report the discovery of HAT-P-17b,c, a multi-planet system with an inner
transiting planet in a short-period, eccentric orbit and an outer planet in a
4.8 yr, nearly circular orbit. The inner planet, HAT-P-17b, transits the bright
V = 10.54 early K dwarf star GSC 2717-00417, with an orbital period P =
10.338523 +/- 0.000009 d, orbital eccentricity e = 0.346 +/- 0.007, transit
epoch T_c = 2454801.16945 +/- 0.00020, and transit duration 0.1691 +/- 0.0009
d. HAT-P-17b has a mass of 0.530 +/- 0.018 M_J and radius of 1.010 +/- 0.029
R_J yielding a mean density of 0.64 +/- 0.05 g cm^-3. This planet has a
relatively low equilibrium temperature in the range 780-927 K, making it an
attractive target for follow-up spectroscopic studies. The outer planet,
HAT-P-17c, has a significantly longer orbital period P_2 = 1797^+58_-89 d and a
minimum mass m_2 sin i_2 = 1.4^+1.1_-0.4 M_J. The orbital inclination of
HAT-P-17c is unknown as transits have not been observed and may not be present.
The host star has a mass of 0.86 +/- 0.04 M_Sun, radius of 0.84 +/- 0.02,
effective temperature 5246 +/- 80 K, and metallicity [Fe/H] = 0.00 +/- 0.08.
HAT-P-17 is the second multi-planet system detected from ground-based transit
surveys.Comment: Submitted to ApJ, 13 pages, 6 figures, 6 table
HAT-P-18b and HAT-P-19b: Two Low-Density Saturn-Mass Planets Transiting Metal-Rich K Stars
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 d, transit epoch Tc=2454715.02174+-0.00020 (BJD), and
transit duration 0.1131+-0.0009 d. The host star has a mass of 0.77+-0.03 Msun,
radius of 0.75+-0.04 Rsun, effective temperature 4803+-80 K, and metallicity
[Fe/H]=+0.10+-0.08. The planetary companion has a mass of 0.197+-0.013 Mjup,
and radius of 0.995+-0.052 Rjup 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 d, transit epoch Tc=2455091.53417+-0.00034 (BJD), and
transit duration 0.1182+-0.0014 d. The host star has a mass of 0.84+-0.04 Msun,
radius of 0.82+-0.05 Rsun, effective temperature 4990+-130 K, and metallicity
[Fe/H]=+0.23+-0.08. The planetary companion has a mass of 0.292+-0.018 Mjup,
and radius of 1.132+-0.072 Rjup 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.Comment: 18 pages, 11 figures, 9 tables. Replaced with version accepted for
publication in Ap
Hat-P-25b: A Hot-Jupiter Transiting a Moderately Faint G Star
We report the discovery of HAT-P-25b, a transiting extrasolar planet orbiting the V = 13.19 G5 dwarf star GSC 1788-01237, with a period P = 3.652836 ± 0.000019 days, transit epoch T_c = 2455176.85173 ± 0.00047 (BJD—barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time, UTC), and transit duration 0.1174 ± 0.0017 days. The host star has a mass of 1.01 ± 0.03 M_☉, radius of 0.96^(+0.05)_(– 0.04) R_☉, effective temperature 5500 ± 80 K, and metallicity [Fe/H] = +0.31 ± 0.08. The planetary companion has a mass of 0.567 ± 0.022 M_J and radius of 1.190^(+0.081)_(–0.056) R_J yielding a mean density of 0.42 ± 0.07 g cm^(–3)
HAT-P-56b: An inflated massive Hot Jupiter transiting a bright F star followed up with K2 Campaign 0 observations
We report the discovery of HAT-P-56b by the HATNet survey, an inflated hot
Jupiter transiting a bright F type star in Field 0 of NASA's K2 mission. We
combine ground-based discovery and follow-up light curves with high precision
photometry from K2, as well as ground-based radial velocities from TRES on the
FLWO 1.5m telescope to determine the physical properties of this system.
HAT-P-56b has a mass of , radius of , and transits its host
star on a near-grazing orbit with a period of 2.7908 d. The radius of HAT-P-56b
is among the largest known for a planet with . The host star has a
V-band magnitude of 10.9, mass of 1.30 , and radius of 1.43 .
The periodogram of the K2 light curve suggests the star is a Dor
variable. HAT-P-56b is an example of a ground-based discovery of a transiting
planet, where space-based observations greatly improve the confidence in the
confirmation of its planetary nature, and also improve the accuracy of the
planetary parameters.Comment: 13 pages, 11 figures, accepted by A
Hat-P-28b and Hat-P-29b: Two Sub-Jupiter Mass Transiting Planets
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 days and has a mass of 0.63 ± 0.04 M_J and a radius of 1.21^(+0.11)_(–0.08) R_J 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 days and has a mass of 0.78^(+0.08)_(–0.04) M_J and a radius of 1.11^(+0.14)_(–0.08) R_J 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
HAT-P-6b: A Hot Jupiter transiting a bright F star
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 mid-transit epoch 2,454,035.67575 +/- 0.00028
(HJD). The parent star is a late F star with mass 1.29 +/- 0.06 Msun, radius
1.46 +/- 0.06 Rsun, Teff ~ 6570 +/- 80 K, [Fe=H] = -0.13 +/- 0.08 and age ~
2.3+/-^{0.5}_{0.7}Gy. 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.Comment: Accepted for publication in ApJL, 5 pages, minor changes compared to
V
Hat-P-20b-Hat-p-23b: Four Massive Transiting Extrasolar Planets
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 ± 0.000004 days, transit epoch T_c = 2455080.92661 ± 0.00021 (BJD_(UTC)), and transit duration 0.0770 ± 0.0008 days. The host star has a mass of 0.76 ± 0.03 M_☉, radius of 0.69 ± 0.02 R_☉, effective temperature 4595 ± 80 K, and metallicity [Fe/H] = +0.35 ± 0.08. The planetary companion has a mass of 7.246 ± 0.187 M_J and a radius of 0.867 ± 0.033 R_J yielding a mean density of 13.78 ± 1.50 g 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 ± 0.000007 days, transit epoch T_c = 2454996.41312 ± 0.00069, and transit duration 0.1530 ± 0.0027 days. The host star has a mass of 0.95 ± 0.04 M_☉, radius of 1.10 ± 0.08 R_☉, effective temperature 5588 ± 80 K, and metallicity [Fe/H] = +0.01 ± 0.08. The planetary companion has a mass of 4.063 ± 0.161 M_J and a radius of 1.024 ± 0.092 R_J yielding a mean density of 4.68^(+1.59)_(–0.99) g 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 ± 0.000009 days, transit epoch T_c = 2454930.22001 ± 0.00025, and transit duration 0.1196 ± 0.0014 days. The host star has a mass of 0.92 ± 0.03 M_☉, radius of 1.04 ± 0.04 R_☉, effective temperature 5302 ± 80 K, and metallicity [Fe/H] = +0.24 ± 0.08. The planet has a mass of 2.147 ± 0.061 M_J and a compact radius of 1.080 ± 0.058 R_J yielding a mean density of 2.11^(+0.40)_(–0.29) g 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 ± 0.000002 days, transit epoch T_c = 2454852.26464 ± 0.00018, and transit duration 0.0908 ± 0.0007 days. The host star has a mass of 1.13 ± 0.04 M_☉, radius of 1.20 ± 0.07 R_☉, effective temperature 5905 ± 80 K, and metallicity [Fe/H] = +0.15 ± 0.04. The planetary companion has a mass of 2.090 ± 0.111 M_J and a radius of 1.368 ± 0.090 R_J yielding a mean density of 1.01 ± 0.18 g 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)_(–1.8) Myr) before it gets engulfed by the star
HAT-P-26b: A Low-Density Neptune-Mass Planet Transiting a K Star
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 d, transit epoch Tc = 2455304.65122 +- 0.00035 (BJD), and
transit duration 0.1023 +- 0.0010 d. The host star has a mass of 0.82 +- 0.03
Msun, radius of 0.79 + 0.10 - 0.04 Rsun, effective temperature 5079 +- 88 K,
and metallicity [Fe/H] = -0.04 +- 0.08. The planetary companion has a mass of
0.059 +- 0.007 MJ, and radius of 0.565 + 0.072 - 0.032 RJ 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 Mearth 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.Comment: 16 pages, 9 figures, 5 tables, submitted to Ap
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