We report the discovery of two exoplanets transiting high-jitter stars. HAT-P-32b orbits the bright V = 11.289 late-F-early-G dwarf star GSC 3281-00800, with a period P = 2.150008 ? 0.000001 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 (~80 m s--1). Assuming a circular orbit, the star has a mass of 1.16 ? 0.04 M and radius of 1.22 ? 0.02 R , while the planet has a mass of 0.860 ? 0.164 M J and a radius of 1.789 ? 0.025 R J. The second planet, HAT-P-33b, orbits the bright V = 11.188 late-F dwarf star GSC 2461-00988, with a period P = 3.474474 ? 0.000001 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 (~50 m s--1). In this case, spectral line bisector spans (BSs) are significantly anti-correlated with the radial velocity residuals, and we are able to use this correlation to reduce the residual rms to ~35 m s--1. We find that the star has a mass of 1.38 ? 0.04 M and a radius of 1.64 ? 0.03 R while the planet has a mass of 0.762 ? 0.101 M J and a radius of 1.686 ? 0.045 R J for an assumed circular orbit. Due to the large BS 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.
Abstract
We report the discovery of 10 transiting extrasolar planets by the HATSouth survey. The planets range in mass from the super-Neptune HATS-62b, with
, to the super-Jupiter HATS-66b, with
, ...and in size from the Saturn HATS-69b, with
, to the inflated Jupiter HATS-67b, with
. The planets have orbital periods between
days (HATS-67b) and
days (HATS-61b). The hosts are dwarf stars with masses ranging from
(HATS-69) to
(HATS-64) and have apparent magnitudes between
mag (HATS-68) and
mag (HATS-66). The super-Neptune HATS-62b is the least massive planet discovered to date with a radius larger than Jupiter. Based largely on the
Gaia
DR2 distances and broadband photometry, we identify three systems (HATS-62, HATS-64, and HATS-65) as having possible unresolved binary star companions. We discuss in detail our methods for incorporating the
Gaia
DR2 observations into our modeling of the system parameters and into our blend analysis procedures.
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 {circled plus} core. With an equilibrium temperature of T eq = 1020 ± 17 K, HAT-P-10b is one of the coldest TEPs. Curiously, its Safronov number c = 0.053 ± 0.002 falls close to the dividing line between the two suggested TEP populations.
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{sub +}, 3.8 R{sub +}) both in mass M{sub p} = 0.081 +- 0.009 M{sub J}(25.8 +- 2.9 M{sub +}) and radius R{sub p} = 0.422 +- 0.014 R{sub J}(4.73 +- 0.16 R{sub +}). HAT-P-11b orbits in an eccentric orbit with e = 0.198 +- 0.046 and omega = 355.{sup 0}2 +- 17.{sup 0}3, causing a reflex motion of its parent star with amplitude 11.6 +- 1.2 m s{sup -1}, a challenging detection due to the high level of chromospheric activity of the parent star. Our ephemeris for the transit events is T{sub c} = 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{sub *} = 0.809{sup +0.020}{sub -0.027} M{sub sun}, R{sub *} = 0.752 +- 0.021 R{sub sun}, and T{sub 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.
We report the discovery and characterization of four transiting exoplanets by the HATNet survey. The planet HAT-P-50b has a mass of 1.35 M sub(J) and radius of 1.29 R sub(J), and orbits a bright (V = ...11.8 mag) M = 1.27 M sub(middot in circle), R = 1.70 R sub(middot in circle) star every P = 3.1220 days. The planet HAT-P-51b has a mass of 0.31 M sub(J) and radius of 1.29 R sub(J) and orbits a V = 13.4 mag, M = 0.98 M sub(middot in circle), R = 1.04 R sub(middot in circle) star with a period of P = 4.2180 days. The planet HAT-P-52b has a mass of 0.82M sub(J) and radius of 1.01 R sub(J), and orbits a V = 14.1 mag, M = 0.89 M sub(middot in circle), R = 0.89 R sub(middot in circle) star with a period of P = 2.7536 days. The planet HAT-P-53b has a mass of 1.48 M sub(J) and radius of 1.32 R sub(J), and orbits a V = 13.7 mag, M = 1.09 M sub(middot in circle), R = 1.21 R sub(middot in circle) star with a period of P = 1.9616 days. All four planets are consistent with having circular orbits and have masses and radii measured to better than 10% precision. The low stellar jitter and favorable Rp/Rlow * ratio for HAT-P-51 make it a promising target for measuring the Rossiter-McLaughlin effect for a Saturn-mass planet.
In the ongoing HATNet survey we have detected a giant planet, with radius 1.33 plus or minus 0.06 R sub(Jup) and mass 1.06 plus or minus 0.12 M sub(Jup), transiting the bright (V = 10.5) star GSC ...03239-00992. The planet is in a circular orbit with period 3.852985 plus or minus 0.000005 days and midtransit epoch 2,454,035.67575 plus or minus 0.00028 (HJD). The parent star is a late F star with mass 1.29 plus or minus 0.06 M unk, radius 1.46 plus or minus 0.06 R unk, T sub(off) similar to 6570 plus or minus 80 K, Fe/H = -0.13 plus or minus 0.08, and age similar to 2.3 super(+) sub(-) super(0) sub(0) super(.) sub(.) super(5) sub(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.
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 {circled plus}. HAT-P-12b is thus the least massive H/He-dominated gas giant planet found to date. This record was previously held by Saturn.
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 Tc = 2455080.92661 ? 0.00021 (BJDUTC), 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 Tc = 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 Tc = 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 Tc = 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.
Abstract
We report the discovery of four short-period extrasolar planets transiting moderately bright stars from photometric measurements of the HATSouth network coupled to additional spectroscopic ...and photometric follow-up observations. While the planet masses range from 0.26 to 0.90
, the radii are all approximately a Jupiter radii, resulting in a wide range of bulk densities. The orbital period of the planets ranges from 2.7 days to 4.7 days, with HATS-43b having an orbit that appears to be marginally non-circular (
e
= 0.173 ± 0.089). HATS-44 is notable for having a high metallicity (
= 0.320 ± 0.071). The host stars spectral types range from late F to early K, and all of them are moderately bright (13.3 <
V
< 14.4), allowing the execution of future detailed follow-up observations. HATS-43b and HATS-46b, with expected transmission signals of 2350 ppm and 1500 ppm, respectively, are particularly well suited targets for atmospheric characterization via transmission spectroscopy.
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