Abstract
The relative rarity of giant planets around low-mass stars compared with solar-type stars is a key prediction from the core-accretion planet formation theory. In this paper we report on the ...discovery of four gas giant planets that transit low-mass late K and early M dwarfs. The planets HATS-74Ab (TOI 737b), HATS-75b (TOI 552b), HATS-76b (TOI 555b), and HATS-77b (TOI 730b) were all discovered from the HATSouth photometric survey and follow-up using TESS and other photometric facilities. We use the new ESPRESSO facility at the VLT to confirm systems and measure their masses. We find that these planets have masses of 1.46 ± 0.14
M
J, 0.491 ± 0.039
M
J, 2.629 ± 0.089
M
J, and
1.374
−
0.074
+
0.100
M
J, respectively, and radii of 1.032 ± 0.021
R
J, 0.884 ± 0.013
R
J, 1.079 ± 0.031
R
J, and 1.165 ± 0.021
R
J, respectively. The planets all orbit close to their host stars with orbital periods ranging from 1.7319 days to 3.0876 days. With further work, we aim to test core-accretion theory by using these and further discoveries to quantify the occurrence rate of giant planets around low-mass host stars.
Abstract
We report the discovery of HATS-70b, a transiting brown dwarf at the deuterium burning limit. HATS-70b has a mass of
and a radius of
, residing in a close-in orbit with a period of
days. The ...host star is a
A star rotating at
, enabling us to characterize the spectroscopic transit of the brown dwarf via Doppler tomography. We find that HATS-70b, like other massive planets and brown dwarfs previously sampled, orbits in a low projected-obliquity orbit with
. The low obliquities of these systems is surprising given all brown dwarf and massive planets with obliquities measured orbit stars hotter than the Kraft break. This trend is tentatively inconsistent with dynamically chaotic migration for systems with massive companions, though the stronger tidal influence of these companions makes it difficult to draw conclusions on the primordial obliquity distribution of this population. We also introduce a modeling scheme for planets around rapidly rotating stars, accounting for the influence of gravity darkening on the derived stellar and planetary parameters.
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 the discovery by the HATSouth network of HATS-18b: a (ProQuest: Formulae and/or non-USASCII text omitted) planet in a 0.8378 day orbit, around a solar analog star (mass 1.037 + or - 0.047 ...Mmiddot in circle and radius (ProQuest: Formulae and/or non-USASCII text omitted) Rmiddot in circle) V= 14.067 + or - 0.040 mag. The high planet mass, combined with its short orbital period, implies strong tidal coupling between the planetary orbit and the star. In fact, given its inferred age, HATS-18 shows evidence of significant tidal spin up, which together with WASP-19 (a very similar system) allows us to constrain the tidal quality factor for Sun-like stars to be in the range of 6.5 <, ~ log sub(10)(Q*/k sub(2)) <, ~ 7 even after allowing for extremely pessimistic model uncertainties. In addition, the HATS-18 system is among the best systems (and often the best system) for testing a multitude of star-planet interactions, be they gravitational, magnetic, or radiative, as well as planet formation and migration theories.
We observed the open clusters M35 and NGC 2158 during the initial K2 campaign (C0). Reducing these data to high-precision photometric timeseries is challenging due to the wide point-spread function ...(PSF) and the blending of stellar light in such dense regions. We developed an image-subtraction-based K2 reduction pipeline that is applicable to both crowded and sparse stellar fields. We applied our pipeline to the data-rich C0 K2 super stamp, containing the two open clusters, as well as to the neighboring postage stamps. In this paper, we present our image subtraction reduction pipeline and demonstrate that this technique achieves ultra-high photometric precision for sources in the C0 super stamp. We extract the raw light curves of 3960 stars taken from the UCAC4 and EPIC catalogs and de-trend them for systematic effects. We compare our photometric results with the prior reductions published in the literature. For de-trended TFA-corrected sources in the 12-12.25 K p magnitude range, we achieve a best 6.5-hour window running rms of 35 ppm, falling to 100 ppm for fainter stars in the 14-14.25 K p magnitude range. For stars with K p > 14 , our de-trended and 6.5-hour binned light curves achieve the highest photometric precision. Moreover, all our TFA-corrected sources have higher precision on all timescales investigated. This work represents the first published image subtraction analysis of a K2 super stamp. This method will be particularly useful for analyzing the Galactic bulge observations carried out during K2 campaign 9. The raw light curves and the final results of our de-trending processes are publicly available at http://k2.hatsurveys.org/archive/.
As described in sect; 2.3, each HSsub 4 unit is controlled by a single control computer running Linux with a special kernel that is capable of real-time operations. In addition, a node-computer is ...responsible for weather sensing and synchronizing the time to the GPS time. A large suite of software is running on the control and node computers, responsible for the instrument control. We broadly classify the control software components to "low-level", meaning direct control of instruments, and "high-level", referring to more general observatory control, usually connected to the "low-level" software. The control of the telescope mount is performed through a Xenomai-based (real-time) character device driver, called the scope module. This module depends on the basic built-in printer port control modules of Linux. When the scope kernel module is loaded, a number of initial parameters are supplied, such as the choice of the hemisphere (to determine the direction of tracking), the resolution of the axes, settings for ramping up the motors to maximal slewing speed, and the level of verbosity.
We report the discovery by the HATSouth survey of HATS-4b, an extrasolar planet transiting a V = 13.46 mag G star. HATS-4b has a period of P approximately 2.5167 days, mass of M sub(p) approximately ...1.32 M sub(Jup), radius of R sub(p) approximately 1.02 R sub(Jup), and density of rho sub(p) = 1.55 + or - 0.16 g cm super(-3) approximately 1.24 rho sub(Jup). The host star has a mass of 1.00 M sub(odot), a radius of 0.92 R sub(odot), and a very high metallicity Fe/H = 0.43 + or - 0.08. HATS-4b is among the densest known planets with masses between 1 and 2 M sub(J) and is thus likely to have a significant content of heavy elements of the order of 75 M sub(+ in circle). In this paper we present the data reduction, radial velocity measurements, and stellar classification techniques adopted by the HATSouth survey for the CORALIE spectrograph. We also detail a technique for simultaneously estimating v sin i and macroturbulence using high resolution spectra.
We report the discovery by the HATSouth survey of HATS-6b, an extrasolar planet transiting a V = 15.2 mag, i = 13.7 mag M1V star with a mass of 0.57 M sub(middot in circle) and a radius of 0.57 R ...sub(middot in circle). HATS-6b has a period of P = 3.3253 d, mass of M sub(p) = 0.32 M sub(J) , radius of R sub(p) = 1.00 R sub(J) , and zero-albedo equilibrium temperature of T sub(eq) = 712.8 + or - 5.1 K. HATS-6 is one of the lowest mass stars known to host a close-in gas giant planet, and its transits are among the deepest of any known transiting planet system. We show that from the transit-based stellar density alone it is possible to measure the mass and radius of a ~0.6 M sub(middot in circle) star to ~7 and ~2% precision, respectively.
We report the discovery of four transiting F-M binary systems with companions between 0.1 and 0.2 M in mass by the HATSouth survey. These systems have been characterized via a global analysis of the ...HATSouth discovery data, combined with high-resolution radial velocities and accurate transit photometry observations. We determined the masses and radii of the component stars using a combination of two methods: isochrone fitting of spectroscopic primary star parameters and equating spectroscopic primary star rotation velocity with spin-orbit synchronization. These new very low mass companions are HATS550-016B (
,
), HATS551-019B (
,
), HATS551-021B (
,
) and HATS553-001B (
,
). We examine our sample in the context of the radius anomaly for fully convective low-mass stars. Combining our sample with the 13 other well-studied very low mass stars, we find a tentative 5 per cent systematic deviation between the measured radii and theoretical isochrone models.
ABSTRACT
We present the discovery of the transiting exoplanets HAT-P-65b and HAT-P-66b, with orbital periods of
and
days, masses of
and
, and inflated radii of
and
, respectively. They orbit ...moderately bright (
and
) stars of mass
and
. The stars are at the main-sequence turnoff. While it is well known that the radii of close-in giant planets are correlated with their equilibrium temperatures, whether or not the radii of planets increase in time as their hosts evolve and become more luminous is an open question. Looking at the broader sample of well-characterized close-in transiting giant planets, we find that there is a statistically significant correlation between planetary radii and the fractional ages of their host stars, with a false-alarm probability of only 0.0041%. We find that the correlation between the radii of planets and the fractional ages of their hosts is fully explained by the known correlation between planetary radii and their present-day equilibrium temperatures; however, if the zero-age main-sequence equilibrium temperature is used in place of the present-day equilibrium temperature, then a correlation with age must also be included to explain the planetary radii. This suggests that, after contracting during the pre-main-sequence, close-in giant planets are reinflated over time due to the increasing level of irradiation received from their host stars. Prior theoretical work indicates that such a dynamic response to irradiation requires a significant fraction of the incident energy to be deposited deep within the planetary interiors.
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