Abstract
Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their ...parent stars. We report the discovery of HAT-P-69 b (TOI 625.01) and HAT-P-70 b (TOI 624.01), two new hot Jupiters around A stars from the Hungarian-made Automated Telescope Network (HATNet) survey that have also been observed by the
Transiting Exoplanet Survey Satellite
. HAT-P-69 b has a mass of
M
Jup
and a radius of
R
Jup
and resides in a prograde 4.79 day orbit. HAT-P-70 b has a radius of
R
Jup
and a mass constraint of
M
Jup
and resides in a retrograde 2.74 day orbit. We use the confirmation of these planets around relatively massive stars as an opportunity to explore the occurrence rate of hot Jupiters as a function of stellar mass. We define a sample of 47,126 main-sequence stars brighter than
T
mag
= 10 that yields 31 giant planet candidates, including 18 confirmed planets, 3 candidates, and 10 false positives. We find a net hot Jupiter occurrence rate of 0.41 ± 0.10% within this sample, consistent with the rate measured by
Kepler
for FGK stars. When divided into stellar mass bins, we find the occurrence rate to be 0.71 ± 0.31% for G stars, 0.43 ± 0.15% for F stars, and 0.26 ± 0.11% for A stars. Thus, at this point, we cannot discern any statistically significant trend in the occurrence of hot Jupiters with stellar mass.
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 of HATS-71b, a transiting gas giant planet on a day orbit around a mag M3 dwarf star. HATS-71 is the coolest M dwarf star known to host a hot Jupiter. The loss of light during ...transits is 4.7%, more than in any other confirmed transiting planet system. The planet was identified as a candidate by the ground-based HATSouth transit survey. It was confirmed using ground-based photometry, spectroscopy, and imaging, as well as space-based photometry from the NASA Transiting Exoplanet Survey Satellite mission (TIC 234523599). Combining all of these data, and utilizing Gaia DR2, we find that the planet has a radius of and mass of (95% confidence upper limit of ), while the star has a mass of and a radius of .
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 two transiting Neptunes by the HATSouth survey. The planet HATS-37Ab has a mass of
(31.5 ± 13.4
M
⊕
) and a radius of
, and is on a
day orbit around a
mag,
star ...with a radius of
. We also present evidence that the star HATS-37A has an unresolved stellar companion HATS-37B, with a photometrically estimated mass of
. The planet HATS-38b has a mass of
(23.5 ± 3.5
M
⊕
) and a radius of
, and is on a
day orbit around a
mag,
star with a radius of
. Both systems appear to be old, with isochrone-based ages of
Gyr, and
Gyr, respectively. Both HATS-37Ab and HATS-38b lie in the Neptune desert and are thus examples of a population with a low occurrence rate. They are also among the lowest-mass planets found from ground-based wide-field surveys to date.
Anticancer peptides (ACPs) could potentially offer many advantages over other cancer therapies. ACPs often target cell membranes, where their surface mechanism is coupled to a conformational change ...into helical structures. However, details on their binding are still unclear, which would be crucial to reach progress in connecting structural aspects to ACP action and to therapeutic developments. Here we investigated natural helical ACPs, Lasioglossin LL-III, Macropin 1, Temporin-La, FK-16, and LL-37, on model liposomes, and also on extracellular vesicles (EVs), with an outer leaflet composition similar to cancer cells. The combined simulations and experiments identified three distinct binding modes to the membranes. Firstly, a highly helical structure, lying mainly on the membrane surface; secondly, a similar, yet only partially helical structure with disordered regions; and thirdly, a helical monomeric form with a non-inserted perpendicular orientation relative to the membrane surface. The latter allows large swings of the helix while the N-terminal is anchored to the headgroup region. These results indicate that subtle differences in sequence and charge can result in altered binding modes. The first two modes could be part of the well-known carpet model mechanism, whereas the newly identified third mode could be an intermediate state, existing prior to membrane insertion.
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.
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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