234 research outputs found
HATS-6b: A Warm Saturn Transiting an Early M Dwarf Star, and a Set of Empirical Relations for Characterizing K and M Dwarf Planet Hosts
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 Msun
and a radius of 0.57 Rsun. HATS-6b has a period of P = 3.3253 d, mass of
Mp=0.32 Mjup, radius of Rp=1.00 Rjup, and zero-albedo equilibrium temperature
of Teq=712.8+-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 discuss the follow-up opportunities afforded by
this system, noting that despite the faintness of the host star, it is expected
to have the highest K-band S/N transmission spectrum among known gas giant
planets with Teq < 750 K. In order to characterize the star we present a new
set of empirical relations between the density, radius, mass, bolometric
magnitude, and V, J, H and K-band bolometric corrections for main sequence
stars with M < 0.80 Msun, or spectral types later than K5. These relations are
calibrated using eclipsing binary components as well as members of resolved
binary systems. We account for intrinsic scatter in the relations in a
self-consistent manner. We show that from the transit-based stellar density
alone it is possible to measure the mass and radius of a ~0.6 Msun star to ~7%
and ~2% precision, respectively. Incorporating additional information, such as
the V-K color, or an absolute magnitude, allows the precision to be improved by
up to a factor of two.Comment: 21 pages, 11 figures, 10 tables. Submitted to AJ. Data available at
http://hatsouth.org Code implementing empirical model available at
http://www.astro.princeton.edu/~jhartman/kmdwarfparam.htm
HATS-3b: An inflated hot Jupiter transiting an F-type star
We report the discovery by the HATSouth survey of HATS-3b, a transiting
extrasolar planet orbiting a V=12.4 F-dwarf star. HATS-3b has a period of P =
3.5479d, mass of Mp = 1.07MJ, and radius of Rp = 1.38RJ. Given the radius of
the planet, the brightness of the host star, and the stellar rotational
velocity (vsini = 9.0km/s), this system will make an interesting target for
future observations to measure the Rossiter-McLaughlin effect and determine its
spin-orbit alignment. We detail the low/medium-resolution reconnaissance
spectroscopy that we are now using to deal with large numbers of transiting
planet candidates produced by the HATSouth survey. We show that this important
step in discovering planets produces logg and Teff parameters at a precision
suitable for efficient candidate vetting, as well as efficiently identifying
stellar mass eclipsing binaries with radial velocity semi-amplitudes as low as
1 km/s.Comment: 11 pages, 10 figures, submitted to A
HATS-5b: A Transiting hot-Saturn from the HATSouth Survey
We report the discovery of HATS-5b, a transiting hot-Saturn orbiting a G type
star, by the HAT-South survey. HATS-5b has a mass of Mp=0.24 Mj, radius of
Rp=0.91 Rj, and transits its host star with a period of P=4.7634d. The radius
of HATS-5b is consistent with both theoretical and empirical models. The host
star has a V band magnitude of 12.6, mass of 0.94 Msun, and radius of 0.87
Rsun. The relatively high scale height of HATS-5b, and the bright,
photometrically quiet host star, make this planet a favourable target for
future transmission spectroscopy follow-up observations. We reexamine the
correlations in radius, equilibrium temperature, and metallicity of the
close-in gas-giants, and find hot Jupiter-mass planets to exhibit the strongest
dependence between radius and equilibrium temperature. We find no significant
dependence in radius and metallicity for the close-in gas-giant population.Comment: 10 pages, submitted to A
HATS-15 b and HATS-16 b: Two massive planets transiting old G dwarf stars
We report the discovery of HATS-15 b and HATS-16 b, two massive transiting
extrasolar planets orbiting evolved ( Gyr) main-sequence stars. The
planet HATS-15 b, which is hosted by a G9V star ( mag), is a hot
Jupiter with mass of and radius of
, and completes its orbit in nearly 1.7 days.
HATS-16 b is a very massive hot Jupiter with mass of and radius of ; it orbits around
its G3 V parent star ( mag) in days. HATS-16 is slightly
active and shows a periodic photometric modulation, implying a rotational
period of 12 days which is unexpectedly short given its isochronal age. This
fast rotation might be the result of the tidal interaction between the star and
its planet.Comment: 16 pages, 8 figures, submitted to PAS
HATS-17b: A Transiting Compact Warm Jupiter in a 16.3 Days Circular Orbit
We report the discovery of HATS-17b, the first transiting warm Jupiter of the
HATSouth network. HATS-17b transits its bright (V=12.4) G-type
(M=1.131 0.030 M,
R=1.091 R) metal-rich ([Fe/H]=+0.3 dex)
host star in a circular orbit with a period of P=16.2546 days. HATS-17b has a
very compact radius of 0.777 0.056 R given its Jupiter-like mass of
1.338 0.065 M. Up to 50% of the mass of HATS-17b may be composed of
heavy elements in order to explain its high density with current models of
planetary structure. HATS-17b is the longest period transiting planet
discovered to date by a ground-based photometric survey, and is one of the
brightest transiting warm Jupiter systems known. The brightness of HATS-17b
will allow detailed follow-up observations to characterize the orbital geometry
of the system and the atmosphere of the planet.Comment: 12 page, 8 figures, submitted to A
HATS-11b and HATS-12b: Two transiting Hot Jupiters orbiting sub-solar metallicity stars selected for the K2 Campaign 7
We report the discovery of two transiting extrasolar planets from the
HATSouth survey. HATS-11, a V=14.1 G0-star shows a periodic 12.9 mmag dip in
its light curve every 3.6192 days and a radial velocity variation consistent
with a Keplerian orbit. HATS-11 has a mass of 1.000 0.060 M, a
radius of 1.444 0.057 M and an effective temperature of 6060
150 K, while its companion is a 0.85 0.12 M, 1.510 0.078
R planet in a circular orbit. HATS-12 shows a periodic 5.1 mmag flux
decrease every 3.1428 days and Keplerian RV variations around a V=12.8 F-star.
HATS-12 has a mass of 1.489 0.071 M, a radius of 2.21
0.21 R, and an effective temperature of 6408 75 K. For HATS-12,
our measurements indicate that this is a 2.38 0.11 M, 1.35 0.17
R planet in a circular orbit. Both host stars show sub-solar metallicity of
-0.390 0.060 dex and -0.100 0.040 dex, respectively and are
(slightly) evolved stars. In fact, HATS-11 is amongst the most metal-poor and,
HATS-12 is amongst the most evolved stars hosting a hot Jupiter planet.
Importantly, HATS-11 and HATS-12 have been observed in long cadence by Kepler
as part of K2 campaign 7 (EPIC216414930 and EPIC218131080 respectively).Comment: 14 pages, 7 figures, 6 tables, submitted to A
HATS-18 b: An Extreme Short--Period Massive Transiting Planet Spinning Up Its Star
We report the discovery by the HATSouth network of HATS-18 b: a 1.980 +/-
0.077 Mj, 1.337 +0.102 -0.049 Rj planet in a 0.8378 day orbit, around a solar
analog star (mass 1.037 +/- 0.047 Msun, and radius 1.020 +0.057 -0.031 Rsun)
with V=14.067 +/- 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 6.5 <= lg(Q*/k_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.Comment: Submitted. 12 pages, 9 figures, 5 table
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