259 research outputs found
The Mass-Radius Relationship for Very Low Mass Stars: Four New Discoveries from the HATSouth Survey
We report the discovery of four transiting F-M binary systems with companions
between 0.1-0.2 Msun in mass by the HATSouth survey. These systems have been
characterised 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 synchronisation. These new very low mass companions are HATS550-016B
(0.110 -0.006/+0.005 Msun, 0.147 -0.004/+0.003 Rsun), HATS551-019B (0.17
-0.01/+0.01 Msun, 0.18 -0.01/+0.01 Rsun), HATS551-021B (0.132 -0.005/+0.014
Msun, 0.154 -0.008/+0.006 Rsun), HATS553-001B (0.20 -0.02/+0.01 Msun, 0.22
-0.01/+0.01 Rsun). 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% systematic deviation
between the measured radii and theoretical isochrone models.Comment: 17 pages, 8 figures, accepted for publication in MNRA
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-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-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-9b and HATS-10b: Two Compact Hot Jupiters in Field 7 of the K2 Mission
We report the discovery of two transiting extrasolar planets by the HATSouth
survey. HATS-9b orbits an old (10.8 1.5 Gyr) V=13.3 G dwarf star, with a
period P = 1.9153 d. The host star has a mass of 1.03 M, radius of
1.503 R and effective temperature 5366 70 K. The planetary
companion has a mass of 0.837 M, and radius of 1.065 R yielding a mean
density of 0.85 g cm . HATS-10b orbits a V=13.1 G dwarf star, with a
period P = 3.3128 d. The host star has a mass of 1.1 M, radius of 1.11
R and effective temperature 5880 120 K. The planetary companion
has a mass of 0.53 M, and radius of 0.97 R yielding a mean density of
0.7 g cm . Both planets are compact in comparison with planets receiving
similar irradiation from their host stars, and lie in the nominal coordinates
of Field 7 of K2 but only HATS-9b falls on working silicon. Future
characterisation of HATS-9b with the exquisite photometric precision of the
Kepler telescope may provide measurements of its reflected light signature.Comment: 15 pages, 10 figures, accepted for publication in A
HATS-13b and HATS-14b: two transiting hot Jupiters from the HATSouth survey
We report the discovery of HATS-13b and HATS-14b, two hot-Jupiter transiting
planets discovered by the HATSouth survey. The host stars are quite similar to
each other (HATS-13: V = 13.9 mag, M* = 0.96 Msun, R* = 0.89 Rsun, Teff = 5500
K, [Fe/H] = 0.05; HATS-14: V = 13.8 mag, M* = 0.97 Msun, R* = 0.93 Rsun, Teff =
5350 K, [Fe/H] = 0.33) and both the planets orbit around them with a period of
roughly 3 days and a separation of roughly 0.04 au. However, even though they
are irradiated in a similar way, the physical characteristics of the two
planets are very different. HATS-13b, with a mass of Mp = 0.543 MJ and a radius
of Rp = 1.212 RJ, appears as an inflated planet, while HATS-14b, having a mass
of Mp = 1.071 MJ and a radius of Rp = 1.039 RJ, is only slightly larger in
radius than Jupiter.Comment: 13 pages, 7 figures, Submitted to Astronomy & Astrophysics. arXiv
admin note: text overlap with arXiv:1503.0006
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