J/ApJ/813/111 Differential photometry of the K dwarf HATS-7 (Bakos+, 2015)
HATS-7b: a hot super Neptune transiting a quiet K dwarf star.
Bakos G.A., Penev K., Bayliss D., Hartman J.D., Zhou G., Brahm R.,
Mancini L., de Val-Borro M., Bhatti W., Jordan A., Rabus M., Espinoza N.,
Csubry Z., Howard A.W., Fulton B.J., Buchhave L.A., Ciceri S., Henning T.,
Schmidt B., Isaacson H., Noyes R.W., Marcy G.W., Suc V., Howe A.R.,
Burrows A.S., Lazar J., Papp I., Sari P.
<Astrophys. J., 813, 111 (2015)>
=2015ApJ...813..111B 2015ApJ...813..111B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Photometry, ugriz
Keywords: stars: individual: HATS-7; techniques: photometric;
techniques: radial velocities; techniques: spectroscopic
Abstract:
We report the discovery by the HATSouth network of HATS-7b, a
transiting Super-Neptune with a mass of 0.120±0.012MJ, a radius of
0.563-0.034+0.046RJ, and an orbital period of 3.1853 days. The
host star is a moderately bright (V=13.340±0.010mag,
Ks=10.976±0.026mag) K dwarf star with a mass of
0.849±0.027M☉, a radius of 0.815-0.035+0.049R☉, and
a metallicity of [Fe/H]=+0.250±0.080. The star is photometrically
quiet to within the precision of the HATSouth measurements, has low RV
jitter, and shows no evidence for chromospheric activity in its
spectrum. HATS-7b is the second smallest radius planet discovered by a
wide-field ground-based transit survey, and one of only a handful of
Neptune-size planets with mass and radius determined to 10% precision.
Theoretical modeling of HATS-7b yields a hydrogen-helium fraction of
18±4% (rock-iron core and H2-He envelope), or 9±4% (ice core and
H2-He envelope), i.e., it has a composition broadly similar to that
of Uranus and Neptune, and very different from that of Saturn, which
has 75% of its mass in H2-He. Based on a sample of transiting
exoplanets with accurately (<20%) determined parameters, we establish
approximate power-law relations for the envelopes of the mass-density
distribution of exoplanets. HATS-7b, which, together with the recently
discovered HATS-8b, is one of the first two transiting super-Neptunes
discovered in the Southern sky, is a prime target for additional
follow-up observations with Southern hemisphere facilities to
characterize the atmospheres of Super-Neptunes (which we define as
objects with mass greater than that of Neptune, and smaller than
halfway between that of Neptune and Saturn, i.e.,
0.054MJ<Mp<0.18MJ).
Description:
The star HATS-7 (2MASS J13552567-2112276) was observed by the
Hungarian-made Automated Telescope Network-South (HATSouth) wide-field
telescope network between UT 2011 March 24 and UT 2011 August 19.
Observations were made from Las Campanas Observatory (LCO) in Chile,
the High Energy Stereoscopic System (HESS) site in Namibia, and Siding
Spring Observatory (SSO) in Australia.
Photometric follow-up observations of HATS-7 were performed using the
1-m telescopes in the Las Cumbres Observatory Global Telescope network
(LCOGT) and the GROND instrument on the MPG 2.2m telescope at La Silla
Observatory (LSO) in Chile; in 2014 Jun 12,16 and 2014 Jul 20.
Objects:
--------------------------------------------------------------
RA (ICRS) DE Designation(s) (Period)
--------------------------------------------------------------
13 55 25.67 -21 12 27.6 HATS-7b = HATS-7b (P=3.185315)
--------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 49 7969 Differential photometry of HATS-7
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See also:
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)
J/A+A/580/A63 : HATS-13b and HATS-14b light and RV curves (Mancini+, 2015)
J/AJ/150/49 : Photometry and spectroscopy of HATS-8 (Bayliss+, 2015)
J/AJ/148/29 : Spectroscopy & differential photom. of HATS-4 (Jordan+, 2014)
J/AJ/147/144 : Differential griz photometry of HATS-5 (Zhou+, 2014)
J/AJ/147/128 : HAT-P-44, HAT-P-45, and HAT-P-46 follow-up (Hartman+, 2014)
J/MNRAS/437/2831 : 4 transiting F-M binary systems (Zhou+, 2014)
J/AJ/146/113 : Differential griz photometry of HATS-3 (Bayliss+, 2013)
J/A+A/558/A55 : HATS-2b griz light curves (Mohler-Fischer+, 2013)
J/A+A/549/A134 : 4 new WASP transiting close-in giant planets (Hebrard+, 2013)
J/AJ/145/5 : Follow-up photometry of HATS-1 (Penev+, 2013)
J/AJ/144/139 : HAT-P-39, HAT-P-40, and HAT-P-41 follow-up (Hartman+, 2012)
J/A+A/546/A27 : Radial velocity and photometry for GJ3470 (Bonfils+, 2012)
J/other/Nat/486.375 : Stellar parameters of KOI stars (Buchhave+, 2012)
J/other/Nat/481.475 : RVs of Kepler-34b + Kepler-35b (Welsh+, 2012)
J/ApJ/728/138 : Follow-up photometry of HAT-P-26 (Hartman+, 2011)
J/ApJ/726/52 : HAT-P-18 and HAT-P-19 follow-up (Hartman+, 2011)
J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)
http://www.hatsouth.org/ : The HATSouth exoplanet survey home page
http://exoplanetarchive.ipac.caltech.edu/ : NASA exoplanet archive home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d BJD UTC Barycentric Julian date (1)
15- 22 F8.5 mag mag [-0.04/0.03] Differential magnitude in Filt (2)
24- 30 F7.5 mag e_mag [0.0006/0.02] Uncertainty in mag
32- 39 F8.5 mag Omag [-0.003/13.4]? Raw magnitude without
detrending (3)
41 A1 --- Filt [griz] Filter used in the observation (griz)
43- 49 A7 --- Inst Instrument/Telescope used in the observation (4)
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Note (1): Barycentric Julian Date is computed directly from the UTC time
without correction for leap seconds.
Note (2): The out-of-transit level has been subtracted. For the HATSouth
light curve (rows with "HS" in the Instrument column), these
magnitudes have been de-trended using the EPD and TFA procedures
prior to fitting a transit model to the light curve. Primarily as
a result of this detrending, but also due to blending from
neighbors, the apparent HATSouth transit depth is somewhat
shallower than that of the true depth in the Sloan r filter (the
apparent depth is 85% that of the true depth). For the follow-up
light curves (rows with an Instrument other than "HS") these
magnitudes have been detrended with the EPD procedure, carried
out simultaneously with the transit fit (the transit shape is
preserved in this process).
Note (3): Raw magnitude values without application of the EPD procedure.
These are only reported for the follow-up light curves.
Note (4): Instrument/Telescopes used as follows:
HS = HATSouth;
LCOGT1m = 1-m Las Cumbres Observatory Global Telescopes at SAAO and CTIO;
GROND = Gamma-Ray Burst Optical/Near-Infrared Detector on MPG/ESO 2.2m.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-Feb-2016