J/AJ/152/127 Sloan i follow-up light curves of HATS-18 (Penev+, 2016)
HATS-18b: an extreme short-period massive transiting planet spinning up its
star.
Penev K., Hartman J.D., Bakos G.A., Ciceri S., Brahm R., Bayliss D.,
Bento J., Jordan A., Csubry Z., Bhatti W., de Val-Borro M., Espinoza N.,
Zhou G., Mancini L., Rabus M., Suc V., Henning T., Schmidt B., Noyes R.W.,
Lazar J., Papp I., Sari P.
<Astron. J., 152, 127-127 (2016)>
=2016AJ....152..127P 2016AJ....152..127P (SIMBAD/NED BibCode)
ADC_Keywords: Planets ; Stars, double and multiple ; Photometry, ugriz ;
Radial velocities
Keywords: planetary systems - planets and satellites: detection -
planets and satellites: gaseous planets - stars: individual: HATS-18 -
stars: rotation - techniques: photometric
Abstract:
We report the discovery by the HATSouth network of HATS-18b: a
1.980±0.077MJ, 1.337-0.049+0.102RJ planet in a 0.8378day
orbit, around a solar analog star (mass 1.037±0.047M☉ and
radius 1.020-0.031+0.057R☉) with V=14.067±0.040mag. 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≲log10(Q*/k2)≲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.
Description:
The star HATS-18 was observed by HATSouth instruments between UT 2011
April 18 and UT 2013 July 21 using the HS-2, HS-4, and HS-6 units at
the Las Campanas Observatory in Chile, the High Energy Spectroscopic
Survey (H.E.S.S.) site in Namibia, and Siding Spring Observatory (SSO)
in Australia, respectively. A total of 5372, 3758, and 4008 images of
HATS-18 were obtained with HS-2, HS-4, and HS-6, respectively. The
observations were obtained through a Sloan r filter with an exposure
time of 240s.
We obtained follow-up light curves of HATS-18 using the Las Cumbres
Observatory Global Telescope (LCOGT) 1m telescope network. An ingress
was observed on UT 2015 July 18 with the SBIG camera and a Sloan i
filter on the 1m at the South African Astronomical Observatory (SAAO).
A total of 33 images were collected at a median cadence of 201s. A
full transit was observed on UT 2016 January 22 with the sinistro
camera and a Sloan i filter on the 1m at Cerro Tololo Inter-American
Observatory. A total of 61 images were collected at a median cadence
of 219s. For the record, we also note that a full transit was observed
on UT 2016 January 3 with the SBIG camera on the 1m at SAAO; however,
due to tracking and weather problems, we were unable to extract
high-precision photometry from these images, and therefore do not
include these data in our analysis. The data are available in Table1.
Spectroscopic follow-up observations of HATS-18 were carried out with
WiFeS on the Australian National University (ANU) 2.3m telescope and
with the Fiber-fed Extended Range Optical Spectrograph (FEROS) on the
MPG 2.2m. A total of three spectra were obtained with WiFeS between UT
2015 February 28 and UT 2015 March 2, two at a resolution of
R=Δλ/λ=7000, and one at R=3000. We obtained six
R=48000 spectra with FEROS between UT 2015 June 12 and UT 2015 June
20. The data are provided in Table2.
Objects:
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RA (ICRS) DE Designation(s) (Period)
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11 35 49.78 -29 09 21.6 HATS-18 = GSC 06664-00410 (P=0.83784340)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 13232 Differential photometry of HATS-18
table2.dat 55 6 Relative radial velocities and bisector span
measurements of HATS-18
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See also:
J/AJ/148/29 : Spectroscopy and photometry of HATS-4 (Jordan+, 2014)
J/AJ/146/113 : Differential griz photometry of HATS-3 (Bayliss+, 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/ApJ/710/1724 : Follow-up photometry for HAT-P-11 (Bakos+, 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD UTC Barycentric Julian date (BJD-2400000) (1)
15- 22 F8.5 mag Dmag [-0.073/0.0667] Δ magnitude observed in
filter (2)
24- 30 F7.5 mag e_Dmag [0.0016/0.022] Uncertainty in Dmag
32- 39 F8.5 mag omag [-0.009/13.8]? Raw, observed magnitude (3)
41 A1 --- Flt [ir] Filter used in the observation (Sloan i, or
Sloan r)
43- 58 A16 --- Inst Instrument used in the observation (HS,
LCOGT1m/SBIG, or LCOGT1m/sinistro) (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
detrended using the External Parameter Decorrelation (EPD; Bakos et al.
2010, Cat. J/ApJ/710/1724) and the Trend Filtering Algorithm (TFA; Kovacs
et al. 2005MNRAS.356..557K 2005MNRAS.356..557K) procedures prior to fitting a transit model
to the light curve. We apply the TFA in signal-reconstruction mode so as to
preserve the transit 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.
Note (3): Raw magnitude values without application of the EPD procedure. This is
only reported for the follow-up light curves.
Note (4): The instruments used are defined as follows:
HS = HATSouth telescope;
LCOGT1m/SBIG = Las Cumbres Observatory Global Telescope (LCOGT) 1m
telescope + Siding Spring Observatory (SSO)/SBIG camera;
LCOGT1m/sinistro = LCOGT 1m telescope + Cerro Tololo Inter-American
Observatory (CTIO)/sinistro camera.
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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 Barycentric Julian Date (1)
15- 21 F7.2 m/s RV [-420.1/425] Relative radial velocity (2)
23- 27 F5.2 m/s e_RV [15/21] Uncertainty in RV (3)
29- 34 F6.2 m/s BS [-24/149] Bisector span
36- 40 F5.2 m/s e_BS [16/24] Uncertainty in BS
42- 49 F8.6 --- Phase [0/1] Phase
51- 55 A5 --- Inst Instrument (FEROS=Fiber-fed Extended Range
Optical Spectrograph/MPG 2.2m)
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Note (1): Barycentric Julian Date is computed directly from the UTC time without
correction for leap seconds.
Note (2): Relative radial velocity, with γRV subtracted (See Table3).
Note (3): Internal errors excluding the component of astrophysical/instrumental
jitter considered in Section 3 in the paper.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 02-Feb-2017