J/AJ/157/31 Differential photometry & radial velocities of HATS-70 (Zhou+, 2019)
HATS-70b: a 13 MJ brown dwarf transiting an A star.
Zhou G., Bakos G.A., Bayliss D., Bento J., Bhatti W., Brahm R., Csubry Z.,
Espinoza N., Hartman J.D., Henning T., Jordan A., Mancini L., Penev K.,
Rabus M., Sarkis P., Suc V., de Val-Borro M., Rodriguez J.E., Osip D.,
Kedziora-Chudczer L., Bailey J., Tinney C.G., Durkan S., Lazar J., Papp I.,
Sari P.
<Astron. J., 157, 31 (2019)>
=2019AJ....157...31Z 2019AJ....157...31Z
ADC_Keywords: Stars, A-type ; Photometry, ugriz ; Photometry, RI ;
Photometry, infrared ; Radial velocities ; Exoplanets
Keywords: stars: individual (HATS-70) - techniques: spectroscopic -
techniques: photometric
Abstract:
We report the discovery of HATS-70b, a transiting brown dwarf at the
deuterium burning limit. HATS-70b has a mass of
Mp=12.9-1.6+1.8 MJup and a radius of
Rp=1.384-0.074+0.079 RJup, residing in a close-in orbit with a
period of 1.89 days. The host star is a M*=1.78±0.12 M☉ A star
rotating at vsinI*=40.61-0.35+0.32 km/s, 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
λ=8.9-4.5+5.6o. 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.
Description:
The transits of HATS-70b were first identified by the HATSouth network
(Bakos et al. 2013PASP..125..154B 2013PASP..125..154B). To provide continuous coverage of large
fields of the sky, HATSouth operates a network of telescopes across the
Southern hemisphere, at Las Campanas Observatory in Chile, at the High
Energy Spectroscopic Survey site in Namibia, and at Siding Spring
Observatory (SSO) in Australia. A series of photometric follow-up
observations were obtained for the transits of HATS-70b. These observations
were gathered over the course of 5 years, covering photometric bands ranging
from g in the blue to Ks in the near-infrared. The egress of HATS-70b was
captured on 2013 Oct 26 with the 0.9 m SMARTS Telescope at Cerro Tololo
Inter-American Observatory. A full I band transit on 2014 Mar 13 was
observed with the Danish Faint Object Spectrograph and Camera on the Danish
1.54 m (DK 1.54 m) telescope at La Silla, Chile. A partial transit was
obtained with the IRIS2 infrared camera on the Anglo-Australian Telescope
at SSO, Australia, on 2016 Feb 16. The observations were obtained in the
Ks band and were reduced as per the procedure described in Zhou et al.
(2014MNRAS.445.2746Z 2014MNRAS.445.2746Z). The 1 m Swope telescope, located at Las Campanas
Observatory, was used on 2016 Feb 19 to obtain a g full transit using its
e2v CCD camera. An i band egress of HATS-70b was observed with the 0.7 m
Chilean-Hungarian Automated Telescope (CHAT) on 2018 Jan 14. CHAT is a
dedicated transit-follow-up telescope located at Las Campanas Observatory,
and makes use of a 2Kx2K back-illuminated CCD yielding a pixel scale of
0.6"/pixel over a field of view of 21'x21'. Observations from the Las
Cumbres Observatory (LCO; Brown et al. 2013PASP..125.1031B 2013PASP..125.1031B) 1 m telescope
at the South African Astronomical Observatory on 2018 Jan 16 covered
the full transit in i band with the Sinistro camera.
Seven observations were obtained with the CORALIE spectrograph
(Queloz et al. 2001Msngr.105....1Q 2001Msngr.105....1Q) on the Euler 1.2 m telescope at
La Silla Observatory, Chile. Spectra from CORALIE covers the range of
3900-6800 Å at a resolution of λ/Δλ=R=60000. Our
observations were obtained with integration times of 1800-3600 s, yielding
a signal-to-noise ratio of ∼20 per resolution element. An additional
12 observations were obtained with FEROS (Kaufer & Pasquini
1998SPIE.3355..844K 1998SPIE.3355..844K) on the MPG 2.2 m telescope at La Silla. FEROS is
a fiber fed spectrograph with spectral resolution of R=48000 over the
wavelength range of 3500-9200 Å. The radial velocities from CORALIE
and FEROS are listed in Table 4.
Objects:
------------------------------------------------------
RA (ICRS) DE Designation(s)
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07 16 25.09 -31 14 39.9 HATS-70 = TYC 7103-114-1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 92 13270 Differential photometry of HATS-70
table4.dat 37 20 Relative radial velocities of HATS-70
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See also:
J/AJ/146/113 : Differential griz photometry of HATS-3 (Bayliss+, 2013)
J/AJ/147/144 : Differential griz photometry of HATS-5 (Zhou+, 2014)
J/AJ/148/29 : Spectroscopy and differential photometry of HATS-4
(Jordan+, 2014)
J/AJ/149/166 : Photometry and spectroscopy of HATS-6 (Hartman+, 2015)
J/AJ/150/33 : Photometry and spectroscopy of HATS-9 and HATS-10
(Brahm+, 2015)
J/AJ/150/49 : Photometry and spectroscopy of HATS-8 (Bayliss+, 2015)
J/ApJ/813/111 : Differential photometry of the K dwarf HATS-7 (Bakos+, 2015)
J/AJ/151/89 : Spectroscopy and photometry of HATS-17 (Brahm+, 2016)
J/AJ/152/88 : Spectroscopy and photometry of HATS-11 and HATS-12
(Rabus+, 2016)
J/AJ/152/161 : Photometry for HATS-31 through HATS-35 (de Val-Borro+, 2016)
J/AJ/155/112 : Radial velocities + light curves for HATS-43-HATS-46
(Brahm+, 2018)
J/AJ/156/216 : Differential photometry + RVs of HATS-59 (Sarkis+, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 18 F18.10 d BJD Barycentric Julian Date
20- 37 F18.15 mag Rawmag [-0.0553642278526/14.84648] Raw magnitude or
differential magnitude in Filter
39- 57 F19.15 mag EPDmag [-15.2769/12.77532]? Detrended EPD magnitude
in Filter (1)
59- 69 F11.8 mag TFAmag [0.0009/12.69687]? Detrended TFA magnitude
in Filter (1)
71- 80 F10.8 mag sigma [0.0009/0.01204]? Magnitude uncertainty
82- 89 A8 --- Inst Instrument used
91- 92 A2 --- Filter Filter used (g, i, R, Rc, I or Ks)
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Note (1): The detrending and potential blending may cause the HATSouth transit
to be shallower than the true transit in the External Parameter Decorrelation
(EPD) and Trend Filtering Algorithm (TFA) light curves. This is accounted for
in the global modeling by the inclusion of a dilution factor. Follow-up light
curves have been treated with EPD simultaneous to the transit fitting.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 18 F18.10 d BJD Barycentric Julian Date (UTC)
20- 24 I5 m/s RV [32997/43412] Radial velocity
26- 29 I4 m/s e_RV [32/2224] Uncertainty in RV (1)
31- 37 A7 --- Inst Instrument
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Note (1): Internal errors excluding the component of astrophysical/instrumental
jitter considered in Section 3.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 13-May-2019