J/AJ/160/222 RVs and RI-photometry of HATS-37 and HATS-38 (Jordan+, 2020)
HATS-37Ab and HATS-38b: two transiting hot neptunes in the desert.
Jordan A., Bakos G.A., Bayliss D., Bento J., Bhatti W., Brahm R., Csubry Z.,
Espinoza N., Hartman J.D., Henning T., Mancini L., Penev K., Rabus M.,
Sarkis P., Suc V., de Val-Borro M., Zhou G., Butler R.P., Teske J.,
Crane J., Shectman S., Tan T.G., Thompson I., Wallace J.J., Lazar J.,
Papp I., Sari P.
<Astron. J., 160, 222 (2020)>
=2020AJ....160..222J 2020AJ....160..222J
ADC_Keywords: Exoplanets; Stars, double and multiple; Radial velocities;
Photometry, RI; Spectra, optical
Keywords: Exoplanets ; Hot Neptunes
Abstract:
We report the discovery of two transiting Neptunes by the HATSouth
survey. The planet HATS-37Ab has a mass of 0.099±0.042MJup
(31.5±13.4M⊕) and a radius of 0.606±0.016RJup, and is
on a P=4.3315day orbit around a V=12.266±0.030mag,
0.843-0.012+0.017M☉ star with a radius of
0.877-0.012+0.019R☉. We also present evidence that the star
HATS-37A has an unresolved stellar companion HATS-37B, with a
photometrically estimated mass of 0.654±0.033M☉. The planet
HATS-38b has a mass of 0.074±0.011MJup (23.5±3.5M⊕)
and a radius of 0.614±0.017RJup, and is on a P=4.3750day orbit
around a V=12.411±0.030mag, 0.890-0.012+0.016M☉ star with
a radius of 1.105±0.016 R☉. Both systems appear to be old,
with isochrone-based ages of 11.46-1.45+0.79Gyr, and
11.89±0.60Gyr, respectively. Both HATS-37Ab and HATS-38b lie in
the Neptune desert and are thus examples of a population with a low
occurrence rate. They are also among the lowest-mass planets found
from ground-based wide-field surveys to date.
Description:
The facilities include: the Chilean-Hungarian Automated Telescope
(CHAT) 0.7m telescope at Las Campanas Observatory, Chile; 1m
telescopes from the Las Cumbres Observatory (LCO) network; the 0.3m
Perth Exoplanet Survey Telescope in Australia (PEST); and the Swope 1m
telescope at Las Campanas Observatory in Chile. The HATSouth
observations of each system are summarized in Table 1.
The spectroscopic observations carried out to confirm and characterize
both of the transiting planet systems are summarized in Table 2. The
facilities used include Fiber-fed Extended Range Optical Spectrograph
(FEROS) on the Max Planck Gesellschaft (MPG) 2.2m, Coralie on the
Euler 1.2m, High Accuracy Radial velocity Planet Searcher (HARPS) on
the European Southern Observatory (ESO) 3.6m, Wide-Field Spectrograph
(WiFeS) on the Australian Nation University (ANU) 2.3m, and Planet
Finder Spectrograph (PFS) on the Magellan 6.5m.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 69 23 Summary of photometric observations
table2.dat 79 11 Summary of spectroscopy observations
table3.dat 67 41853 Light curve data for HATS-37 and HATS-38
table4.dat 63 47 Relative radial velocities and bisector spans for
HATS-37 and HATS-38
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See also:
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
J/A+A/428/1001 : Non-linear limb-darkening law for LTE modelsIII. (Claret,2004)
J/ApJ/710/1724 : Follow-up photometry for HAT-P-11 (Bakos+, 2010)
J/ApJ/728/138 : Follow-up photometry of HAT-P-26 (Hartman+, 2011)
J/A+A/546/A14 : Limb-darkening for CoRoT, Kepler, Spitzer (Claret+, 2012)
J/AJ/146/113 : Differential griz photometry of HATS-3 (Bayliss+, 2013)
J/A+A/552/A16 : Limb-darkening for CoRoT, Kepler, Spitzer. II. (Claret+, 2013)
J/A+A/558/A55 : HATS-2b griz light curves (Mohler-Fischer+, 2013)
J/AJ/145/5 : Follow-up photometry of HATS-1 (Penev+, 2013)
J/AJ/148/29 : Spectro. and differential photometry of HATS-4 (Jordan+,2014)
J/AJ/149/166 : Photometry and spectroscopy of HATS-6 (Hartman+, 2015)
J/AJ/152/108 : i filter photom. for HATS-25 through HATS-30 (Espinoza+, 2016)
J/AJ/152/88 : Spectroscopy & photometry of HATS-11 & HATS-12 (Rabus+, 2016)
J/A+A/618/A20 : Limb-darkening for TESS, Kepler, Corot, MOST (Claret, 2018)
J/AJ/155/255 : Radial velocity & activity measur. of HAT-P-11 (Yee+, 2018)
J/AJ/156/259 : Robo-AO detected close binaries in Gaia DR2 (Ziegler+, 2018)
J/AJ/157/55 : RVs and light curves for HATS-60-HATS-69 (Hartman+, 2019)
J/AJ/159/267 : Observations & radial velocity of HATS-71b (Bakos+, 2020)
http://pestobservatory.com/ : Perth Exoplanet Survey Telescope homepage
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- ID Star identification
9- 17 A9 --- Inst Instrument used (1)
19- 30 A12 --- Field Field covered (2)
32- 42 A11 --- Obs-b Beginning of observation, year, month and day
44- 51 A8 -- Obs-e End of the observation, year and month
53- 56 I4 --- Nobs [82/8718] Number of images
58- 61 I4 s Cad [104/1232] Imaging cadence (3)
63- 64 A2 --- Filt Filter used; Rc, i, i' or r
66- 69 F4.1 mmag rms [0.8/15.7] Residual from the best-fit model
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Note (1): For HATSouth data we list the HATSouth unit, CCD, and field
name from which the observations are taken. HS-1 and -2 are located at
Las Campanas Observatory in Chile, HS-3 and -4 are located at the High
Energy Spectroscopic Survey site in Namibia, and HS-5 and -6 are
located at Siding Spring Observatory in Australia. Each unit has four
CCDs.
Note (2): Each field corresponds to 1 of 838 fixed pointings used to
cover the full 4π celestial sphere. All data from a given HATSouth
field and CCD number are reduced together, while detrending through
external parameter decorrelation (EPD) is done independently for each
unique unit+CCD+field combination. For HATS-38 we also derived light
curves from short (30 s) focus frames that were taken by the HATSouth
instruments every ∼20 minutes. The Swope 1m light curve for HATS-37
covered a predicted secondary eclipse event.
Note (3): The median time between consecutive images rounded to the
nearest second. Due to factors such as weather, the day-night cycle,
and guiding and focus corrections the cadence is only approximately
uniform over short timescales.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- ID Star identification
9- 29 A21 --- Inst Instrument used
31- 41 A11 --- Obs-b Beginning of the observation, year, month and day
43- 53 A11 --- Obs-e End of the observation, year, month and day
55- 56 I2 --- Nobs [1/18] Number of spectra
58- 60 I3 10^3 R [3/115] Resolution
(Δλ/λ/1000)
62- 63 I2 --- S/Nmin [17/38]? Minimum Signal-to-Noise ratio near
5180Å
65- 66 I2 --- S/Nmax [20/72]? Maximum Signal-to-Noise ratio near
5180Å
68- 72 F5.3 km/s RVel [4.13/8.2]? Radial velocity (1)
74- 79 F6.1 m/s RVelprec [5.7/4000]? Precision for RVel (2)
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Note (1): For high-precision RV observations included in the orbit
determination this is the zeropoint RV from the best-fit orbit. For
other instruments it is the mean value. We only provide this quantity
when applicable.
Note (2): For high-precision RV observations included in the orbit
determination this is the scatter in the RV residuals from the
best-fit orbit (which may include astrophysical jitter), for other
instruments this is either an estimate of the precision (not including
jitter), or the measured standard deviation. We only provide this
quantity when applicable.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- ID Star identifier
9- 21 F13.5 d BJD [2455644/2458215] Barycentric Julian Date (1)
23- 30 F8.5 mag mag [-0.04/12.5] Observed magnitude in Filter (2)
32- 38 F7.5 mag e_mag [0.0004/0.03] Uncertainty in mag
40- 47 F8.5 mag Omag [-0.05879/12.0802]? Original magnitude in Filter (3)
49- 50 A2 --- Filt Filter used; r, Rc or i
52- 67 A16 --- Inst Instrument used (4)
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Note (1): Computed directly from the UTC time without correction for leap
seconds.
Note (2): The out-of-transit level has been subtracted. For
observations made with the HAT-South instruments these magnitudes have
been corrected for trends using the External Parameter Decorrelation
(EPD) and TFA procedures applied prior to fitting the transit model.
This procedure may lead to an artificial dilution in the transit
depths. The blend factors for the HATSouth light curves are listed in
Table 6. For observations made with follow-up instruments (anything
other than "HS" in the "Inst" column), the magnitudes have been
corrected for a quadratic trend in time, and for variations correlated
with up to three PSF shape parameters, fit simultaneously with the
transit.
Note (3): Raw magnitude values without correction for the quadratic trend in
time, or for trends correlated with the seeing. These are only
reported for the follow-up observations.
Note (4): Instruments as follows:
HS = HAT-South (32107 occurrences)
HS.focus = HAT-South photometry from focus frames (8718 occurrences)
LCO1m/CTIO/DomeC = 1m telescope, Las Cumbres Observatory, Dome C at CTIO
(226 occurrences)
LCO1m/SAAO/DomeB = 1m telescope, Las Cumbres Observatory, Dome B at SAAO
(83 occurrences)
LCO1m/SAAO/DomeC = 1m telescope, Las Cumbres Observatory, Dome C at SAAO
(82 occurrences)
Swope1m = Swope 1m telescope (161 occurrences)
CHAT0.7m = Chilean-Hungarian Automated Telescope 0.7m telescope
(363 occurrences)
PEST0.3m = 0.3 m Perth Exoplanet Survey Telescope in Australia
(113 occurrences)
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- ID Star identifier
9-21 F13.5 d BJD [2457505/2457891] Barycentric Julian Date; BJD-2450000
23-28 F6.2 m/s RVel [-43.4/50.3]? Radial velocity (1)
30-34 F5.2 m/s e_RVel [2.71/15.0]? Uncertainty in RVel (2)
36-42 F7.2 m/s BS [-130.4/125] Bisector span
44-48 F5.2 m/s e_BS [5/40.4] Uncertainty in BS
50-57 F8.6 --- Phase [0.108/0.917] Orbital phase
59-63 A5 --- Inst Instrument; FEROS, HARPS or PFS
--------------------------------------------------------------------------------
Note (1): The zero-point of these velocities is arbitrary. An overall offset
γrel fitted independently to the velocities from each
instrument has been subtracted.
Note (2): Internal errors excluding the component of astrophysical jitter
listed in Table 6.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 22-Jan-2021