J/AJ/158/45 TESS light curve & radial velocities for HD 1397 (Brahm+, 2019)
HD 1397b: a transiting warm giant planet orbiting a V=7.8 mag subgiant star
discovered by TESS.
Brahm R., Espinoza N., Jordan A., Henning T., Sarkis P., Jones M.I.,
Diaz M.R., Jenkins J.S., Vanzi L., Zapata A., Petrovich C., Kossakowski D.,
Rabus M., Rojas F., Torres P.
<Astron. J., 158, 45 (2019)>
=2019AJ....158...45B 2019AJ....158...45B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, bright ; Photometry ; Optical ; Radial velocities ;
Exoplanets
Keywords: planetary systems - planets and satellites: detection -
planets and satellites: gaseous planets
Abstract:
We report the discovery of a transiting planet first identified as a
candidate in Sector 1 of the Transiting Exoplanet Survey Satellite
(TESS), and then confirmed with precision radial velocities. HD 1397b
has a mass of MP=0.367-0.023+0.022 MJ, a radius of
RP=1.023-0.013+0.013 RJ, and orbits its bright host star
(V=7.8 mag) with an orbital period of 11.5366±0.0003 d on a
moderately eccentric orbit (e=0.216-0.026+0.027). With a mass of
M*=1.257-0.029+0.029 M☉, a radius of
R*=2.341-0.019+0.022 R☉, and an age of 4.46±0.25 Gyr,
the solar-metallicity host star has already departed from the main
sequence. We find evidence in the radial velocity measurements of a
secondary signal with a longer period. We attribute it to the rotational
modulation of stellar activity, but a long-term radial velocity
monitoring would be necessary to discard if this signal is produced by
a second planet in the system. The HD 1397 system is among the brightest
ones currently known to host a transiting planet, which will make it
possible to perform detailed follow-up observations in order to
characterize the properties of giant planets orbiting evolved stars.
Description:
Between 2018 July 25 and 2018 August 22, the TESS mission observed HD 1397
(TIC 394137592, TOI00120.01) with its Camera 3 during the monitoring of
the first TESS sector. Observations were performed with a cadence of
2 minutes. HD 1397 was also observed during the monitoring of the second
TESS sector. However, no two-minute cadence light curve was processed
by the SPOC pipeline. The reason for this could be related to the position
of the star in the TESS detector, because it was located just a few pixels
from the edge. Nonetheless, we extracted a light curve from the full-frame
images (FFIs) using tesseract (http://github.com/astrofelipe/tesseract)
(F. Rojas et al. 2019 in preparation).
We started the radial velocity follow-up of HD 1397 a couple of hours
after the first alerts of TESS Sector 1 were made public. We obtained two
spectra with the High Accuracy Radial Velocity Planet Searcher (HARPS)
spectrograph (Mayor et al. 2003Msngr.114...20M 2003Msngr.114...20M) installed at the ESO 3.6 m
telescope at La Silla Observatory on two consecutive nights. Additionally,
we obtained 35 spectra with the The Fiber Dual Echelle Optical Spectrograph
(FIDEOS; Vanzi et al. 2018MNRAS.477.5041V 2018MNRAS.477.5041V) installed at the 1 m telescope
on the same observatory. FIDEOS observations were obtained on six
consecutive nights. We then proceeded to perform an intensive radial
velocity monitoring of HD 1397 with the Fiber-fed Extended Range Optical
Spectrograph (FEROS) installed at the MPG 2.2 m telescope at La Silla
Observatory (Kaufer et al. 1999Msngr..95....8K 1999Msngr..95....8K). We obtained 88 spectra
on a time span of 80 nights.
Objects:
-----------------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------------
00 17 47.15 -66 21 32.1 HD 1397 = TIC 394137592
-----------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 37 1210 30 minutes cadence TESS light curve data for
HD 1397 obtained from the tesseract extraction
of the full-frame images (FFIs) of Sector 2
table4.dat 65 127 Relative radial velocities and bisector spans
for HD 1397
--------------------------------------------------------------------------------
See also:
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)
J/AJ/156/102 : The TESS Input Catalog and Candidate Target List
(Stassun+, 2018)
J/ApJS/239/2 : Simulated exoplanets from TESS list of targets (Barclay+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD Barycentric Julian Date
16- 23 F8.6 --- Flux [0.995117/1.001652] Extracted flux divided
by the median value
25- 32 F8.6 --- e_Flux [5.7e-05/5.8e-05] The 1σ error in Flux
34- 37 A4 --- Inst Instrument used (TESS)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.8 d BJD Barycentric Julian Date
18- 24 F7.4 km/s RV [30.6421/30.8181] Radial velocity
26- 31 F6.4 km/s e_RV [0.002/0.014] Uncertainty in RV
33- 38 F6.3 km/s BIS [-0.044/0.051] Bisector span
40- 44 F5.3 km/s e_BIS [0.002/0.014] Uncertainty in BIS
46- 51 F6.4 --- S [0.1789/0.2323]? S-index
53- 58 F6.4 --- e_S [0.0015/0.0044]? Uncertainty in S
60- 65 A6 --- Inst Instrument used (FEROS, FIDEOS or HARPS)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 10-Sep-2019