J/ApJ/786/2 Spitzer photometric time series of HD 97658 (Van Grootel+, 2014)
Transit confirmation and improved stellar and planet parameters for
the super-Earth HD 97658 b and its host star.
Van Grootel V., Gillon M., Valencia D., Madhusudhan N., Dragomir D.,
Howe A.R., Burrows A.S., Demory B.-O., Deming D., Ehrenreich D., Lovis C.,
Mayor M., Pepe F., Queloz D., Scuflaire R., Seager S., Segransan D.,
Udry S.
<Astrophys. J., 786, 2 (2014)>
=2014ApJ...786....2V 2014ApJ...786....2V (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Photometry, infrared ;
Binaries, eclipsing
Keywords: binaries: eclipsing - planetary systems -
stars: individual: HD 97658 - techniques: photometric -
techniques: radial velocities
Abstract:
Super-Earths transiting nearby bright stars are key objects that
simultaneously allow for accurate measurements of both their mass and
radius, providing essential constraints on their internal composition.
We present here the confirmation, based on Spitzer transit
observations, that the super-Earth HD 97658 b transits its host star.
HD 97658 is a low-mass (M*=0.77±0.05 M☉) K1 dwarf, as
determined from the Hipparcos parallax and stellar evolution modeling.
To constrain the planet parameters, we carry out Bayesian global
analyses of Keck-High Resolution Echelle Spectrometer (Keck-HIRES)
radial velocities and Microvariability and Oscillations of STars
(MOST) and Spitzer photometry. HD 97658 b is a massive
(Mp=7.55-0.79+0.83 M{earth}) and large
(Rp=2.2470.095+0.098 R{earth} at 4.5 µm) super-Earth. We
investigate the possible internal compositions for HD 97658 b. Our
results indicate a large rocky component, of at least 60% by mass, and
very little H-He components, at most 2% by mass. We also discuss how
future asteroseismic observations can improve the knowledge of the
HD 97658 system, in particular by constraining its age. Orbiting a
bright host star, HD 97658 b will be a key target for upcoming space
missions such as the Transiting Exoplanet Survey Satellite (TESS), the
Characterizing Exoplanet Satellite (CHEOPS), the Planetary Transits
and Oscillations of stars (PLATO), and the James Webb Space Telescope
to characterize thoroughly its structure and atmosphere.
Description:
We monitored HD 97658 with Spitzer's IRAC camera on 2013 August 10
from 13:01:00 to 18:27:00 UT, corresponding to a transit window as
computed from the MOST transit ephemeris (Dragomir et al.
2013, J/ApJ/772/L2). These Spitzer data were acquired in the context
of the Cycle 9 program 90072 (PI: M. Gillon) dedicated to the search
for the transits of RV-detected low-mass planets. They consist of 2320
sets of 64 individual subarray images obtained at 4.5 µm with an
integration time of 0.08 s. They are available on the Spitzer Heritage
Archive database under the form of 2320 Basic Calibrated Data files
calibrated by the standard Spitzer reduction pipeline (version S19.1.0).
Objects:
-----------------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------------
11 14 33.16 +25 42 37.4 HD 97658 b = HD 97658b
11 14 33.16 +25 42 37.4 HD 97658 = HIP 54906
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 2320 Spitzer photometric time series of HD 97658,
as used by our MCMC algorithm
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See also:
J/ApJ/759/L41 : New radial velocities of HD 97658 (Dragomir+, 2012)
J/ApJ/772/L2 : Keck/HIRES radial velocities for HD 97658 (Dragomir+, 2013)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 F15.10 d BJD Barycentric Julian Date; UTC (BJD-2450000)
17- 26 F10.8 --- Flux Normalized Spitzer/IRAC 4.5 micron flux
28- 41 E14.8 --- e_Flux Error in Flux
43- 53 F11.8 pix dX Spitzer X pixel coordinate
55- 65 F11.8 pix dY Spitzer Y pixel coordinate
67- 72 F6.4 pix FWHM FWHM of source
74- 83 F10.8 pix FWHMX X component of FWHM
85- 94 F10.8 pix FWHMY Y component of FWHM
96-104 F9.6 --- Sky Sky brightness in electrons
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 20-Jul-2017