J/MNRAS/529/3323 HD 77946 RV curves (Palethorpe+, 2024)
Confronting compositional confusion through the characterization of the
sub-Neptune orbiting HD 77946.
Palethorpe L., Anna John A., Mortier A., Davoult J., Wilson T. G., Rice K.,
Cameron A. C., Alibert Y., Buchhave L., Malavolta L., Cadman J.,
Lopez-Morales M., Dumusque X., Silva A. M., Quinn S. N., Van Eylen V.,
Vissapragada S., Affer L., Charbonneau D., Cosentino R., Ghedina A.,
Haywood R. D., Latham D. W., Lienhard F., Martinez Fiorenzano A. F.,
Pedani M., Pepe F., Pinamonti M., Sozzetti A., Stalport M., Udry S.,
Vanderburg A.
<Mon. Not. R. Astron. Soc., 529, 3323-3341>
=2024MNRAS.529.3323P 2024MNRAS.529.3323P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities ;
Optical
Keywords: techniques: photometric - techniques: radial velocities -
techniques: spectroscopic - planets and satellites: composition -
planets and satellites: fundamental parameters -
stars: individual (HD 77946)
Abstract:
We report on the detailed characterization of the HD 77946 planetary
system. HD 77946 is an F5 (M*=1.17M☉, R*=1.31R☉) star,
which hosts a transiting planet recently discovered by NASA's
Transiting Exoplanet Survey Satellite (TESS), classified as TOI-1778
b. Using TESS photometry, high-resolution spectroscopic data from
HARPS-N, and photometry from CHEOPS, we measure the radius and mass
from the transit and radial velocity observations, and find that the
planet, HD 77946 b, orbits with period
Pb=6.527282-0.000020+0.000015d, has a mass of
Mb=8.38±1.32M⊕, and a radius of
Rb=2.705-0.081+0.086R⊕. From the combination of mass and
radius measurements, and the stellar chemical composition, the planet
properties suggest that HD 77946 b is a sub-Neptune with a ∼1 per cent
H/He atmosphere. However, a degeneracy still exists between
water-world and silicate/iron-hydrogen models, and even though
interior structure modelling of this planet favours a sub-Neptune with
a H/He layer that makes up a significant fraction of its radius, a
water-world composition cannot be ruled out, as with Teq=
1248+40-38K, water may be in a supercritical state. The
characterization of HD 77946 b, adding to the small sample of
well-characterized sub-Neptunes, is an important step forwards on our
journey to understanding planetary formation and evolution pathways.
Furthermore, HD 77946 b has one of the highest transmission
spectroscopic metrics for small planets orbiting hot stars, thus
transmission spectroscopy of this key planet could prove vital for
constraining the compositional confusion that currently surrounds
small exoplanets.
Description:
Table1 contains the DRS reduced radial velocities and activity
indicators for HD 77946 obtained by HARPS-N. Table2 contains the
s-BART reduced radial velocities for HD 77946 obtained by HARPS-N.
Objects:
------------------------------------------------
RA (2000) DE Designation(s)
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09 07 06.73 +46 40 21.3 HD 77946 = TOI-1778
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 93 102 HARPS-N RV DRS reduced data
table2.dat 28 102 HARPS-N RV s-BART reduced data
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 F15.7 d BJD Barycentric Julian date
17- 24 F8.2 m/s RV Radial velocity
26- 29 F4.2 m/s e_RV Error in radial velocity
31- 36 F6.3 m/s BIS Bisector inverse span
38- 41 F4.2 m/s e_BIS Error in bisector inverse span
43- 49 F7.5 km/s FWHM Full-width-at-half-maximum of the CCF
51- 57 F7.5 km/s e_FWHM Error in Full-width-at-half-maximum of the CCF
59- 66 F8.6 --- Halpha Halpha index
68- 75 F8.6 --- e_Halpha Error in Halpha index
77- 84 F8.5 --- logRHK RHK activity index
86- 93 F8.6 --- e_logRHK Error in RHK activity index
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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- 14 F14.6 d BJD Barycentric Julian date
16- 23 F8.2 m/s RV Radial velocity
25- 28 F4.2 m/s e_RV Error in radial velocity
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Acknowledgements:
Larissa Palethorpe, larissa.palethorpe(at)ed.ac.uk
(End) Patricia Vannier [CDS] 03-Jun-2024