Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

The HD 93963 A transiting system: A 1.04 d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS

Serrano, L. M. ; Mustill, A. J. LU orcid ; Davies, M. B. LU and Walton, N. (2022) In Astronomy and Astrophysics 667.
Abstract
We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (M* = 1.109 ± 0.043M, R* = 1.043 ± 0.009 R)
in a visual binary system. We combined TESS and CHEOPS space-borne
photometry with MuSCAT 2 ground-based photometry, ‘Alopeke and PHARO
high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and
SOPHIE radial velocity measurements. We validated and spectroscopically
confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with
an orbital period of Pc ≈ 3.65 d that was reported to
be a TESS object of interest (TOI) shortly after the release of Sector
... (More)
We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (M* = 1.109 ± 0.043M, R* = 1.043 ± 0.009 R)
in a visual binary system. We combined TESS and CHEOPS space-borne
photometry with MuSCAT 2 ground-based photometry, ‘Alopeke and PHARO
high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and
SOPHIE radial velocity measurements. We validated and spectroscopically
confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with
an orbital period of Pc ≈ 3.65 d that was reported to
be a TESS object of interest (TOI) shortly after the release of Sector
22 data. HD 93963 A c has amass of Mc = 19.2 ± 4.1 M and a radius of Rc = 3.228 ± 0.059 R, implying a mean density of ρc = 3.1 ± 0.7 g cm-3.
The inner object, HD 93963 A b, is a validated 1.04 d ultra-short
period (USP) transiting super-Earth that we discovered in the TESS light
curve and that was not listed as a TOI, owing to the low significance
of its signal (TESS signal-to-noise ratio ≈6.7, TESS + CHEOPS combined
transit depth Db = 141.5−8.3+8.5
ppm). We intensively monitored the star with CHEOPS by performing nine
transit observations to confirm the presence of the inner planet and
validate the system. HD 93963 A b is the first small (Rb = 1.35 ± 0.042 R)
USP planet discovered and validated by TESS and CHEOPS. Unlike planet
c, HD 93963 Ab is not significantly detected in our radial velocities (Mb = 7.8 ± 3.2 M).
The two planets are on either side of the radius valley, implying that
they could have undergone completely different evolution processes. We
also discovered a linear trend in our Doppler measurements, suggesting
the possible presence of a long-period outer planet. With a V-band
magnitude of 9.2, HD 93963 A is among the brightest stars known to host
a USP planet, making it one of the most favourable targets for precise
mass measurement via Doppler spectroscopy and an important laboratory to
test formation, evolution, and migration models of planetary systems
hosting ultra-short period planets. (Less)
Please use this url to cite or link to this publication:
author
; ; and
author collaboration
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
planets and satellites: detection, planets and satellites: fundamental parameters, instrumentation: photometers, instrumentation: spectrographs, methods: data analysis, Astrophysics - Earth and Planetary Astrophysics
in
Astronomy and Astrophysics
volume
667
article number
A1
pages
25 pages
publisher
EDP Sciences
external identifiers
  • scopus:85148460884
ISSN
1432-0746
DOI
10.1051/0004-6361/202243093
language
English
LU publication?
yes
id
a7779c72-670d-4188-8570-b1ad6f7d4cec
alternative location
https://arxiv.org/abs/2207.13920
date added to LUP
2022-11-16 15:58:27
date last changed
2023-05-26 04:03:25
@article{a7779c72-670d-4188-8570-b1ad6f7d4cec,
  abstract     = {{We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (<i>M</i><sub>*</sub> = 1.109 ± 0.043<i>M</i><sub>⊙</sub>, <i>R</i><sub><i>*</i></sub> = 1.043 ± 0.009 <i>R</i><sub>⊙</sub>)<br>
 in a visual binary system. We combined TESS and CHEOPS space-borne <br>
photometry with MuSCAT 2 ground-based photometry, ‘Alopeke and PHARO <br>
high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and <br>
SOPHIE radial velocity measurements. We validated and spectroscopically <br>
confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with <br>
an orbital period of <i>P</i><sub>c</sub> ≈ 3.65 d that was reported to <br>
be a TESS object of interest (TOI) shortly after the release of Sector <br>
22 data. HD 93963 A c has amass of <i>M</i><sub>c</sub> = 19.2 ± 4.1 <i>M</i><sub>⊕</sub> and a radius of <i>R</i><sub>c</sub> = 3.228 ± 0.059 <i>R</i><sub>⊕</sub>, implying a mean density of <i>ρ</i><sub><i>c</i></sub> = 3.1 ± 0.7 g cm<sup>-3</sup>.<br>
 The inner object, HD 93963 A b, is a validated 1.04 d ultra-short <br>
period (USP) transiting super-Earth that we discovered in the TESS light<br>
 curve and that was not listed as a TOI, owing to the low significance <br>
of its signal (TESS signal-to-noise ratio ≈6.7, TESS + CHEOPS combined <br>
transit depth <i>D</i><sub>b</sub> = 141.5<sub>−8.3</sub><sup>+8.5</sup><br>
 ppm). We intensively monitored the star with CHEOPS by performing nine <br>
transit observations to confirm the presence of the inner planet and <br>
validate the system. HD 93963 A b is the first small (<i>R</i><sub>b</sub> = 1.35 ± 0.042 <i>R</i><sub>⊕</sub>)<br>
 USP planet discovered and validated by TESS and CHEOPS. Unlike planet <br>
c, HD 93963 Ab is not significantly detected in our radial velocities (<i>M</i><sub>b</sub> = 7.8 ± 3.2 <i>M</i><sub>⊕</sub>).<br>
 The two planets are on either side of the radius valley, implying that <br>
they could have undergone completely different evolution processes. We <br>
also discovered a linear trend in our Doppler measurements, suggesting <br>
the possible presence of a long-period outer planet. With a <i>V</i>-band<br>
 magnitude of 9.2, HD 93963 A is among the brightest stars known to host<br>
 a USP planet, making it one of the most favourable targets for precise <br>
mass measurement via Doppler spectroscopy and an important laboratory to<br>
 test formation, evolution, and migration models of planetary systems <br>
hosting ultra-short period planets.}},
  author       = {{Serrano, L. M. and Mustill, A. J. and Davies, M. B. and Walton, N.}},
  issn         = {{1432-0746}},
  keywords     = {{planets and satellites: detection; planets and satellites: fundamental parameters; instrumentation: photometers; instrumentation: spectrographs; methods: data analysis; Astrophysics - Earth and Planetary Astrophysics}},
  language     = {{eng}},
  month        = {{11}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{The HD 93963 A transiting system: A 1.04 d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202243093}},
  doi          = {{10.1051/0004-6361/202243093}},
  volume       = {{667}},
  year         = {{2022}},
}