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HD 191939 revisited : New and refined planet mass determinations, and a new planet in the habitable zone

Orell-Miquel, J. ; Nowak, G. ; Murgas, F. ; Palle, E. ; Morello, G. ; Luque, R. ; Badenas-Agusti, M. ; Ribas, I. ; Lafarga, M. and Espinoza, N. , et al. (2023) In Astronomy and Astrophysics 669.
Abstract
HD 191939 (TOI-1339) is a nearby (d = 54 pc), bright (V = 9
mag), and inactive Sun-like star (G9 V) known to host a multi-planet
transiting system. Ground-based spectroscopic observations confirmed the
planetary nature of the three transiting sub-Neptunes (HD 191939 b, c,
and d) originally detected by TESS and were used to measure the masses
for planets b and c with 3σ precision. These previous observations also
reported the discovery of an additional Saturn-mass planet (HD 191939 e)
and evidence for a further, very long-period companion (HD 191939 f).
Here, we report the discovery of a new non-transiting planet in the
system and a refined mass determination of HD 191939 d. The new... (More)
HD 191939 (TOI-1339) is a nearby (d = 54 pc), bright (V = 9
mag), and inactive Sun-like star (G9 V) known to host a multi-planet
transiting system. Ground-based spectroscopic observations confirmed the
planetary nature of the three transiting sub-Neptunes (HD 191939 b, c,
and d) originally detected by TESS and were used to measure the masses
for planets b and c with 3σ precision. These previous observations also
reported the discovery of an additional Saturn-mass planet (HD 191939 e)
and evidence for a further, very long-period companion (HD 191939 f).
Here, we report the discovery of a new non-transiting planet in the
system and a refined mass determination of HD 191939 d. The new planet,
HD 191939 g, has a minimum mass of 13.5±2.0 M⊕ and a
period of about 280 days. This period places the planet within the
conservative habitable zone of the host star, and near a 1:3 resonance
with HD 191939 e. The compilation of 362 radial velocity measurements
with a baseline of 677 days from four different high-resolution
spectrographs also allowed us to refine the properties of the previously
known planets, including a 4.6σ mass determination for planet d, for which only a 2σ
upper limit had been set until now. We confirm the previously suspected
low density of HD 191939 d, which makes it an attractive target for
attempting atmospheric characterisation. Overall, the planetary system
consists of three sub-Neptunes interior to a Saturn-mass and a
Uranus-mass planet plus a high-mass long-period companion. This
particular configuration has no counterpart in the literature and makes
HD 191939 an exceptional multi-planet transiting system with an unusual
planet demographic worthy of future observation. (Less)
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type
Contribution to journal
publication status
published
subject
keywords
Planets and satellites: individual: HD 191939 d, Planets and satellites: individual: HD 191939 g, Stars: individual: HD 191939, Techniques: photometric, Techniques: radial velocities
in
Astronomy and Astrophysics
volume
669
article number
A40
pages
20 pages
publisher
EDP Sciences
external identifiers
  • scopus:85145774837
ISSN
0004-6361
DOI
10.1051/0004-6361/202244120
language
English
LU publication?
no
additional info
Publisher Copyright: © The Authors 2023.
id
1810dd61-1b6c-4847-8c61-84714e28df66
date added to LUP
2023-01-17 09:06:30
date last changed
2023-01-25 11:25:03
@article{1810dd61-1b6c-4847-8c61-84714e28df66,
  abstract     = {{HD 191939 (TOI-1339) is a nearby (<i>d</i> = 54 pc), bright (<i>V</i> = 9<br>
 mag), and inactive Sun-like star (G9 V) known to host a multi-planet <br>
transiting system. Ground-based spectroscopic observations confirmed the<br>
 planetary nature of the three transiting sub-Neptunes (HD 191939 b, c, <br>
and d) originally detected by TESS and were used to measure the masses <br>
for planets b and c with 3σ precision. These previous observations also <br>
reported the discovery of an additional Saturn-mass planet (HD 191939 e)<br>
 and evidence for a further, very long-period companion (HD 191939 f). <br>
Here, we report the discovery of a new non-transiting planet in the <br>
system and a refined mass determination of HD 191939 d. The new planet, <br>
HD 191939 g, has a minimum mass of 13.5±2.0 <i>M</i><sub>⊕</sub> and a <br>
period of about 280 days. This period places the planet within the <br>
conservative habitable zone of the host star, and near a 1:3 resonance <br>
with HD 191939 e. The compilation of 362 radial velocity measurements <br>
with a baseline of 677 days from four different high-resolution <br>
spectrographs also allowed us to refine the properties of the previously<br>
 known planets, including a 4.6<i>σ</i> mass determination for planet d, for which only a 2<i>σ</i><br>
 upper limit had been set until now. We confirm the previously suspected<br>
 low density of HD 191939 d, which makes it an attractive target for <br>
attempting atmospheric characterisation. Overall, the planetary system <br>
consists of three sub-Neptunes interior to a Saturn-mass and a <br>
Uranus-mass planet plus a high-mass long-period companion. This <br>
particular configuration has no counterpart in the literature and makes <br>
HD 191939 an exceptional multi-planet transiting system with an unusual <br>
planet demographic worthy of future observation.}},
  author       = {{Orell-Miquel, J. and Nowak, G. and Murgas, F. and Palle, E. and Morello, G. and Luque, R. and Badenas-Agusti, M. and Ribas, I. and Lafarga, M. and Espinoza, N. and Morales, J. C. and Zechmeister, M. and Alqasim, A. and Cochran, W. D. and Gandolfi, D. and Goffo, E. and Kabáth, P. and Korth, J. and Lam, K. W. F. and Livingston, J. and Muresan, A. and Persson, C. M. and Van Eylen, V.}},
  issn         = {{0004-6361}},
  keywords     = {{Planets and satellites: individual: HD 191939 d; Planets and satellites: individual: HD 191939 g; Stars: individual: HD 191939; Techniques: photometric; Techniques: radial velocities}},
  language     = {{eng}},
  month        = {{01}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{HD 191939 revisited : New and refined planet mass determinations, and a new planet in the habitable zone}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202244120}},
  doi          = {{10.1051/0004-6361/202244120}},
  volume       = {{669}},
  year         = {{2023}},
}