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Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf

Kawauchi, K. ; Murgas, F. ; Palle, E. ; Narita, N. ; Fukui, A. ; Hirano, T. ; Parviainen, H. ; Ishikawa, H. T. ; Watanabe, N. and Esparaza-Borges, E. , et al. (2022) In Astronomy and Astrophysics 666.
Abstract

Context. The NASA space telescope TESS is currently in the
extended mission of its all-sky search for new transiting planets. Of
the thousands of candidates that TESS is expected to deliver, transiting
planets orbiting nearby M dwarfs are particularly interesting targets
since they provide a great opportunity to characterize their atmospheres
by transmission spectroscopy.


Aims. We aim to validate and characterize the new sub-Neptune-sized planet candidate TOI-2136.01 orbiting a nearby M dwarf (d = 33.36 ± 0.02pc, Teff = 3373 ± 108 K) with an orbital period of 7.852 days.


Methods. We use TESS data, ground-based multicolor photometry,
and... (More)

Context. The NASA space telescope TESS is currently in the
extended mission of its all-sky search for new transiting planets. Of
the thousands of candidates that TESS is expected to deliver, transiting
planets orbiting nearby M dwarfs are particularly interesting targets
since they provide a great opportunity to characterize their atmospheres
by transmission spectroscopy.


Aims. We aim to validate and characterize the new sub-Neptune-sized planet candidate TOI-2136.01 orbiting a nearby M dwarf (d = 33.36 ± 0.02pc, Teff = 3373 ± 108 K) with an orbital period of 7.852 days.


Methods. We use TESS data, ground-based multicolor photometry,
and radial velocity measurements with the InfraRed Doppler (IRD)
instrument on the Subaru Telescope to validate the planetary nature of
TOI-2136.01, and estimate the stellar and planetary parameters. We also
conduct high-resolution transmission spectroscopy to search for helium
in its atmosphere.


Results. We confirm that TOI-2136.01 (now named TOI-2136b) is a bona fide planet with a planetary radius of Rp = 2.20 ± 0.07R⊕ and a mass of Mp = 4.7−2.6+3.1 M⊕.
We also search for helium 10830 Å absorption lines and place an upper
limit on the equivalent width of <7.8 mÅ and on the absorption signal
of <1.44% with 95% confidence.


Conclusions. TOI-2136b is a sub-Neptune transiting a nearby and bright star (J = 10.8 mag), and is a potentially hycean planet, which is a new class of habitable planets with large oceans under a H2-rich
atmosphere, making it an excellent target for atmospheric studies to
understand the formation, evolution, and habitability of the small
planets.

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publishing date
type
Contribution to journal
publication status
published
keywords
Planets and satellites: atmospheres, Planets and satellites: detection, Planets and satellites: individual: TOI-2136b, techniques: photometric, Techniques: radial velocities
in
Astronomy and Astrophysics
volume
666
article number
A4
pages
19 pages
publisher
EDP Sciences
external identifiers
  • scopus:85139879086
ISSN
0004-6361
DOI
10.1051/0004-6361/202243381
language
English
LU publication?
no
additional info
Publisher Copyright: ©
id
77546d1e-9dec-4359-b61e-f616f77fed60
date added to LUP
2023-01-17 09:11:04
date last changed
2023-02-21 09:36:09
@article{77546d1e-9dec-4359-b61e-f616f77fed60,
  abstract     = {{<p><i>Context.</i> The NASA space telescope TESS is currently in the <br>
extended mission of its all-sky search for new transiting planets. Of <br>
the thousands of candidates that TESS is expected to deliver, transiting<br>
 planets orbiting nearby M dwarfs are particularly interesting targets <br>
since they provide a great opportunity to characterize their atmospheres<br>
 by transmission spectroscopy.</p><br>
<p><i>Aims.</i> We aim to validate and characterize the new sub-Neptune-sized planet candidate TOI-2136.01 orbiting a nearby M dwarf (<i>d</i> = 33.36 ± 0.02pc, <i>T</i><sub>eff</sub> = 3373 ± 108 K) with an orbital period of 7.852 days.</p><br>
<p><i>Methods.</i> We use TESS data, ground-based multicolor photometry,<br>
 and radial velocity measurements with the InfraRed Doppler (IRD) <br>
instrument on the Subaru Telescope to validate the planetary nature of <br>
TOI-2136.01, and estimate the stellar and planetary parameters. We also <br>
conduct high-resolution transmission spectroscopy to search for helium <br>
in its atmosphere.</p><br>
<p><i>Results.</i> We confirm that TOI-2136.01 (now named TOI-2136b) is a bona fide planet with a planetary radius of <i>R</i><sub>p</sub> = 2.20 ± 0.07<i>R</i><sub>⊕</sub> and a mass of <i>M</i><sub>p</sub> = 4.7<sub>−2.6</sub><sup>+3.1</sup> <i>M</i><sub>⊕</sub>.<br>
 We also search for helium 10830 Å absorption lines and place an upper <br>
limit on the equivalent width of &lt;7.8 mÅ and on the absorption signal<br>
 of &lt;1.44% with 95% confidence.</p><br>
<p><i>Conclusions.</i> TOI-2136b is a sub-Neptune transiting a nearby and bright star (<i>J</i> = 10.8 mag), and is a potentially hycean planet, which is a new class of habitable planets with large oceans under a H<sub>2</sub>-rich<br>
 atmosphere, making it an excellent target for atmospheric studies to <br>
understand the formation, evolution, and habitability of the small <br>
planets.</p>}},
  author       = {{Kawauchi, K. and Murgas, F. and Palle, E. and Narita, N. and Fukui, A. and Hirano, T. and Parviainen, H. and Ishikawa, H. T. and Watanabe, N. and Esparaza-Borges, E. and Kuzuhara, M. and Orell-Miquel, J. and Krishnamurthy, V. and Mori, M. and Kagetani, T. and Zou, Y. and Isogai, K. and Livingston, J. H. and Howell, S. B. and Crouzet, N. and de Leon, J. P. and Kimura, T. and Kodama, T. and Korth, J. and Kurita, S. and Laza-Ramos, A. and Luque, R. and Madrigal-Aguado, A. and Miyakawa, K. and Morello, G. and Nishiumi, T. and Rodríguez, G. E. F. and Sánchez-Benavente, M. and Stangret, M. and Teng, H. and Terada, Y. and Gnilka, C. L. and Guerrero, N. and Harakawa, H. and Hodapp, K. and Hori, Y. and Ikoma, M. and Jacobson, S. and Konishi, M. and Kotani, T. and Kudo, T. and Kurokowa, T. and Kusakabe, N. and Nishikawa, J. and Omiya, M. and Serizawa, T. and Tamura, M and Ueda, A. and Vievard, S.}},
  issn         = {{0004-6361}},
  keywords     = {{Planets and satellites: atmospheres; Planets and satellites: detection; Planets and satellites: individual: TOI-2136b; techniques: photometric; Techniques: radial velocities}},
  language     = {{eng}},
  month        = {{10}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202243381}},
  doi          = {{10.1051/0004-6361/202243381}},
  volume       = {{666}},
  year         = {{2022}},
}