In:
The Astronomical Journal, American Astronomical Society, Vol. 160, No. 3 ( 2020-09-01), p. 114-
Kurzfassung:
We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright ( V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations—comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echellé Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Échelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements—and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P b = 5.19672 ± 0.00049 days, a mass of M b = 7.17 ± 0.66 M ⊕ , and a radius of R b = R ⊕ , whereas the outer warm Neptune, TOI-421 c, has a period of P c = 16.06819 ± 0.00035 days, a mass of M c = M ⊕ , a radius of R c = R ⊕ , and a density of ρ c = g cm −3 . With its characteristics, the outer planet ( ρ c = g cm −3 ) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Ly α transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH 4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed.
Materialart:
Online-Ressource
ISSN:
0004-6256
,
1538-3881
DOI:
10.3847/1538-3881/aba124
Sprache:
Unbekannt
Verlag:
American Astronomical Society
Publikationsdatum:
2020
ZDB Id:
127191-X
ZDB Id:
2003104-X
SSG:
16,12
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