An unusually low-density super-Earth transiting the bright early-type M-dwarf GJ 1018 (TOI-244)

Author:

Castro-González A.ORCID,Demangeon O. D. S.ORCID,Lillo-Box J.ORCID,Lovis C.ORCID,Lavie B.ORCID,Adibekyan V.ORCID,Acuña L.ORCID,Deleuil M.ORCID,Aguichine A.ORCID,Zapatero Osorio M. R.ORCID,Tabernero H. M.ORCID,Davoult J.ORCID,Alibert Y.ORCID,Santos N.ORCID,Sousa S. G.ORCID,Antoniadis-Karnavas A.,Borsa F.ORCID,Winn J. N.ORCID,Allende Prieto C.,Figueira P.ORCID,Jenkins J. M.,Sozzetti A.ORCID,Damasso M.ORCID,Silva A. M.ORCID,Astudillo-Defru N.ORCID,Barros S. C. C.,Bonfils X.,Cristiani S.ORCID,Di Marcantonio P.ORCID,González Hernández J. I.ORCID,Curto G. Lo,Martins C. J. A. P.ORCID,Nunes N. J.ORCID,Palle E.ORCID,Pepe F.ORCID,Seager S.,Suárez Mascareño A.ORCID

Abstract

Context. Small planets located at the lower mode of the bimodal radius distribution are generally assumed to be composed of iron and silicates in a proportion similar to that of the Earth. However, recent discoveries are revealing a new group of low-density planets that are inconsistent with that description. Aims. We intend to confirm and characterize the TESS planet candidate TOI-244.01, which orbits the bright (K = 7.97 mag), nearby (d = 22 pc), and early-type (M2.5 V) M-dwarf star GJ 1018 with an orbital period of 7.4 days. Methods. We used Markov chain Monte Carlo methods to model 57 precise radial velocity measurements acquired by the ESPRESSO spectrograph together with TESS photometry and complementary HARPS data. Our model includes a planetary component and Gaussian processes aimed at modeling the correlated stellar and instrumental noise. Results. We find TOI-244 b to be a super-Earth with a radius of Rp = 1.52 ± 0.12 R and a mass of Mp = 2.68 ± 0.30 M. These values correspond to a density of ρ = 4.2 ± 1.1 g cm−3, which is below what would be expected for an Earth-like composition. We find that atmospheric loss processes may have been efficient to remove a potential primordial hydrogen envelope, but high mean molecular weight volatiles such as water could have been retained. Our internal structure modeling suggests that TOI-244 b has a 479−96+128 km thick hydrosphere over a 1.17 ± 0.09 R solid structure composed of a Fe-rich core and a silicate-dominated mantle compatible with that of the Earth. On a population level, we find two tentative trends in the density-metallicity and density-insolation parameter space for the low-density super-Earths, which may hint at their composition. Conclusions. With a 8% precision in radius and 12% precision in mass, TOI-244 b is among the most precisely characterized super-Earths, which, together with the likely presence of an extended hydrosphere, makes it a key target for atmospheric observations.

Funder

NASA

Publisher

EDP Sciences

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 2 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3