An unusually low density ultra-short period super-Earth and three mini-Neptunes around the old star TOI-561

Lacedelli, G.; Malavolta, L.; Borsato, L.; Piotto, G.; Nardiello, D.; Mortier, A.; Stalport, M.; Cameron, A. Collier; Poretti, E.; Buchhave, Lars A.; López‐Morales, Mercedes; Nascimbeni, V.; Wilson, T. G.; Udry, S.; Latham, David W.; Bonomo, A. S.; Damasso, M.; Dumusque, X.; Jenkins, Jon M.; Lovis, C.; Rice, Ken; Sasselov, Dimitar; Winn, Joshua N.; Andreuzzi, G.; Cosentino, R.; Charbonneau, David; Fabrizio, L. Di; Fiorenzano, A. F. Martínez; Ghedina, A.; Harutyunyan, A.; Lienhard, Florian; Micela, G.; Molinari, E.; Pagano, I.; Pepe, F.; Phillips, David F.; Pinamonti, M.; Ricker, G.; Scandariato, G.; Sozzetti, A.; Watson, Christopher A.

doi:10.1093/mnras/staa3728

Cited by 39 publications

(33 citation statements)

References 123 publications

(122 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Out of 4330 confirmed planets (as of 2020 May 11) 364 were listed with masses below 10 M ⊕ orbiting F,G,K, type stars with effective temperatures (T eff ) between 4500 and 6500 K. We selected the 56 planets that had a precision in both mass and radius better than 30%. To this sample we added two planetary systems that were published after our search date: K2-38 (consisting of two low-mass planets) (32) and TOI-561 (consisting of one super-Earth and three mini-Neptunes) (26).…”

Section: The Samplementioning

confidence: 99%

See 1 more Smart Citation

A compositional link between rocky exoplanets and their host stars

Adibekyan

Dorn

Sousa

et al. 2021

Science

113

125

View full text Add to dashboard Cite

The interior compositions of small rocky exoplanets cannot be observed directly but are expected to relate to the composition of the host star. Adibekyan et al. analyzed a sample of rocky exoplanets, inferring the planets' iron fractions by combining their masses and radii with an interior structure model. The iron fractions of the host stars were calculated from stellar elemental abundances. The two iron fractions, that of the planets and that of the stars, correlate with each other, but the slope is steeper than 1, indicating that planet formation processes modify the compositions of rocky planets.-KTS Stars and planets both form by accreting material from a surrounding disk. Because they grow from the same material, theory predicts that there should be a relationship between their compositions. In this study, we search for a compositional link between rocky exoplanets and their host stars. We estimate the iron-mass fraction of rocky exoplanets from their masses and radii and compare it with the compositions of their host stars, which we assume reflect the compositions of the protoplanetary disks. We find a correlation (but not a 1:1 relationship) between these two quantities, with a slope of >4, which we interpret as being attributable to planet formation processes. Super-Earths and super-Mercuries appear to be distinct populations with differing compositions, implying differences in their formation processes.

show abstract

Section: The Samplementioning

confidence: 99%

“…All but one of the stars in our sample are members of the Milky Way's thin disk. The exception is the ultra-short period planet TOI-561 b, which orbits a metal-poor star in the thick disk; it was previously found to have an unusually low density (26). Figs.…”

mentioning

confidence: 99%

A compositional link between rocky exoplanets and their host stars

Adibekyan

Dorn

Sousa

et al. 2021

Science

113

125

View full text Add to dashboard Cite

show abstract

“…Within this context, TOI-561, announced simultaneously by Lacedelli et al (2021) and Weiss et al (2021) (L21 and W21 hereafter, respectively), is a particularly interesting system, both from the stellar (Section 2.1) and planetary (Section 2.2) perspective. The low stellar metallicity, the presence of an ultra-short period (USP) planet, where USP planets are meant here as planets with periods shorter than one day and radii smaller than 2 R ⊕ , and the complexity of its planetary configuration make TOI-561 an appealing target for in-depth investigations.…”

mentioning

confidence: 99%

Investigating the architecture and internal structure of the TOI-561 system planets with CHEOPS, HARPS-N, and TESS

Lacedelli

Wilson

Malavolta

et al. 2022

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We present a precise characterization of the TOI-561 planetary system obtained by combining previously published data with TESS and CHEOPS photometry, and a new set of 62 HARPS-N radial velocities (RVs). Our joint analysis confirms the presence of four transiting planets, namely TOI-561 b (P = 0.45 d, R = 1.42 R⊕, M = 2.0 M⊕), c (P = 10.78 d, R = 2.91 R⊕, M = 5.4 M⊕), d (P = 25.7 d, R = 2.82 R⊕, M = 13.2 M⊕) and e (P = 77 d, R = 2.55 R⊕, M = 12.6 R⊕). Moreover, we identify an additional, long-period signal (>450 d) in the RVs, which could be due to either an external planetary companion or to stellar magnetic activity. The precise masses and radii obtained for the four planets allowed us to conduct interior structure and atmospheric escape modelling. TOI-561 b is confirmed to be the lowest density (ρb = 3.8 ± 0.5 g cm−3) ultra-short period (USP) planet known to date, and the low metallicity of the host star makes it consistent with the general bulk density-stellar metallicity trend. According to our interior structure modelling, planet b has basically no gas envelope, and it could host a certain amount of water. In contrast, TOI-561 c, d, and e likely retained an H/He envelope, in addition to a possibly large water layer. The inferred planetary compositions suggest different atmospheric evolutionary paths, with planets b and c having experienced significant gas loss, and planets d and e showing an atmospheric content consistent with the original one. The uniqueness of the USP planet, the presence of the long-period planet TOI-561 e, and the complex architecture make this system an appealing target for follow-up studies.

show abstract

“…TOI-500 is not the only existing system for which the low eccentricity channel may work. For instance, TOI-561 [35,36] and CoRoT-7 [16,37] could also have migrated with the same scenario. CoRoT-7 is a two-planet system with no analogs thus far: an active star with a USP planet and a 3 d-period Neptune.…”

Section: Main Textmentioning

confidence: 99%

A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system

Serrano,

Gandolfi,

Mustill

et al. 2022

Preprint

View full text Add to dashboard Cite

It is commonly accepted that exoplanets with orbital periods shorter than 1 day, also known as ultra-short period (USP) planets, formed further out within their natal protoplanetary disk, before migrating to their current-day orbits via dynamical interactions. One of the most accepted theories suggests a violent scenario involving high-eccentricity migration followed by tidal circularization. Here, we present the discovery of a four planet system orbiting the bright (V=10.5) K6 dwarf star TOI-500. The innermost planet is a transiting, Earth-sized USP planet with an orbital period of ∼13 hours, a mass of 1.42 ± 0.18 M ⊕ , a radius of 1.166 +0.061 −0.058 R ⊕ , and a mean density of 4.89 +1.03 −0.88 g cm −3 . Via Doppler spectroscopy, we discovered that the system hosts three outer planets on nearly circular orbits with periods of 6.6, 26.2, and 61.3 d and minimum masses of 5.03 ± 0.41 M ⊕ , 33.12 ± 0.88 M ⊕ , and 15.05 +1.12 −1.11 M ⊕ , respectively. The presence of both a USP planet and a low-mass object on a 6.6-day orbit indicates that the architecture of this system can be explained via a scenario in which the planets started on low-eccentricity orbits, then moved inwards through a quasi-static secular migration. Our numerical simulations show that this migration channel can bring TOI-500 b to its current location in 2 Gyrs, starting from an initial orbit of 0.02 au. TOI-500 is the first four planet system known to host a USP Earth analog whose current architecture can be explained via a non-violent migration scenario.

show abstract

An unusually low density ultra-short period super-Earth and three mini-Neptunes around the old star TOI-561

Cited by 39 publications

References 123 publications

A compositional link between rocky exoplanets and their host stars

A compositional link between rocky exoplanets and their host stars

Investigating the architecture and internal structure of the TOI-561 system planets with CHEOPS, HARPS-N, and TESS

A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system

Contact Info

Product

Resources

About