Constraining planet structure from stellar chemistry: the cases of CoRoT-7, Kepler-10, and Kepler-93

Santos, N. C.; Adibekyan, V.; Mordasini, Christoph; Benz, W.; Delgado-Mena, E.; Dorn, Caroline; Buchhave, Lars A.; Figueira, P.; Mortier, A.; Pepe, F.; Santerne, A.; Sousa, S. G.; Udry, S.

doi:10.1051/0004-6361/201526850

Cited by 87 publications

(109 citation statements)

References 46 publications

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“…The abundances of planet-host stars as well as their origin in the Galaxy have been suggested to have an important influence on the frequency, composition, architecture, and formation history (Adibekyan et al 2012a;Dawson & Murray-Clay 2013;Adibekyan et al 2013;Santos et al 2015). We therefore decided to derive detailed abundances for several α-and iron-peak elements in HD 219828 using a combined HARPS spectrum, built from all the data available at the time of this publication 5 .…”

Section: Hd 219828: the Starmentioning

confidence: 99%

An extreme planetary system around HD 219828

Santos

Santerne

Faria

et al. 2016

A&A

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Context. With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. This wide diversity provides fundamental clues to the processes of planet formation and evolution. Aims. We present a full investigation of the HD 219828 system, a bright metal-rich star for which a hot Neptune has previously been detected. Methods. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD 219828. The spectra were used to characterise the star and its chemical abundances, as well as to check for spurious, activity induced signals. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. Results. We announce the discovery of a long period (P = 13.1 yr) massive (m sin i = 15.1 M Jup ) companion (HD 219828 c) in a very eccentric orbit (e = 0.81). The same data confirms the existence of a hot Neptune, HD 219828 b, with a minimum mass of 21 M ⊕ and a period of 3.83 days. The dynamical analysis shows that the system is stable, and that the equilibrium eccentricity of planet b is close to zero. Conclusions. The HD 219828 system is extreme and unique in several aspects. First, ammong all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like HD 219828, with a hot Neptune and a long-period massive companion are more frequent than similar systems with a hot Jupiter instead. This suggests that the formation of hot Neptunes follows a different path than the formation of their hot jovian counterparts. The high mass, long period, and eccentricity of HD 219828 c also make it a good target for Gaia astrometry as well as a potential target for atmospheric characterisation, using direct imaging or high-resolution spectroscopy. Astrometric observations will allow us to derive its real mass and orbital configuration. If a transit of HD 219828 b is detected, we will be able to fully characterise the system, including the relative orbital inclinations. With a clearly known mass, HD 219828 c may become a benchmark object for the range in between giant planets and brown dwarfs.

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Section: Hd 219828: the Starmentioning

confidence: 99%

An extreme planetary system around HD 219828

Santos

Santerne

Faria

et al. 2016

A&A

Self Cite

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“…Knowing the detailed chemistry of the host-star is also important, as this is thought to play a key role in conditions in the protoplanetary disk and subsequent planetary formation. For example, certain abundance ratios, such as Mg and Si relative to O, can affect coreto-mantle mass ratios in rocky exoplanets, while C/O ratios control ice chemistry in protoplanetary disks (e.g., Bond et al 2010;Delgado Mena et al 2010;Teske et al 2014;Santos et al 2015;Thiabaud et al 2015;Brewer & Fischer 2016;Dorn et al 2016;.…”

Section: Introductionmentioning

confidence: 99%

Chemical Abundances of M-Dwarfs from the Apogee Survey. I. The Exoplanet Hosting Stars Kepler-138 and Kepler-186

Souto

Cunha

García–Hernández

et al. 2017

ApJ

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We report the first detailed chemical abundance analysis of the exoplanet-hosting M-dwarf stars Kepler-138 and Kepler-186 from the analysis of high-resolution (R∼22,500) H-band spectra from the SDSS-IV-APOGEE survey. Chemical abundances of 13 elements-C, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe-are extracted from the APOGEE spectra of these early M-dwarfs via spectrum syntheses computed with an improved line list that takes into account H 2 O and FeH lines. This paper demonstrates that APOGEE spectra can be analyzed to determine

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“…In this paper we take a complementary approach to Santos et al (2015) and consider the effect of the chemical composition on the formation and migration of planets. We focus on the role of oxygen and silicon, as well as the overall metallicity of the star.…”

Section: Introductionmentioning

confidence: 99%

Influence of the water content in protoplanetary discs on planet migration and formation

Bitsch

Johansen

2016

A&A

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The temperature and density profiles of protoplanetary discs depend crucially on the mass fraction of micrometre-sized dust grains and on their chemical composition. A larger abundance of micrometre-sized grains leads to an overall heating of the disc, so that the water ice line moves further away from the star. An increase in the water fraction inside the disc, maintaining a fixed dust abundance, increases the temperature in the icy regions of the disc and lowers the temperature in the inner regions. Discs with a larger silicate fraction have the opposite effect. Here we explore the consequence of the dust composition and abundance for the formation and migration of planets. We find that discs with low water content can only sustain outwards migration for planets up to 4 Earth masses, while outwards migration in discs with a larger water content persists up to 8 Earth masses in the late stages of the disc evolution. Icy planetary cores that do not reach run-away gas accretion can thus migrate to orbits close to the host star if the water abundance is low. Our results imply that hot and warm super-Earths found in exoplanet surveys could have formed beyond the ice line and thus contain a significant fraction in water. These water-rich super-Earths should orbit primarily around stars with a low oxygen abundance, where a low oxygen abundance is caused by either a low water-to-silicate ratio or by overall low metallicity.

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Constraining planet structure from stellar chemistry: the cases of CoRoT-7, Kepler-10, and Kepler-93

Cited by 87 publications

References 46 publications

An extreme planetary system around HD 219828

An extreme planetary system around HD 219828

Chemical Abundances of M-Dwarfs from the Apogee Survey. I. The Exoplanet Hosting Stars Kepler-138 and Kepler-186

Influence of the water content in protoplanetary discs on planet migration and formation

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