Extrasolar planets and brown dwarfs around AF-type stars

Borgniet, S.; Lagrange, A. M.; Meunier, N.; Galland, F.; Arnold, L.; Astudillo-Defru, N.; Beuzit, Jean-Luc; Boisse, I.; Bonfils, X.; Bouchy, F.; Debondt, K.; Deleuil, M.; Delfosse, X.; Desort, M.; Díaz, R. F.; Eggenberger, A.; Ehrenreich, D.; Forveille, T.; Hébrard, G.; Loeillet, B.; Lovis, C.; Montagnier, G.; Moutou, C.; Pepe, F.; Perrier, C.; Pont, F.; Queloz, D.; Santerne, A.; Santos, N. C.; Ségransan, D.; Silva, R. da; Sivan, J. P.; Udry, S.; Vidal‐Madjar, A.

doi:10.1051/0004-6361/201833431

Cited by 39 publications

(41 citation statements)

References 85 publications

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“…Although RV-surveys of A-type stars are very challenging, Borgniet et al (2019) calculated the occurrence rate of closein BD and giant planets from their sample with HARPS and SOPHIE. They concluded that the giant planet occurrence rate is lower than 4.5 per cent.…”

Section: Discussionmentioning

confidence: 99%

Lack of close-in, massive planets of main-sequence A-type stars from Kepler

Sabotta

Kabáth

Korth

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Some theories of planet formation and evolution predict that intermediate-mass stars host more hot Jupiters than Sun-like stars, others reach the conclusion that such objects are very rare. By determining the frequencies of those planets we can test those theories.Based on the analysis of Kepler light curves it has been suggested that about 8 per cent of the intermediate-mass stars could have a close-in substellar companion. This would indicate a very high frequency of such objects. Up to now, there was no satisfactory proof or test of this hypothesis.We studied a previously reported sample of 166 planet candidates around mainsequence A-type stars in the Kepler field. We selected six of them for which we obtained extensive long-term radial velocity measurements with the Alfred-Jensch 2-m telescope in Tautenburg and the Perek 2-m telescope in Ondřejov. We derive upper limits of the masses of the planet candidates. We show that we are able to detect this kind of planet with our telescopes and their instrumentation using the example of MASCARA-1 b.With the transit finding pipeline EXOTRANS we confirm that there is no single transit event from a Jupiter-like planet in the light curves of those 166 stars. We furthermore determine that the upper limit for the occurrence rate of close-in, massive planets for A-type stars in the Kepler sample is around 0.75 per cent.We argue that there is currently little evidence for a very high frequency of close-in, massive planets of intermediate-mass stars.

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Section: Discussionmentioning

confidence: 99%

Lack of close-in, massive planets of main-sequence A-type stars from Kepler

Sabotta

Kabáth

Korth

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…In terms of stellar rotation, Borgniet et al (2014) reported sin ★ = 6.3 ± 1 km s −1 . For the rotation period, Borgniet et al (2019a) found strong peaks of ∼ 2 and ∼ 4 d in the Lomb Scargle periodogram of the RV residuals. In addition, they found ∼ 2 and ∼ 3 d periodicities in the bisector velocity span, which was used as a diagnosis of the stellar variability.…”

Section: The Starmentioning

confidence: 90%

“…In addition, they found ∼ 2 and ∼ 3 d periodicities in the bisector velocity span, which was used as a diagnosis of the stellar variability. These signals all have false alarm probabilities of < 1 per cent, and are attributed to stellar rotation by Borgniet et al (2019a). To estimate the stellar spin inclination, we assume the ∼ 2 − 4 d periods are indeed close to the stellar rotation period, and adopt ★ = 3 ± 1 d. Combining ★ , sin ★ , and ★ , we get ★ = 24 +30 −10…”

Section: The Starmentioning

confidence: 99%

“…In this paper, we study planet-disc alignment in HD 113337 and HD 38529, which both host multiple giant planets (Fischer et al 2003;Borgniet et al 2019a), debris discs (Moro-Martín et al 2007b;Rhee et al 2007), and wide M-type stellar companions (Montes et al 2018). In both systems, the outer planets detected by radial velocity (RV) have masses ( ) and semimajor axes ( ) comparable to directly imaged planets like Pic b ( ∼ 13 Jup and ∼ 11 au, Gravity Collaboration et al 2020): HD 113337 c has sin ∼ 7 Jup and ∼ 4.8 au (Borgniet et al 2019a), while HD 38529 c has sin ∼ 13 Jup and ∼ 3.6 au (Fischer et al 2003). In these two systems, comparison of Gaia DR2 and Hipparcos astrometry shows that the stars exhibit significant differences in proper motion indicative of orbital motion (e.g Brandt 2018; Kervella et al 2019), which we find enables full orbit characterizations of the outer planets.…”

Section: Introductionmentioning

confidence: 99%

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Mutual inclinations between giant planets and their debris discs in HD 113337 and HD 38529

Xuan

Kennedy

Wyatt

et al. 2020

Monthly Notices of the Royal Astronomical Society

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HD 113337 and HD 38529 host pairs of giant planets, a debris disc, and wide M-type stellar companions. We measure the disc orientation with resolved images from Herschel and constrain the three-dimensional orbits of the outer planets with Gaia DR2 and Hipparcos astrometry. Resolved disc modelling leaves degeneracy in the disc orientation, so we derive four separate planet-disc mutual inclination (ΔI) solutions. The most aligned solutions give ΔI = 17 − 32○ for HD 113337 and ΔI = 21 − 45○ for HD 38529 (both 1σ). In both systems, there is a small probability (<0.3 per cent) that the planet and disc are nearly aligned (ΔI < 3○). The stellar and planetary companions cause the orbits of disc material to precess about a plane defined by the forced inclination. We determine this as well as the precession time-scale to interpret the mutual inclination results. We find that the debris discs in both systems could be warped via joint influences of the outer planet and stellar companion, potentially explaining the observed misalignments. However, this requires HD 113337 to be old (0.8-1.7 Gyr), whereas if young (14-21 Myr), the observed misalignment in HD 113337 could be inherited from the protoplanetary disc phase. For both systems, the inclination of the stellar spin axis is consistent with the disc and outer planet inclinations, which instead supports system-wide alignment or near alignment. High-resolution observations of the discs and improved constraints on the planetary orbits would provide firmer conclusions about the (mis)alignment status.

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“…Marois et al 2008;Chauvin et al 2017). Recent radial velocity studies indicate an increase in both the occurence rate and orbital separations of Jupiter-mass planets with increasing stellar mass (Borgniet et al 2019). Surveys targeting sub-giant stars with M ≥ 1.6 M , the so-called "retired A stars", confirm this trend: the giant planet occurrence increases with stellar mass up to 2M (Ghezzi et al 2018).…”

Section: Planet Occurrences At Large Separations Around Aandf Starsmentioning

confidence: 90%

Cold Giant Planets Evaporated by Hot White Dwarfs

Schreiber

Gänsicke

Toloza

et al. 2019

ApJL

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Atmospheric escape from close-in Neptunes and hot Jupiters around sun-like stars driven by extreme ultraviolet (EUV) irradiation plays an important role in the evolution of exo-planets and in shaping their ensemble properties. Intermediate and low mass stars are brightest at EUV wavelengths at the very end of their lives, after they have expelled their envelopes and evolved into hot white dwarfs. Yet the effect of the intense EUV irradiation of giant planets orbiting young white dwarfs has not been assessed. We show that the giant planets in the solar system will experience significant hydrodynamic escape caused by the EUV irradiation from the white dwarf left behind by the Sun. A fraction of the evaporated volatiles will be accreted by the solar white dwarf, resulting in detectable photospheric absorption lines. As a large number of the currently known extra-solar giant planets will survive the metamorphosis of their host stars into white dwarfs, observational signatures of accretion from evaporating planetary atmospheres are expected to be common. In fact, one third of the known hot single white dwarfs show photospheric absorption lines of volatile elements, which we argue are indicative of ongoing accretion from evaporating planets. The fraction of volatile contaminated hot white dwarfs strongly decreases as they cool. We show that accretion from evaporating planetary atmospheres naturally explains this temperature dependence if more than 50 per cent of hot white dwarfs still host giant planets.

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Extrasolar planets and brown dwarfs around AF-type stars

Cited by 39 publications

References 85 publications

Lack of close-in, massive planets of main-sequence A-type stars from Kepler

Lack of close-in, massive planets of main-sequence A-type stars from Kepler

Mutual inclinations between giant planets and their debris discs in HD 113337 and HD 38529

Cold Giant Planets Evaporated by Hot White Dwarfs

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