A compact system of small planets around a former red-giant star

Charpinet, S.; Fontaine, G.; Brassard, P.; Green, Elizabeth M.; Grootel, Valérie Van; Randall, S. K.; Silvotti, R.; Baran, A.; Østensen, R. H.; Kawaler, S. D.; Telting, J. H.

doi:10.1038/nature10631

Cited by 174 publications

(206 citation statements)

References 28 publications

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“…Examples are the 1.25 MJ planet (where MJ is the mass of Jupiter) orbiting 0.116 au from a horizontal branch star (Setiawan et al 2010), two Earth-sized objects orbiting a subdwarf B star at a separation of 0.0060 and 0.0076 au (Charpinet et al 2011), or three earth-sized planets orbiting a subdwarf B pulsator (Silvotti et al 2014). These planets must have been engulfed in the envelope of the giant star that became the subdwarf star today.…”

Section: Introductionmentioning

confidence: 99%

“…These planets must have been engulfed in the envelope of the giant star that became the subdwarf star today. Charpinet et al (2011) and Passy et al (2012b) showed how planets may have been much more massive initially and lost much of their mass in the CE phase. However, they could not determine how the core of the planets survived the interaction instead of plunging into the core of the giant.…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic simulations of the interaction between giant stars and planets

Staff

Marco

Wood

et al. 2016

Mon. Not. R. Astron. Soc.

127

100

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We present the results of hydrodynamic simulations of the interaction between a 10 Jupiter mass planet and a red or asymptotic giant branch stars, both with a zeroage main sequence mass of 3.5 M ⊙ . Dynamic in-spiral timescales are of the order of few years and a few decades for the red and asymptotic giant branch stars, respectively. The planets will eventually be destroyed at a separation from the core of the giants smaller than the resolution of our simulations, either through evaporation or tidal disruption. As the planets in-spiral, the giant stars' envelopes are somewhat puffed up. Based on relatively long timescales and even considering the fact that further inspiral should take place before the planets are destroyed, we predict that the merger would be difficult to observe, with only a relatively small, slow brightening. Very little mass is unbound in the process. These conclusions may change if the planet's orbit enhances the star's main pulsation modes. Based on the angular momentum transfer, we also suspect that this star-planet interaction may be unable to lead to large scale outflows via the rotation-mediated dynamo effect of Nordhaus and Blackman. Detectable pollution from the destroyed planets would only result for the lightest, lowest metallicity stars. We furthermore find that in both simulations the planets move through the outer stellar envelopes at Mach-3 to Mach-5, reaching Mach-1 towards the end of the simulations. The gravitational drag force decreases and the in-spiral slows down at the sonic transition, as predicted analytically.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrodynamic simulations of the interaction between giant stars and planets

Staff

Marco

Wood

et al. 2016

Mon. Not. R. Astron. Soc.

127

100

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“…Villaver & Livio 2009;Nordhaus & Spiegel 2013). For example, Charpinet et al (2011) have used Kepler to deduce the presence of two Earth-sized planets orbiting a hot B subdwarf star (a red giant stripped of its envelope, and destined to become a WD), with 5.7 hr and 8.2 hr periods. Reflection or thermal re-emission of the WD radiation by the planets modulates the WD light by ∼ 50 ppm.…”

Section: Close Companions To Wdsmentioning

confidence: 99%

Kepler and the seven dwarfs: detection of low-level day-time-scale periodic photometric variations in white dwarfs

Maoz

Mazeh

McQuillan

2014

Monthly Notices of the Royal Astronomical Society

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We make use of the high photometric precision of Kepler to search for periodic modulations among 14 normal (DA-and DB-type, likely non-magnetic) hot white dwarfs (WDs). In five, and possibly up to seven of the WDs, we detect periodic, ∼ 2 hr to 10 d, variations, with semi-amplitudes of 60-2000 ppm, lower than ever seen in WDs. We consider various explanations: WD rotation combined with magnetic cool spots; rotation combined with magnetic dichroism; rotation combined with hot spots from an interstellar-medium accretion flow; transits by size ∼ 50-200 km objects; relativistic beaming due to reflex motion caused by a cool companion WD; or reflection/reradiation of the primary WD light by a brown-dwarf or giant-planet companion, undergoing illumination phases as it orbits the WD. Each mechanism could be behind some of the variable WDs, but could not be responsible for all five to seven variable cases. Alternatively, the periodicity may arise from UV metal-line opacity, associated with accretion of rocky material, a phenomenon seen in ∼ 50% of hot WDs. Nonuniform UV opacity, combined with WD rotation and fluorescent optical re-emission of the absorbed UV energy, could perhaps explain our findings. Even if reflection by a planet is the cause in only a few of the seven cases, it would imply that hot Jupiters are very common around WDs. If some of the rotation-related mechanisms are at work, then normal WDs rotate as slowly as do peculiar WDs, the only kind for which precise rotation measurements have been possible to date.

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“…However, little is known about the evolution of planetary systems beyond the main sequence lifetime of their host stars. Planets have been discovered around (sub)giant stars (Johnson et al 2011;Gettel et al 2012) and horizontal branch stars (Silvotti et al 2007;Setiawan et al 2010;Charpinet et al 2011). There is only one planetarymass object detected with direct imaging around a white dwarf (WD 0806-661;Luhman et al 2011), although theoretical calculations show that many more planets can survive the red giant stage (Burleigh et al 2002;Jura 2008;Mustill & Villaver 2012;Nordhaus & Spiegel 2013).…”

Section: Introductionmentioning

confidence: 99%

An extreme-AO search for giant planets around a white dwarf

Ertel

Wahhaj

et al. 2015

A&A

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Context. Little is known about the planetary systems around single white dwarfs, although there is strong evidence that they do exist. Aims. We performed a pilot study with the extreme-AO system on the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) on the Very Large Telescopes (VLT) to look for giant planets around a young white dwarf, GD 50. Methods. We were awarded science verification time on the new ESO instrument SPHERE. Observations were made with the InfraRed Dual-band Imager and Spectrograph in classical imaging mode in H band. Results. Despite the faintness of the target (14.2 mag in R band), the AO loop was closed and a strehl of 37% was reached in H band. No objects were detected around GD 50. We achieved a 5-sigma contrast of 6.2, 8.0, and 8.25 mag at 0. 2, 0. 4, and 0. 6 and beyond, respectively. We exclude any substellar objects more massive than 4.0 M J at 6.2 au, 2.9 M J at 12.4 au, and 2.8 M J at 18.6 au and beyond. This rivals the previous upper limit set by Spitzer. We further show that SPHERE is the most promising instrument available to search for close-in substellar objects around nearby white dwarfs.

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A compact system of small planets around a former red-giant star

Cited by 174 publications

References 28 publications

Hydrodynamic simulations of the interaction between giant stars and planets

Hydrodynamic simulations of the interaction between giant stars and planets

Kepler and the seven dwarfs: detection of low-level day-time-scale periodic photometric variations in white dwarfs

An extreme-AO search for giant planets around a white dwarf

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