The Obliquity of HIP 67522 b: A 17 Myr Old Transiting Hot, Jupiter-sized Planet

Abstract HIP 67522 b is a 17 Myr old, close-in (P orb = 6.96 days), Jupiter-sized (R = 10 R ⊕) transiting planet orbiting a Sun-like star in the Sco–Cen OB association. We present our measurement of the system’s projected orbital obliquity via two spectroscopic transit observations using the CHIRON spectroscopic facility. We present a global model that accounts for large surface brightness features typical of such young stars during spectroscopic transit observations. With a value of ∣ λ ∣ = 5.8 − 5.7 + 2.8 ° it is unlikely that this well-aligned system is the result of a high-eccentricity-driven migration history. By being the youngest planet with a known obliquity, HIP 67522 b holds a special place in contributing to our understanding of giant planet formation and evolution. Our analysis shows the feasibility of such measurements for young and very active stars.

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Full exploration of the giant planet population around β Pictoris

Astronomy and Astrophysics ◽

10.1051/0004-6361/201730436 ◽

2018 ◽

Vol 612 ◽

pp. A108 ◽

Cited By ~ 11

Author(s):

A.-M. Lagrange ◽

M. Keppler ◽

N. Meunier ◽

J. Lannier ◽

H. Beust ◽

...

Keyword(s):

Extrasolar Planets ◽

Giant Planet ◽

Young Stars ◽

Giant Planets ◽

Close Orbit ◽

Wide Range ◽

Detection Probabilities ◽

Solar Type ◽

Formation And Evolution ◽

The One

Context. The search for extrasolar planets has been limited so far to close orbit (typ. ≤5 au) planets around mature solar-type stars on the one hand, and to planets on wide orbits (≥10 au) around young stars on the other hand. To get a better view of the full giant planet population, we have started a survey to search for giant planets around a sample of carefully selected young stars. Aims. This paper aims at exploring the giant planet population around one of our targets, β Pictoris, over a wide range of separations. With a disk and a planet already known, the β Pictoris system is indeed a very precious system for studies of planetary formation and evolution, as well as of planet–disk interactions. Methods. We analyse more than 2000 HARPS high-resolution spectra taken over 13 years as well as NaCo images recorded between 2003 and 2016. We combine these data to compute the detection probabilities of planets throughout the disk, from a fraction of au to a few dozen au. Results. We exclude the presence of planets more massive than 3 MJup closer than 1 au and further than 10 au, with a 90% probability. 15+ MJup companions are excluded throughout the disk except between 3 and 5 au with a 90% probability. In this region, we exclude companions with masses larger than 18 (resp. 30) MJup with probabilities of 60 (resp. 90) %.

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Methods for computing giant planet formation and evolution

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2004.08570.x ◽

2005 ◽

Vol 356 (4) ◽

pp. 1383-1395 ◽

Cited By ~ 10

Author(s):

O. G. Benvenuto ◽

A. Brunini

Keyword(s):

Planet Formation ◽

Giant Planet ◽

Formation And Evolution

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Modes of Gaseous Planet Formation

Symposium - International Astronomical Union ◽

10.1017/s0074180900217725 ◽

2004 ◽

Vol 202 ◽

pp. 141-148 ◽

Cited By ~ 1

Author(s):

Alan P. Boss

Keyword(s):

Planet Formation ◽

Gravitational Instability ◽

Giant Planet ◽

Solid Core ◽

New Era ◽

Advantages And Disadvantages ◽

Nearby Stars ◽

Formation And Evolution ◽

Gas Giant ◽

Core Accretion

The discovery of gas giant planets around nearby stars has launched a new era in our understanding of the formation and evolution of planetary systems. However, none of the over four dozen companions detected to date strongly resembles Jupiter or Saturn: their inferred masses range from sub-Saturn-mass to 10 Jupiter-masses or more, while their orbits extend from periods of a few days to a few years. Given this situation, it seems prudent to re-examine mechanisms for gas giant planet formation. The two extreme cases are top-down or bottom-up. The latter is the core accretion mechanism, long favored for our Solar System, where a roughly 10 Earth-mass solid core forms by collisional accumulation of planetesimals, followed by hydrodynamic accretion of a gaseous envelope. The former is the long-discarded disk instability mechanism, where the protoplanetary disk forms self-gravitating, gaseous protoplanets through a gravitational instability of the gas, accompanied by settling and coagulation of dust grains to form solid cores. Both of these mechanisms have a number of advantages and disadvantages, making a purely theoretical choice between them difficult at present. Observations should be able to decide the dominant mechanism by dating the epoch of gas giant planet formation: core accretion requires more than a million years to form a Jupiter-mass planet, whereas disk instability is much more rapid.

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Orbital misalignment of the super-Earth π Men c with the spin of its star

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab237 ◽

2021 ◽

Vol 502 (2) ◽

pp. 2893-2911 ◽

Cited By ~ 1

Author(s):

Vedad Kunovac Hodžić ◽

Amaury H M J Triaud ◽

Heather M Cegla ◽

William J Chaplin ◽

Guy R Davies

Keyword(s):

Time Series ◽

High Resolution ◽

Radial Velocity ◽

Gaussian Processes ◽

Giant Planet ◽

Spin Axis ◽

Physical Parameters ◽

Eccentric Orbit ◽

High Eccentricity ◽

Migration History

ABSTRACT Planet–planet scattering events can leave an observable trace of a planet’s migration history in the form of orbital misalignment with respect to the stellar spin axis, which is measurable from spectroscopic time-series taken during transit. We present high-resolution spectroscopic transits observed with ESPRESSO of the close-in super-Earth π Men c. The system also contains an outer giant planet on a wide, eccentric orbit, recently found to be inclined with respect to the inner planetary orbit. These characteristics are reminiscent of past dynamical interactions. We successfully retrieve the planet-occulted light during transit, and find evidence that the orbit of π Men c is moderately misaligned with the stellar spin axis with λ = − 24${_{.}^{\circ}}$0 ± 4${_{.}^{\circ}}$1 ($\psi = {26{_{.}^{\circ}} 9}^{+5{_{.}^{\circ}}8 }_{-4{_{.}^{\circ}}7 }$). This is consistent with the super-Earth π Men c having followed a high-eccentricity migration followed by tidal circularization, and hints that super-Earths can form at large distances from their star. We also detect clear signatures of solar-like oscillations within our ESPRESSO radial velocity time series, where we reach a radial velocity precision of ∼20 cm s−1. We model the oscillations using Gaussian processes (GPs) and retrieve a frequency of maximum oscillation, $\nu _\mathrm{max}{} = 2771^{+65}_{-60}\, \mu \mathrm{Hz}$. These oscillations make it challenging to detect the Rossiter–McLaughlin effect using traditional methods. We are, however, successful using the reloaded Rossiter–McLaughlin approach. Finally, in the appendix, we also present physical parameters and ephemerides for π Men c from a GP transit analysis of the full Transiting Exoplanet Survey Satellite Cycle 1 data.

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Discovery of a stellar companion to HD 131399A

Astronomy and Astrophysics ◽

10.1051/0004-6361/201730978 ◽

2017 ◽

Vol 608 ◽

pp. L9 ◽

Cited By ~ 1

Author(s):

A.-M. Lagrange ◽

M. Keppler ◽

H. Beust ◽

L. Rodet ◽

N. Meunier ◽

...

Keyword(s):

High Resolution ◽

Binary System ◽

Planet Formation ◽

Giant Planet ◽

Dynamical Evolution ◽

Young Stars ◽

Circumstellar Disk ◽

Mass Star ◽

Low Mass

Context. The giant exoplanets imaged on wide orbits (≥10 au) around young stars challenge the classical theories of planet formation. The presence of perturbing bodies could have played a role in the dynamical evolution of the planets once formed. Aims. We aim to search for close companions to HD 131399, a star around which a giant planet has been discovered, at a projected separation of about 80 au. The star also appears to be a member of a wide (320 au) binary system. Methods. We recorded HARPS high resolution spectra in January 2017. Results. We find that HD 131399A is probably seen close to pole-on. We discover a low mass star companion that orbits with a period of about 10 days on a misaligned orbit. Even though the companion does not have an impact on the current dynamical evolution of the planet, it could have played a role in its setting and in clearing the circumstellar disk from which the planet may originate.

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Direct imaging of exoplanets

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2013.0090 ◽

2014 ◽

Vol 372 (2014) ◽

pp. 20130090 ◽

Cited By ~ 3

Author(s):

Anne-Marie Lagrange

Keyword(s):

Radial Velocity ◽

Second Generation ◽

Giant Planet ◽

Temporal Variations ◽

Young Stars ◽

Giant Planets ◽

Direct Imaging ◽

Formation And Evolution ◽

Near Future ◽

Central Stars

Most of the exoplanets known today have been discovered by indirect techniques, based on the study of the host star radial velocity or photometric temporal variations. These detections allowed the study of the planet populations in the first 5–8 AU from the central stars and have provided precious information on the way planets form and evolve at such separations. Direct imaging on 8–10 m class telescopes allows the detection of giant planets at larger separations (currently typically more than 5–10 AU) complementing the indirect techniques. So far, only a few planets have been imaged around young stars, but each of them provides an opportunity for unique dedicated studies of their orbital, physical and atmospheric properties and sometimes also on the interaction with the ‘second-generation’, debris discs. These few detections already challenge formation theories. In this paper, I present the results of direct imaging surveys obtained so far, and what they already tell us about giant planet (GP) formation and evolution. Individual and emblematic cases are detailed; they illustrate what future instruments will routinely deliver for a much larger number of stars. I also point out the limitations of this approach, as well as the needs for further work in terms of planet formation modelling. I finally present the progress expected in direct imaging in the near future, thanks in particular to forthcoming planet imagers on 8–10 m class telescopes.

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