scholarly journals On the structure and evolution of planets and their host stars – effects of various heating mechanisms on the size of giant gas planets

2014 ◽  
Vol 445 (4) ◽  
pp. 4395-4405 ◽  
Author(s):  
M. Yıldız ◽  
Z. Çelik Orhan ◽  
C. Kayhan ◽  
G. E. Turkoglu
Keyword(s):  
Host Stars ◽  
Gas Planets

scholarly journals Confirming known planetary trends using a photometrically selected Kepler sample

2020 ◽  
Author(s):  
Jonah T Hansen ◽  
Luca Casagrande ◽  
Michael J Ireland ◽  
Jane Lin
Keyword(s):  
Sample Size ◽  
Robust Statistics ◽  
Narrow Band ◽  
Small Sample Size ◽  
Small Sample ◽  
Fitting Algorithm ◽  
Statistical Studies ◽  
The Rich ◽  
Host Stars ◽  
High Metallicity

Abstract Statistical studies of exoplanets and the properties of their host stars have been critical to informing models of planet formation. Numerous trends have arisen in particular from the rich Kepler dataset, including that exoplanets are more likely to be found around stars with a high metallicity and the presence of a “gap” in the distribution of planetary radii at 1.9 R⊕. Here we present a new analysis on the Kepler field, using the APOGEE spectroscopic survey to build a metallicity calibration based on Gaia, 2MASS and Strömgren photometry. This calibration, along with masses and radii derived from a Bayesian isochrone fitting algorithm, is used to test a number of these trends with unbiased, photometrically derived parameters, albeit with a smaller sample size in comparison to recent studies. We recover that planets are more frequently found around higher metallicity stars; over the entire sample, planetary frequencies are 0.88 ± 0.12 percent for [Fe/H] < 0 and 1.37 ± 0.16 percent for [Fe/H] ≥ 0 but at two sigma we find that the size of exoplanets influences the strength of this trend. We also recover the planet radius gap, along with a slight positive correlation with stellar mass. We conclude that this method shows promise to derive robust statistics of exoplanets. We also remark that spectrophotometry from Gaia DR3 will have an effective resolution similar to narrow band filters and allow to overcome the small sample size inherent in this study.

scholarly journals Estimation of singly transiting K2 planet periods with Gaia parallaxes

2019 ◽  
Vol 489 (3) ◽  
pp. 3149-3161 ◽  
Author(s):  
Emily Sandford ◽  
Néstor Espinoza ◽  
Rafael Brahm ◽  
Andrés Jordán
Keyword(s):  
Direct Measurement ◽  
Free Parameter ◽  
Broad Band ◽  
Long Period ◽  
Period Distribution ◽  
Typical Period ◽  
Stellar Models ◽  
Host Stars ◽  
Stellar Density ◽  
As If

ABSTRACT When a planet is only observed to transit once, direct measurement of its period is impossible. It is possible, however, to constrain the periods of single transiters, and this is desirable as they are likely to represent the cold and far extremes of the planet population observed by any particular survey. Improving the accuracy with which the period of single transiters can be constrained is therefore critical to enhance the long-period planet yield of surveys. Here, we combine Gaia parallaxes with stellar models and broad-band photometry to estimate the stellar densities of K2 planet host stars, then use that stellar density information to model individual planet transits and infer the posterior period distribution. We show that the densities we infer are reliable by comparing with densities derived through asteroseismology, and apply our method to 27 validation planets of known (directly measured) period, treating each transit as if it were the only one, as well as to 12 true single transiters. When we treat eccentricity as a free parameter, we achieve a fractional period uncertainty over the true single transits of $94^{+87}_{-58}{{\ \rm per\ cent}}$, and when we fix e = 0, we achieve fractional period uncertainty $15^{+30}_{-6}{{\ \rm per\ cent}}$, a roughly threefold improvement over typical period uncertainties of previous studies.

scholarly journals The homogeneous characterisation of Ariel host stars

2021 ◽  
Author(s):  
Camilla Danielski ◽  
Anna Brucalassi ◽  
Serena Benatti ◽  
Tiago Campante ◽  
Elisa Delgado-Mena ◽  
...  
Keyword(s):  
Host Stars

The Combined System of Microlensing Exoplanets and Their Host Stars

2018 ◽  
pp. 1641-1653
Author(s):  
Uffe Gråe Jørgensen ◽  
Markus Hundertmark
Keyword(s):  
Combined System ◽  
Host Stars

scholarly journals On the alignment of debris discs and their host stars’ rotation axis - implications for spin-orbit misalignment in exoplanetary systems

2011 ◽  
Vol 413 (1) ◽  
pp. L71-L75 ◽  
Author(s):  
C. A. Watson ◽  
S. P. Littlefair ◽  
C. Diamond ◽  
A. Collier Cameron ◽  
A. Fitzsimmons ◽  
...  
Keyword(s):  
Rotation Axis ◽  
Spin Orbit ◽  
Exoplanetary Systems ◽  
Host Stars

scholarly journals Stellar wind effects on the atmospheres of close-in giants: a possible reduction in escape instead of increased erosion

2020 ◽  
Vol 494 (2) ◽  
pp. 2417-2428 ◽  
Author(s):  
A A Vidotto ◽  
A Cleary
Keyword(s):  
Parameter Space ◽  
Stellar Wind ◽  
Planetary Atmospheres ◽  
External Pressure ◽  
Stellar Winds ◽  
Wind Effects ◽  
Atmospheric Escape ◽  
Large Pressure ◽  
Ram Pressure ◽  
Host Stars

ABSTRACT The atmospheres of highly irradiated exoplanets are observed to undergo hydrodynamic escape. However, due to strong pressures, stellar winds can confine planetary atmospheres, reducing their escape. Here, we investigate under which conditions atmospheric escape of close-in giants could be confined by the large pressure of their host star’s winds. For that, we simulate escape in planets at a range of orbital distances ([0.04, 0.14] au), planetary gravities ([36, 87 per cent] of Jupiter’s gravity), and ages ([1, 6.9] Gyr). For each of these simulations, we calculate the ram pressure of these escaping atmospheres and compare them to the expected stellar wind external pressure to determine whether a given atmosphere is confined or not. We show that although younger close-in giants should experience higher levels of atmospheric escape, due to higher stellar irradiation, stellar winds are also stronger at young ages, potentially reducing escape of young exoplanets. Regardless of the age, we also find that there is always a region in our parameter space where atmospheric escape is confined, preferably occurring at higher planetary gravities and orbital distances. We investigate confinement of some known exoplanets and find that the atmosphere of several of them, including π Men c, should be confined by the winds of their host stars, thus potentially preventing escape in highly irradiated planets. Thus, the lack of hydrogen escape recently reported for π Men c could be caused by the stellar wind.

Silicon and Nickel Enrichment in Planet Host Stars: Observations and Implications for the Core Accretion Theory of Planet Formation

2006 ◽  
Vol 643 (1) ◽  
pp. 484-500 ◽  
Author(s):  
Sarah E. Robinson ◽  
Gregory Laughlin ◽  
Peter Bodenheimer ◽  
Debra Fischer
Keyword(s):  
Planet Formation ◽  
The Core ◽  
Core Accretion ◽  
Host Stars ◽  
Nickel Enrichment

scholarly journals Spectroscopic [Fe/H] for 98 extra-solar planet-host stars

2004 ◽  
Vol 415 (3) ◽  
pp. 1153-1166 ◽  
Author(s):  
N. C. Santos ◽  
G. Israelian ◽  
M. Mayor
Keyword(s):  
Host Stars

scholarly journals Search for stellar companions of exoplanet host stars by exploring the second ESA-Gaia data release

2019 ◽  
Vol 490 (4) ◽  
pp. 5088-5102 ◽  
Author(s):  
M Mugrauer
Keyword(s):  
Main Sequence ◽  
Stellar Systems ◽  
Sequence Evolution ◽  
The Sun ◽  
M Dwarfs ◽  
Primary Star ◽  
True Nature ◽  
Quadruple System ◽  
Data Release ◽  
Host Stars

ABSTRACT A new survey is presented, which explores the second data release of the ESA-Gaia mission, in order to search for stellar companions of exoplanet host stars, located at distances closer than about 500 pc around the Sun. In total, 176 binaries, 27 hierarchical triples, and one hierarchical quadruple system are detected among more than 1300 exoplanet host stars, whose multiplicity is investigated, yielding a multiplicity rate of the exoplanet host stars of at least about 15  per cent. The detected companions and the exoplanet host stars are equidistant and share a common proper motion, as it is expected for gravitationally bound stellar systems, proven with their accurate Gaia astrometry. The companions exhibit masses in the range between about 0.078 and 1.4 M⊙ with a peak in their mass distribution between 0.15 and $0.3\, \mathrm{M}_{\odot }$. The companions are separated from the exoplanet host stars by about 20 up to 9100 au, but are found most frequently within a projected separation of 1000 au. While most of the detected companions are early M dwarfs, eight white dwarf companions of exoplanet host stars are also identified in this survey, whose true nature is revealed with their photometric properties. Hence, these degenerated companions and the exoplanet host stars form evolved stellar systems with exoplanets, which have survived (physically but also dynamically) the post-main-sequence evolution of their former primary star.

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