scholarly journals Mass-Metallicity Trends in Transiting Exoplanets from Atmospheric Abundances of H2O, Na, and K

2020 ◽  
Author(s):  
Luis Welbanks ◽  
Nikku Madhusudhan ◽  
Nicole F. Allard ◽  
Ivan Hubeny ◽  
Fernand Spiegelman ◽  
...  
Keyword(s):  
Solar System ◽  
Free Parameter ◽  
Giant Planets ◽  
The Other ◽  
Formation Mechanisms ◽  
Transmission Spectra ◽  
Low Oxygen ◽  
Hot Jupiters ◽  
Hot Gas ◽  
And Migration

<p>Atmospheric compositions can provide powerful diagnostics of formation and migration histories of planetary systems. In this talk, I will present the results of our latest survey of atmospheric compositions focused on atmospheric abundances of H<sub>2</sub>O, Na, and K. We employ a sample of 19 exoplanets spanning from cool mini-Neptunes to hot Jupiters, with equilibrium temperatures between ~300 and 2700 K. We employ the latest transmission spectra, new H<sub>2</sub> broadened opacities of Na and K, and homogeneous Bayesian retrievals. We confirm detections of H<sub>2</sub>O in 14 planets and detections of Na and K in 6 planets each. Among our sample, we find a mass-metallicity trend of increasing H<sub>2</sub>O abundances with decreasing mass, spanning generally substellar values for gas giants and stellar/superstellar for Neptunes and mini-Neptunes. However, the overall trend in H<sub>2</sub>O abundances, is significantly lower than the mass-metallicity relation for carbon in the solar system giant planets and similar predictions for exoplanets. On the other hand, the Na and K abundances for the gas giants are stellar or superstellar, consistent with each other, and generally consistent with the solar system metallicity trend. The H<sub>2</sub>O abundances in hot gas giants are likely due to low oxygen abundances relative to other elements rather than low overall metallicities, and provide new constraints on their formation mechanisms. Our results show that the differing trends in the abundances of species argue against the use of chemical equilibrium models with metallicity as one free parameter in atmospheric retrievals, as different elements can be differently enhanced.</p>

scholarly journals Cool Jupiters greatly outnumber their toasty siblings: occurrence rates from the Anglo-Australian Planet Search

2019 ◽  
Vol 492 (1) ◽  
pp. 377-383 ◽  
Author(s):  
Robert A Wittenmyer ◽  
Songhu Wang ◽  
Jonathan Horner ◽  
R P Butler ◽  
C G Tinney ◽  
...  
Keyword(s):  
Solar System ◽  
Radial Velocity ◽  
Planetary System ◽  
Planetary Systems ◽  
Giant Planets ◽  
Occurrence Rate ◽  
Hot Jupiters ◽  
The Past ◽  
Order Of Magnitude

ABSTRACT Our understanding of planetary systems different to our own has grown dramatically in the past 30 yr. However, our efforts to ascertain the degree to which the Solar system is abnormal or unique have been hindered by the observational biases inherent to the methods that have yielded the greatest exoplanet hauls. On the basis of such surveys, one might consider our planetary system highly unusual – but the reality is that we are only now beginning to uncover the true picture. In this work, we use the full 18-yr archive of data from the Anglo-Australian Planet Search to examine the abundance of ‘cool Jupiters’ – analogues to the Solar system’s giant planets, Jupiter and Saturn. We find that such planets are intrinsically far more common through the cosmos than their siblings, the hot Jupiters. We find that the occurrence rate of such ‘cool Jupiters’ is $6.73^{+2.09}_{-1.13}$ per cent, almost an order of magnitude higher than the occurrence of hot Jupiters (at $0.84^{+0.70}_{-0.20}$ per cent). We also find that the occurrence rate of giant planets is essentially constant beyond orbital distances of ∼1 au. Our results reinforce the importance of legacy radial velocity surveys for the understanding of the Solar system’s place in the cosmos.

scholarly journals Timing of the formation and migration of giant planets as constrained by CB chondrites

2016 ◽  
Vol 2 (12) ◽  
pp. e1601658 ◽  
Author(s):  
Brandon C. Johnson ◽  
Kevin J. Walsh ◽  
David A. Minton ◽  
Alexander N. Krot ◽  
Harold F. Levison
Keyword(s):  
Solar System ◽  
Solar Nebula ◽  
Giant Planet ◽  
Planetary Systems ◽  
Early Time ◽  
High Impact ◽  
Giant Planets ◽  
Significant Fraction ◽  
Carbonaceous Chondrites ◽  
And Migration

The presence, formation, and migration of giant planets fundamentally shape planetary systems. However, the timing of the formation and migration of giant planets in our solar system remains largely unconstrained. Simulating planetary accretion, we find that giant planet migration produces a relatively short-lived spike in impact velocities lasting ~0.5 My. These high-impact velocities are required to vaporize a significant fraction of Fe,Ni metal and silicates and produce the CB (Bencubbin-like) metal-rich carbonaceous chondrites, a unique class of meteorites that were created in an impact vapor-melt plume ~5 My after the first solar system solids. This indicates that the region where the CB chondrites formed was dynamically excited at this early time by the direct interference of the giant planets. Furthermore, this suggests that the formation of the giant planet cores was protracted and the solar nebula persisted until ~5 My.

scholarly journals A multiplicity study of transiting exoplanet host stars

2020 ◽  
Vol 635 ◽  
pp. A73 ◽  
Author(s):  
A. J. Bohn ◽  
J. Southworth ◽  
C. Ginski ◽  
M. A. Kenworthy ◽  
P. F. L. Maxted ◽  
...  
Keyword(s):  
Proper Motion ◽  
Angular Separation ◽  
Current Data ◽  
Formation Mechanisms ◽  
Multiple Systems ◽  
Hot Jupiters ◽  
Data Release ◽  
And Migration ◽  
Almost All ◽  
Host Stars

Context. Many main-sequence stars are part of multiple systems. The effect of stellar multiplicity on planet formation and migration, however, is poorly understood. Aims. We study the multiplicity of stars hosting known transiting extra-solar planets to test competing theories on the formation mechanisms of hot Jupiters. Methods. We observed 45 exoplanet host stars using the infrared dual imaging spectrograph of the Spectro-Polarimetric High-Contrast Exoplanet Research (SPHERE) instrument at the Very Large Telescope to search for potential companions. For each identified candidate companion we determined the probability that it is gravitationally bound to its host by performing common proper motion checks and modelling of synthetic stellar populations around the host. In addition, we derived contrast limits as a function of angular separation to set upper limits on further companions in these systems. We converted the derived contrast into mass thresholds using AMES-Cond, AMES-Dusty, and BT-Settl models. Results. We detected new candidate companions around K2-38, WASP-72, WASP-80, WASP-87, WASP-88, WASP-108, WASP-118, WASP-120, WASP-122, WASP123, WASP-130, WASP-131, and WASP-137. The closest candidates were detected at separations of 0.′′124±0.′′007 and 0.′′189±0.′′003 around WASP-108 and WASP-131; the measured K-band contrasts indicate that these are stellar companions of 0.35 ± 0.02 M⊙ and 0.62−0.04+0.05 M⊙, respectively. Including the re-detection and confirmation of previously known companions in 13 other systems, we derived a multiplicity fraction of 55.4−9.4+5.9%. For the representative sub-sample of 40 hot Jupiter host stars among our targets, the derived multiplicity rate is 54.8−9.9+6.3%. Our data do not confirm any trend that systems with eccentric planetary companions are preferably part of multiple systems. On average, we reached a magnitude contrast of 8.5 ± 0.9 mag at an angular separation of 0.′′5. This allows us to exclude additional stellar companions with masses higher than 0.08M⊙ for almost all observed systems; around the closest and youngest systems, this sensitivity is achieved at physical separations as small as 10 au. Conclusions. Our study shows that SPHERE is an ideal instrument for detecting and characterising close companions to exoplanetary host stars. Although the second data release of the Gaia mission also provides useful constraints for some of the systems, the achieved sensitivity provided by the current data release of this mission is not good enough to measure parallaxes and proper motions for all detected candidates. For 14 identified companion candidates further astrometric epochs are required to confirm their common proper motion at 5σ significance.

scholarly journals Chemical fingerprints of hot Jupiter planet formation

2018 ◽  
Vol 612 ◽  
pp. A93 ◽  
Author(s):  
J. Maldonado ◽  
E. Villaver ◽  
C. Eiroa
Keyword(s):  
Planet Formation ◽  
Statistical Tests ◽  
Giant Planets ◽  
Volatile Elements ◽  
Hot Jupiters ◽  
Chemical Fingerprints ◽  
Gas Giant ◽  
Orbital Periods ◽  
And Migration

Context. The current paradigm to explain the presence of Jupiter-like planets with small orbital periods (P < 10 days; hot Jupiters), which involves their formation beyond the snow line following inward migration, has been challenged by recent works that explore the possibility of in situ formation. Aims. We aim to test whether stars harbouring hot Jupiters and stars with more distant gas-giant planets show any chemical peculiarity that could be related to different formation processes. Methods. Our methodology is based on the analysis of high-resolution échelle spectra. Stellar parameters and abundances of C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, and Zn for a sample of 88 planet hosts are derived. The sample is divided into stars hosting hot (a < 0.1 au) and cool (a > 0.1 au) Jupiter-like planets. The metallicity and abundance trends of the two sub-samples are compared and set in the context of current models of planet formation and migration. Results. Our results show that stars with hot Jupiters have higher metallicities than stars with cool distant gas-giant planets in the metallicity range +0.00/+0.20 dex. The data also shows a tendency of stars with cool Jupiters to show larger abundances of α elements. No abundance differences between stars with cool and hot Jupiters are found when considering iron peak, volatile elements or the C/O, and Mg/Si ratios. The corresponding p-values from the statistical tests comparing the cumulative distributions of cool and hot planet hosts are 0.20, <0.01, 0.81, and 0.16 for metallicity, α, iron-peak, and volatile elements, respectively. We confirm previous works suggesting that more distant planets show higher planetary masses as well as larger eccentricities. We note differences in age and spectral type between the hot and cool planet host samples that might affect the abundance comparison. Conclusions. The differences in the distribution of planetary mass, period, eccentricity, and stellar host metallicity suggest a different formation mechanism for hot and cool Jupiters. The slightly larger α abundances found in stars harbouring cool Jupiters might compensate their lower metallicities allowing the formation of gas-giant planets.

scholarly journals Connecting planet formation and astrochemistry

2019 ◽  
Vol 627 ◽  
pp. A127 ◽  
Author(s):  
Alexander J. Cridland ◽  
Christian Eistrup ◽  
Ewine F. van Dishoeck
Keyword(s):  
Solar System ◽  
Planet Formation ◽  
Chemical Kinetic ◽  
Total Carbon ◽  
Dust Grains ◽  
Excess Carbon ◽  
Hot Jupiters ◽  
And Migration ◽  
Grain Surface ◽  
Carbon Excess

Combining a time-dependent astrochemical model with a model of planet formation and migration, we compute the carbon-to-oxygen ratio (C/O) of a range of planetary embryos starting their formation in the inner solar system (1–3 AU). Most of the embryos result in hot Jupiters (M ≥ MJ, orbital radius <0.1 AU) while the others result in super-Earths at wider orbital radii. The volatile and ice abundance of relevant carbon and oxygen bearing molecular species are determined through a complex chemical kinetic code that includes both gas and grain surface chemistry. This is combined with a model for the abundance of the refractory dust grains to compute the total carbon and oxygen abundance in the protoplanetary disk available for incorporation into a planetary atmosphere. We include the effects of the refractory carbon depletion that has been observed in our solar system, and posit two models that would put this missing carbon back into the gas phase. This excess gaseous carbon then becomes important in determining the final planetary C/O because the gas disk now becomes more carbon rich relative to oxygen (high gaseous C/O). One model, where the carbon excess is maintained throughout the lifetime of the disk results in hot Jupiters that have super-stellar C/O. The other model deposits the excess carbon early in the disk life and allows it to advect with the bulk gas. In this model the excess carbon disappears into the host star within 0.8 Myr, returning the gas disk to its original (substellar) C/O, so the hot Jupiters all exclusively have substellar C/O. This shows that while the solids tend to be oxygen rich, hot Jupiters can have super-stellar C/O if a carbon excess can be maintained by some chemical processing of the dust grains. The atmospheric C/O of the super-Earths at larger radii are determined by the chemical interactions between the gas and ice phases of volatile species rather than the refractory carbon model. Whether the carbon and oxygen content of the atmosphere was accreted primarily by gas or solid accretion is heavily dependent on the mass of the atmosphere and where in the disk the growing planet accreted.

scholarly journals The properties of super-Earth atmospheres

2010 ◽  
Vol 6 (S276) ◽  
pp. 212-217 ◽  
Author(s):  
Eliza M. R. Kempton
Keyword(s):  
Solar System ◽  
Bulk Composition ◽  
Theoretical Work ◽  
Giant Planets ◽  
The Other ◽  
Terrestrial Planets ◽  
Earth Atmosphere ◽  
Intermediate Mass ◽  
Rocky Planets

AbstractExtrasolar super-Earths likely have a far greater diversity in their atmospheric properties than giant planets. Super-Earths (planets with masses between 1 and 10 M⊕) lie in an intermediate mass regime between gas/ice giants like Neptune and rocky terrestrial planets like Earth and Venus. While some super-Earths (especially the more massive ones) may retain large amounts of hydrogen either from accretion processes or subsequent surface outgassing, other super-Earths should have atmospheres composed of predominantly heavier molecules, similar to the atmospheres of the rocky planets and moons of our Solar System. Others still may be entirely stripped of their atmospheres and remain as bare rocky cores. Of the two currently known transiting super-Earths one (GJ 1214b) likely falls into the former category with a thick atmosphere, while the other (CoRoT-7b) falls into the latter category with a very thin or nonexistent atmosphere. I review some of the theoretical work on super-Earth atmospheres, and I present methods for determining the bulk composition of a super-Earth atmosphere.

Two Gambling Women

2012 ◽  
Vol 5 (1) ◽  
pp. 39-49
Author(s):  
Tzu-Hui Chen
Keyword(s):  
Lived Experiences ◽  
Personal Experience ◽  
Cultural Context ◽  
Cross Cultural ◽  
Immigrant Population ◽  
The Other ◽  
Mail Order ◽  
Foreign Brides ◽  
And Migration ◽  
The Relationship

This narrative aims to explore the meaning and lived experiences of marriage that a unique immigrant population—“foreign brides” in Taiwan—possesses. This convergence narrative illustrates the dynamics and complexity of mail-order marriage and women's perseverance in a cross-cultural context. The relationship between marriage, race, and migration is analyzed. This narrative is comprised of and intertwined by two story lines. One is the story of two “foreign brides” in Taiwan. The other is my story about my cross-cultural relationship. All the dialogues are generated by 25 interviews of “foreign brides” in Taiwan and my personal experience.

The Long View of Planetary Systems

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Milky Way ◽  
Planetary Systems ◽  
Giant Planets ◽  
Milky Way Galaxy ◽  
Population Statistics ◽  
The Past ◽  
General Terms ◽  
The Galaxy ◽  
The Universe

How many planetary systems formed before our’s did, and how many will form after? How old is the average exoplanet in the Galaxy? When did the earliest planets start forming? How different are the ages of terrestrial and giant planets? And, ultimately, what will the fate be of our Solar System, of the Milky Way Galaxy, and of the Universe around us? We cannot know the fate of individual exoplanets with great certainty, but based on population statistics this chapter sketches the past, present, and future of exoworlds and of our Earth in general terms.

scholarly journals In Situ exploration of the giant planets

2021 ◽  
Author(s):  
O. Mousis ◽  
D. H. Atkinson ◽  
R. Ambrosi ◽  
S. Atreya ◽  
D. Banfield ◽  
...  
Keyword(s):  
Solar System ◽  
Giant Planets ◽  
Atmospheric Composition ◽  
Formation History ◽  
History Of ◽  
Composition Structure ◽  
Galileo Probe ◽  
Probe Measurements

AbstractRemote sensing observations suffer significant limitations when used to study the bulk atmospheric composition of the giant planets of our Solar System. This impacts our knowledge of the formation of these planets and the physics of their atmospheres. A remarkable example of the superiority of in situ probe measurements was illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases’ abundances and the precise measurement of the helium mixing ratio were only made available through in situ measurements by the Galileo probe. Here we describe the main scientific goals to be addressed by the future in situ exploration of Saturn, Uranus, and Neptune, placing the Galileo probe exploration of Jupiter in a broader context. An atmospheric entry probe targeting the 10-bar level would yield insight into two broad themes: i) the formation history of the giant planets and that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. An atmospheric probe could represent a significant ESA contribution to a future NASA New Frontiers or flagship mission to be launched toward Saturn, Uranus, and/or Neptune.

scholarly journals The Grand Tack model: a critical review

2014 ◽  
Vol 9 (S310) ◽  
pp. 194-203 ◽  
Author(s):  
Sean N. Raymond ◽  
Alessandro Morbidelli
Keyword(s):  
Solar System ◽  
Building Blocks ◽  
Protoplanetary Disk ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Terrestrial Planets ◽  
Saturn’S Satellites ◽  
Internal Inconsistency ◽  
Solar System Bodies ◽  
Gas Accretion

AbstractThe “Grand Tack” model proposes that the inner Solar System was sculpted by the giant planets' orbital migration in the gaseous protoplanetary disk. Jupiter first migrated inward then Jupiter and Saturn migrated back outward together. If Jupiter's turnaround or “tack” point was at ~ 1.5 AU the inner disk of terrestrial building blocks would have been truncated at ~ 1 AU, naturally producing the terrestrial planets' masses and spacing. During the gas giants' migration the asteroid belt is severely depleted but repopulated by distinct planetesimal reservoirs that can be associated with the present-day S and C types. The giant planets' orbits are consistent with the later evolution of the outer Solar System.Here we confront common criticisms of the Grand Tack model. We show that some uncertainties remain regarding the Tack mechanism itself; the most critical unknown is the timing and rate of gas accretion onto Saturn and Jupiter. Current isotopic and compositional measurements of Solar System bodies – including the D/H ratios of Saturn's satellites – do not refute the model. We discuss how alternate models for the formation of the terrestrial planets each suffer from an internal inconsistency and/or place a strong and very specific requirement on the properties of the protoplanetary disk.We conclude that the Grand Tack model remains viable and consistent with our current understanding of planet formation. Nonetheless, we encourage additional tests of the Grand Tack as well as the construction of alternate models.

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