Conservation laws and mass distribution in the planet formation process

The Moon ◽  
1977 ◽  
Vol 17 (4) ◽  
pp. 401-408 ◽  
Author(s):  
Paolo Farinella ◽  
Paolo Paolicchi
Keyword(s):  
Conservation Laws ◽  
Mass Distribution ◽  
Formation Process ◽  
Planet Formation

Planet formation process as a phase transition

1979 ◽  
Vol 20 (4) ◽  
pp. 371-384 ◽  
Author(s):  
Paolo Farinella ◽  
Paolo Paolicchi ◽  
Federico Ferrini
Keyword(s):  
Phase Transition ◽  
Formation Process ◽  
Planet Formation

scholarly journals ALMA survey of Class II protoplanetary disks in Corona Australis: a young region with low disk masses

2019 ◽  
Vol 626 ◽  
pp. A11 ◽  
Author(s):  
P. Cazzoletti ◽  
C. F. Manara ◽  
H. Baobab Liu ◽  
E. F. van Dishoeck ◽  
S. Facchini ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Mass Distribution ◽  
Planet Formation ◽  
Protoplanetary Disks ◽  
Class Ii ◽  
Star Forming ◽  
Star Forming Regions ◽  
Disk Mass ◽  
Intrinsic Angular Momentum ◽  
Dust Mass

Context. In recent years, the disk populations in a number of young star-forming regions have been surveyed with the Atacama Large Millimeter/submillimeter Array (ALMA). Understanding the disk properties and their correlation with the properties of the central star is critical to understanding planet formation. In particular, a decrease of the average measured disk dust mass with the age of the region has been observed, consistent with grain growth and disk dissipation. Aims. We aim to compare the general properties of disks and their host stars in the nearby (d = 160 pc) Corona Australis (CrA) star forming region to those of the disks and stars in other regions. Methods. We conducted high-sensitivity continuum ALMA observations of 43 Class II young stellar objects in CrA at 1.3 mm (230 GHz). The typical spatial resolution is ~0.3′′. The continuum fluxes are used to estimate the dust masses of the disks, and a survival analysis is performed to estimate the average dust mass. We also obtained new VLT/X-shooter spectra for 12 of the objects in our sample for which spectral type (SpT) information was missing. Results. Twenty-four disks were detected, and stringent limits have been put on the average dust mass of the nondetections. Taking into account the upper limits, the average disk mass in CrA is 6 ± 3 M⊕. This value is significantly lower than that of disks in other young (1–3 Myr) star forming regions (Lupus, Taurus, Chamaeleon I, and Ophiuchus) and appears to be consistent with the average disk mass of the 5–10 Myr-old Upper Sco. The position of the stars in our sample on the Herzsprung-Russel diagram however seems to confirm that CrA has an age similar to Lupus. Neither external photoevaporation nor a lower-than-usual stellar mass distribution can explain the low disk masses. On the other hand, a low-mass disk population could be explained if the disks were small, which could happen if the parent cloud had a low temperature or intrinsic angular momentum, or if the angular momentum of the cloud were removed by some physical mechanism such as magnetic braking. Even in detected disks, none show clear substructures or cavities. Conclusions. Our results suggest that in order to fully explain and understand the dust mass distribution of protoplanetary disks and their evolution, it may also be necessary to take into consideration the initial conditions of star- and disk-formation process. These conditions at the very beginning may potentially vary from region to region, and could play a crucial role in planet formation and evolution.

scholarly journals Biased Galaxy Formation and Dark Matter

1988 ◽  
Vol 130 ◽  
pp. 437-446
Author(s):  
Martin J. Rees
Keyword(s):  
Dark Matter ◽  
Cosmological Model ◽  
Mass Distribution ◽  
Galaxy Formation ◽  
Formation Process ◽  
Large Scale

The clustering properties of galaxies are incompatible with a cosmological model with Ω = 1 unless the formation process for bright galaxies is ‘biased’ in the sense that their resultant distribution exaggerates the amplitude of large-scale inhomogeneities in the overall mass distribution. The mechanisms for such biasing are intimately connected with the nature of the dark matter. Various possibilities are summarised here.

scholarly journals “The mass distribution of the young stellar population in Chamaeleon I and in Rho Ophiuchi”

1991 ◽  
Vol 147 ◽  
pp. 427-429
Author(s):  
Jane C. Gregório Hetem ◽  
J.R.D. Lépine ◽  
R. Ortiz
Keyword(s):  
Star Formation ◽  
Mass Distribution ◽  
Formation Process ◽  
Stellar Population ◽  
Age Distribution ◽  
Young Stars ◽  
Rho Ophiuchi ◽  
Hr Diagram

We obtain the mass distribution and the age distribution of the young stars associated with Chamaeleon I and Rho Ophiuchi, two nearby sites of star formation. Our method consists in determining the temperature and the luminosity of each object in order to locate it on the HR diagram, and then comparing the position on the HR diagram with the evolutionary tracks and isochrones presented by Cohen and Kuhi (1979). The star-formation process is found to have started more recently in ρ Oph than in Cham I.

The origin of the obliquity in planetary systems studied with infrared interferometry

2020 ◽  
Author(s):  
Stefan Kraus
Keyword(s):  
Formation Process ◽  
Planet Formation ◽  
Rotation Axis ◽  
Scattered Light ◽  
Dynamical Evolution ◽  
Asymmetric Structure ◽  
Stellar Rotation ◽  
3 Dimensional ◽  
Beam Combination ◽  
Infrared Interferometry

<p>Observations of the Rossiter-McLaughlin effect have revealed that the orbits of many exoplanets are misaligned with respect to the stellar rotation axis. Various scenarios have been proposed that associate the orbit obliquity either with multi-body interactions or dynamical processes in the disc during the planet formation process. In this talk, I will present how infrared interferometry allows us to study the origin of the planet obliquity:</p> <p>In the first part of the talk I will present observations that reveal the recently-posted disc tearing effect, where the gravitational torque of companions on misaligned orbits can tear the disc apart into distinct rings that precess independently around the central objects. We imaged the triple system GW Orionis using VLTI, CHARA, ALMA, SPHERE, and GPI and discover three rings in thermal light and an asymmetric structure with radial shadows in scattered light. The inner-most ring is eccentric (e=0.3; 43 au radius) and strongly misaligned both with respect to the orbital planes and with respect to the outer disc. Modelling the scattered light signatures and the shape of the shadows cast by the misaligned ring allows us derive the shape and 3-dimensional orientation of the disc surface, revealing that the disc is strongly warped and breaks at a radius of about 50 au. Based on the measured triple star orbits and disc properties, we conducted smoothed particle hydrodynamic simulations which show that the system is susceptible to the disc tearing effect. The ring offers suitable conditions for planet formation, providing a mechanism for forming wide-separation planets on highly oblique orbits. Our results imply that there may exist a significant, yet undiscovered population of long-period planets on highly oblique orbits that has formed around misaligned multiple systems.</p> <p>In the second part I will show how infrared interferometry can be used to search for this predicted population of wide-separation planets on oblique orbits, probing a highly complementary regime to the parameter space accessible with the Rossiter-McLaughlin effect. I will present the first study where the spin-orbit alignment has been measured for a directly-imaged exoplanet, namely on Beta Pictoris b. We used VLTI/GRAVITY spectro-interferometry with an astrometric accuracy of 1 microarcsecond to measure the photocenter displacement associated with the stellar rotation. Taking inclination constraints from astroseismology into account, we constrain the 3-dimensional orientation of the stellar spin axis and find that Beta Pic b orbits its host star on a prograde orbit with a small obliquity angle. </p> <p>I will conclude by offering a near-term perspective on how infrared interferometry with the proposed BIFROST beam-combination instrument could advance our understanding of the planet formation process and of the early dynamical evolution of exoplanetary systems.</p>

scholarly journals Carbon-grain sublimation: a new top-down component to protostellar chemistry

2020 ◽  
Author(s):  
Merel van 't Hoff ◽  
Edwin Bergin ◽  
Jes Jorgensen ◽  
Geoffrey Blake
Keyword(s):  
Gas Phase ◽  
Formation Process ◽  
Organic Molecules ◽  
Planet Formation ◽  
Protoplanetary Disks ◽  
Excitation Temperature ◽  
Top Down ◽  
Carbon Chemistry ◽  
Episodic Nature ◽  
Protosolar Nebula

<p>One of the main goals in the fields of exoplanets and planet formation is to determine the composition of terrestrial, potentially habitable, planets and to link this to the composition of protoplanetary disks. A longstanding puzzle in this regard is the Earth's severe carbon deficit; Earth is 2-4 orders of magnitude depleted in carbon compared to interstellar grains and comets. The solution to this conundrum is that carbon must have been returned to the gas phase in the inner protosolar nebula, such that it could not get accreted onto the forming bodies. A process that could be responsible is the sublimation of carbon grains at the so-called soot line (~300 K) early in the planet-formation process. I will argue that the most likely signatures of this process are an excess of hydrocarbons and nitriles inside the soot line around protostars, and a higher excitation temperature for these molecules compared to oxygen-bearing complex organics that desorb around the water snowline (~100 K). Moreover, I will show that such characteristics have indeed been reported in the literature, for example, in Orion KL, although not uniformly, potentially due to differences in observational settings or related to the episodic nature of protostellar accretion. If this process is active, this would mean that there is an heretofore unrecognized component to the carbon chemistry during the protostellar phase that is acting from the top down - starting from the destruction of larger species - instead of from the bottom up from atoms. In the presence of such a top-down component, the origin of organic molecules needs to be re-explored. </p>

scholarly journals Color Dependence of Planetary Transit Depths due to Large Starspots and Dust Clouds: Application to PTFO 8-8695

2021 ◽  
Vol 5 (11) ◽  
pp. 264
Author(s):  
Theodore A. Grosson ◽  
Christopher M. Johns-Krull
Keyword(s):  
Formation Process ◽  
Direct Evidence ◽  
Planet Formation ◽  
Dust Clouds ◽  
Multiple Wavelengths ◽  
Infrared Wavelengths ◽  
Planetary Transits

Abstract Although thousands of exoplanets have now been discovered, there is still a significant lack of observations of young planets only a few Myr old. Thus there is little direct evidence available to differentiate between various models of planet formation. The detection of planets of this age would provide much-needed data that could help constrain the planet formation process. To explore what transit observations of such planets may look like, we model the effects of large starspots and dust clouds on the depths of exoplanet transits across multiple wavelengths. We apply this model to the candidate planet PTFO 8-8695b, whose depths vary significantly across optical and infrared wavelengths. Our model shows that, while large starspots can significantly increase the color dependence of planetary transits, a combination of starspots and a large cloud surrounding the planet is required to reproduce the observed transit depths across four wavelengths.

Mass Distribution and Planet Formation in the Solar Nebula

2007 ◽  
Vol 671 (1) ◽  
pp. 878-893 ◽  
Author(s):  
S. J. Desch
Keyword(s):  
Mass Distribution ◽  
Planet Formation ◽  
Solar Nebula

scholarly journals On the origin of giant planets and their hosts

2009 ◽  
Vol 5 (S265) ◽  
pp. 434-435
Author(s):  
Misha Haywood
Keyword(s):  
Formation Process ◽  
Planet Formation ◽  
Galactic Disk ◽  
Giant Planet ◽  
Solar Radius ◽  
Thick Disk ◽  
Giant Planets ◽  
Dynamical Effect ◽  
Giant Stars ◽  
Metallicity Distribution

AbstractThe correlation between stellar metallicity and giant planets has been tentatively explained by the possible increase of planet formation probability in stellar disks with enhanced amount of metals. There are two caveats to this explanation. First, giant stars with planets do not show a metallicity distribution skewed towards metal-rich objects, as found for dwarfs. Second, the correlation with metallicity is not valid at intermediate metallicities, for which it can be shown that giant planets are preferentially found orbiting thick disk stars.None of these two peculiarities is explained by the proposed scenarios of giant planet formation. We contend that they are galactic in nature, and probably not linked to the formation process of giant planets. It is suggested that the same dynamical effect, namely the migration of stars in the galactic disk, is at the origin of both features, with the important consequence that most metal-rich stars hosting giant planets originate from the inner disk. A planet-metallicity correlation similar to the observed one is easily obtained if stars from the inner disk have a higher percentage of giant planets than stars born at the solar radius, with no specific dependence on metallicity. We propose that the density of H2 in the inner galactic disk (the molecular ring) could play a role in setting the high percentage of giant planets that originate from this region.

scholarly journals Giant planet formation — a theoretical timeline

2004 ◽  
Vol 202 ◽  
pp. 167-174 ◽  
Author(s):  
Günther Wuchterl
Keyword(s):  
Star Formation ◽  
Solar System ◽  
Formation Process ◽  
Planet Formation ◽  
Giant Planet ◽  
Circumstellar Disks ◽  
Giant Planets ◽  
Low Mass ◽  
Star Formation Regions ◽  
Observational Techniques

Low mass circumstellar disks are a result of the star formation process. The growth of dust and solid planets in such pre-planetary disks determines many properties of our solar system. Models of the Solar System giant planets indicate an enrichment of heavy elements and imply heavy element cores. Detailed models therefore describe giant planet formation as a consequence of the formation of solid planets that have grown sufficiently large to permanently bind gas from the protoplanetary nebula. The diversity of Solar System and extrasolar giant planets is explained by variations in the core growth rates caused by a coupling of the dynamics of planetesimals and the contraction of the massive envelopes they dive into, as well as by changes in the hydrodynamical accretion behavior of the envelopes resulting from differences in nebula density, temperature and orbital distance. Detailed formation models are able to determine observables as luminosities, radii and effective temperatures of young giant planets. Present observational techniques do now allow to probe star formation regions at ages covering all evolutionary stages of the giant planet formation process.

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