scholarly journals The Initial Conditions for Planet Formation: Turbulence Driven by Hydrodynamical Instabilities in Disks around Young Stars

2019 ◽  
Vol 131 (1001) ◽  
pp. 072001 ◽  
Author(s):  
Wladimir Lyra ◽  
Orkan M. Umurhan
Keyword(s):  
Planet Formation ◽  
Initial Conditions ◽  
Young Stars

scholarly journals Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): A close low-mass companion to ET Cha

2020 ◽  
Vol 642 ◽  
pp. A119
Author(s):  
C. Ginski ◽  
F. Ménard ◽  
Ch. Rab ◽  
E. E. Mamajek ◽  
R. G. van Holstein ◽  
...  
Keyword(s):  
Planet Formation ◽  
Thermal Emission ◽  
Initial Conditions ◽  
Scattered Light ◽  
Primary Component ◽  
Young Stars ◽  
High Contrast ◽  
Evolution Study ◽  
Disk Evolution ◽  
Low Mass

Context. To understand the formation of planetary systems, it is important to understand the initial conditions of planet formation, that is, the young gas-rich planet forming disks. Spatially resolved, high-contrast observations are of particular interest since substructures in disks that are linked to planet formation can be detected. In addition, we have the opportunity to reveal close companions or even planets in formation that are embedded in the disk. Aims. In this study, we present the first results of the Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS), an ESO/SPHERE large program that is aimed at studying disk evolution in scattered light, mainly focusing on a sample of low-mass stars (< 1 M⊙) in nearby (∼200 pc) star-forming regions. In this particular study, we present observations of the ET Cha (RECX 15) system, a nearby “old” classical T Tauri star (5−8 Myr, ∼100 pc), which is still strongly accreting. Methods. We used SPHERE/IRDIS in the H-band polarimetric imaging mode to obtain high spatial resolution and high-contrast images of the ET Cha system to search for scattered light from the circumstellar disk as well as thermal emission from close companions. We additionally employed VLT/NACO total intensity archival data of the system taken in 2003. Results. Here, we report the discovery, using SPHERE/IRDIS, of a low-mass (sub)stellar companion to the η Cha cluster member ET Cha. We estimate the mass of this new companion based on photometry. Depending on the system age, it is either a 5 Myr, 50 MJup brown dwarf or an 8 Myr, 0.10 M⊙ M-type, pre-main-sequence star. We explore possible orbital solutions and discuss the recent dynamic history of the system. Conclusions. Independent of the precise companion mass, we find that the presence of the companion likely explains the small size of the disk around ET Cha. The small separation of the binary pair indicates that the disk around the primary component is likely clearing from the outside in, which explains the high accretion rate of the system.

scholarly journals The Chemistry of Nearby Disks

2015 ◽  
Vol 10 (S314) ◽  
pp. 143-148
Author(s):  
Karin I. Öberg
Keyword(s):  
Planet Formation ◽  
Initial Conditions ◽  
Young Star ◽  
Young Stars ◽  
Chemical Structures ◽  
Lessons Learnt ◽  
Trace Species ◽  
Molecular Studies

AbstractThe gas and dust rich disks around young stars are the formation sites of planets. Observations of molecular trace species have great potential as probes of the disk structures and volatile compositions that together regulate planet formation. The disk around young star TW Hya has become a template for disk molecular studies due to a combination of proximity, a simple face-on geometry and richness in volatiles. It is unclear, however, how typical the chemistry of the TW disk is. In this proceeding, we review lessons learnt from exploring the TW Hya disk chemistry, focusing on the CO snowline, and on deuterium fractionation chemistry. We compare these results with new ALMA observations toward more distant, younger disks. We find that while all disks have some chemical structures in common, there are also substantial differences between the disks, which may be due to different initial conditions, structural or chemical evolutionary stages, or a combination of all three.

Exploring the dust ring in the circum-binary disc around GG Tau A

2021 ◽  
Author(s):  
Claudia Toci ◽  
Simone Ceppi ◽  
Nicolas Cuello ◽  
Giuseppe Lodato ◽  
Cristiano Longarini ◽  
...  
Keyword(s):  
Binary Systems ◽  
Planet Formation ◽  
Initial Conditions ◽  
Scattered Light ◽  
Complex Structure ◽  
Semimajor Axis ◽  
Continuum Emission ◽  
Orbital Parameter ◽  
Semi Major Axis ◽  
Multiple Systems

&lt;p&gt;Binaries and multiple systems are common among young stars (Reipurth et al. 2014). These stars are often surrounded by discs of gas and dust, formed due to the conservation of angular momentum of the collapsing cloud, thought to be the site of planet formation.&lt;br /&gt;In the case of binary systems, three discs can form: an outer disc surrounding all the stars (called circumbinary disc), and two inner discs around the stars. As circumbinary planets have recently been discovered by Kepler (see e.g., Martin 2018, Bonavita &amp; Desidera 2020), it is crucial to understand the dynamics and evolution of circumbinary discs to better understand the initial conditions of planet formation in multiple systems.&lt;br /&gt;The GG Tau A system is an example of a young multiple T Tauri star. The binary is surrounded by a bright disc, observed in the continuum emission at different wavelengths (see e.g., Guilloteau et al. 1999; Dutrey et al. 2014; Phuong et al. 2020b) and in scattered light (e.g., Duchene et al. 2014, Keppler et al. 2020). The disc extends in the dust from 180 to 280 au from the center of mass, and in the gas up to 850 au. The inner (&lt;180 au) part is depleted in gas and dust. Scattered light images show a complex structure in the inner part of the disc, with arcs and filamentary structures connecting the outer ring with the arcs and three shadows.&lt;br /&gt;Two different configurations are possible fitting the proper motion data for the system: a co-planar case with a low eccentricity binary with a semi-major axis of 34 au, explored by Cazzoletti et al. 2017 and Keppler et al. 2020, and a misaligned case (i=30) with an eccentric binary (e=0.45) and a wider semimajor axis of 60 au (Aly et al.2018). At the state of the art, all these analyses focused on the gas dynamics only.&lt;br /&gt;We will show the results of new 3D SPH simulations of dust and gas performed with the code PHANTOM, devised to test the two possible scenarios. We will describe the dynamics of the system in the two cases, comparing our models with observational results in order to better constraint the orbital parameter of the GG Tau A system. Our predictions will guide future observing campaigns and shed light on the complex evolution of discs in triple stellar systems.&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Probing AU-scale Structure using Spectro-astrometry

2004 ◽  
Vol 221 ◽  
pp. 417-424 ◽  
Author(s):  
Michihiro Takami ◽  
Jeremy Bailey ◽  
Antonio Chrysostomou ◽  
Motohide Tamura ◽  
Hiroshi Terada
Keyword(s):  
Adaptive Optics ◽  
Main Sequence ◽  
Planet Formation ◽  
Hubble Space Telescope ◽  
Circumstellar Disks ◽  
Scale Structure ◽  
Young Stars ◽  
Space Telescope ◽  
Powerful Technique ◽  
Circumstellar Environment

The circumstellar environment within 10 AU of young stars are of particular interest for star and planet formation. Unfortunately, present imaging facilities such as the Hubble Space Telescope or adaptive optics on 10-m telescopes cannot resolve this region. We have proved that “spectro-astrometry” is a powerful technique for discovering pre-main-sequence binaries, determining kinematics of outflows and providing evidence for gaps in circumstellar disks — all down to AU scales. In this paper, we summarise our progress to date.

scholarly journals An UXor among FUors: extinction-related brightness variations of the young eruptive star V582 Aur

2018 ◽  
Vol 14 (S345) ◽  
pp. 390-392
Author(s):  
P. Ábrahám ◽  
Á. Kóspál ◽  
M. Kun ◽  
O. Fehér ◽  
G. Zsidi ◽  
...  
Keyword(s):  
Near Infrared ◽  
Planet Formation ◽  
Accretion Rate ◽  
Initial Conditions ◽  
Early Evolution ◽  
Line Of Sight ◽  
Infrared Measurements ◽  
Bona Fide

AbstractThe early evolution of Sun-like stars may be interspersed by energetic FU Orionis (FUor) type accretion outbursts. We analysed eight years of photometric and spectroscopic variability of V582 Aur, a bona fide FUor, in outburst. While the accretion rate derived from near-infrared measurements was constant, radical brightness changes occurred due to dust clumps crossing the line of sight. The brightness minima resemble the variability patterns of the UXor phenomenon. Orbiting density enhancements or short-lived clumps moving in and out of the line-of-sight may explain these observations. Our message is that during FUor outbursts the inner disk is a dynamically active place, affecting the initial conditions for planet formation.

scholarly journals Special Session 7 Young Stars, Brown Dwarfs, and Protoplanetary Disks

2009 ◽  
Vol 5 (H15) ◽  
pp. 727-728
Author(s):  
Jane Gregorio-Hetem ◽  
Silvia Alencar
Keyword(s):  
Adaptive Optics ◽  
Planet Formation ◽  
Protoplanetary Disks ◽  
Brown Dwarfs ◽  
Young Stars ◽  
Special Session ◽  
Brown Dwarf ◽  
X Ray ◽  
Substellar Objects

In recent years our knowledge of star, brown dwarf and planet formation has progressed immensely due to new data in the IR domain (Spitzer telescope), new X-ray campaigns such as the Chandra Orion Ultradeep Project (COUP) and the X-ray Emission Survey of Taurus (XEST), with XMM-Newton, as well as adaptive optics results and synoptic studies of young stellar and substellar objects.

scholarly journals Chemical diversity of super-Earths as a consequence of formation

2020 ◽  
Vol 493 (4) ◽  
pp. 4910-4924 ◽  
Author(s):  
Jennifer Scora ◽  
Diana Valencia ◽  
Alessandro Morbidelli ◽  
Seth Jacobson
Keyword(s):  
Solar System ◽  
Planet Formation ◽  
Initial Conditions ◽  
Chemical Diversity ◽  
Planetary Formation ◽  
Iron Depletion ◽  
Giant Impacts

ABSTRACT Recent observations of rocky super-Earths have revealed an apparent wider distribution of Fe/Mg ratios, or core to mantle ratios, than the planets in our Solar system. This study aims to understand how much of the chemical diversity in the super-Earth population can arise from giant impacts during planetary formation. Planet formation simulations have only recently begun to treat collisions more realistically in an attempt to replicate the planets in our Solar system. We investigate planet formation more generally by simulating the formation of rocky super-Earths with varying initial conditions using a version of symba, a gravitational N-body code, that incorporates realistic collisions. We track the maximum plausible change in composition after each impact. The final planets span a range of Fe/Mg ratios similar to the Solar system planets, but do not completely match the distribution in super-Earth data. We only form a few planets with minor iron-depletion, suggesting other mechanisms are at work. The most iron-rich planets have a lower Fe/Mg ratio than Mercury, and are less enriched than planets such as Kepler-100b. This indicates that further work on our understanding of planet formation and further improvement of precision of mass and radius measurements are required to explain planets at the extremes of this Fe/Mg distribution.

scholarly journals Ice-gas interactions during planet formation

2015 ◽  
Vol 11 (A29A) ◽  
pp. 267-270
Author(s):  
Karin I. Öberg
Keyword(s):  
Planet Formation ◽  
Building Blocks ◽  
Central Star ◽  
Chemical Processes ◽  
Young Stars ◽  
The Past ◽  
Gas Interactions ◽  
Physical And Chemical ◽  
Formation Efficiency

AbstractPlanets form in disks around young stars. In these disks, condensation fronts or snowlines of water, CO2, CO and other abundant molecules regulate the outcome of planet formation. Snowline locations determine how the elemental and molecular compositions of the gaseous and solid building blocks of planets evolve with distance from the central star. Snowlines may also locally increase the planet formation efficiency. Observations of snowlines have only become possible in the past couple of years. This proceeding reviews these observations as well as the theory on the physical and chemical processes in disks that affect snowline locations.

scholarly journals Terrestrial planet formation in low-mass disks: dependence with initial conditions

2014 ◽  
Vol 9 (S310) ◽  
pp. 218-219
Author(s):  
M. P. Ronco ◽  
G. C. de Elía ◽  
O. M. Guilera
Keyword(s):  
Gas Phase ◽  
Analytical Model ◽  
Ad Hoc ◽  
Planet Formation ◽  
Initial Conditions ◽  
Planetary Systems ◽  
Terrestrial Planet ◽  
Initial Distribution ◽  
Protoplanetary Disk ◽  
Low Mass

AbstractIn general, most of the studies of terrestrial-type planet formation typically use ad hoc initial conditions. In this work we improved the initial conditions described in Ronco & de Elía (2014) starting with a semi-analytical model wich simulates the evolution of the protoplanetary disk during the gas phase. The results of the semi-analytical model are then used as initial conditions for the N-body simulations. We show that the planetary systems considered are not sensitive to the particular initial distribution of embryos and planetesimals and thus, the results are globally similar to those found in the previous work.

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