scholarly journals How does the mass and activity history of the host star affect the population of low-mass planets?

2021 ◽  
Vol 504 (2) ◽  
pp. 2034-2050
Author(s):  
Daria Kubyshkina ◽  
Aline A Vidotto
Keyword(s):  
Mass Star ◽  
Intermediate Mass ◽  
Solar Mass ◽  
Planetary Evolution ◽  
The Past ◽  
Strongly Connected ◽  
History Of ◽  
Low Mass ◽  
Host Stars ◽  
Atmospheric Mass

ABSTRACT The evolution of the atmospheres of low- and intermediate-mass planets is strongly connected to the physical properties of their host stars. The types and the past activities of planet-hosting stars can, therefore, affect the overall planetary population. In this paper, we perform a comparative study of sub-Neptune-like planets orbiting stars of different masses and different evolutionary histories. We discuss the general patterns of the evolved population as a function of parameters and environments of planets. As a model of the atmospheric evolution, we employ the own framework combining planetary evolution in Modules for Experiments in Stellar Astrophysics (mesa) with the realistic prescription of the escape of hydrogen-dominated atmospheres. We find that the final populations look qualitatively similar in terms of the atmospheres survival around different stars, but qualitatively different, with this difference accentuated for planets orbiting more massive stars. We show that a planet has larger chances of keeping its primordial atmosphere in the habitable zone of a solar-mass star compared to M or K dwarfs and if it starts the evolution having a relatively compact envelope. We also address the problem of the uncertain initial temperatures (luminosities) of planets and show that this issue is only of particular importance for planets exposed to extreme atmospheric mass losses.

scholarly journals How does the mass and activity history of the host star affect the population of low-mass planets?

2021 ◽  
Author(s):  
Daria Kubyshkina ◽  
Aline Vidotto
Keyword(s):  
Comparative Study ◽  
Massive Stars ◽  
Intermediate Mass ◽  
Planetary Evolution ◽  
Atmospheric Escape ◽  
The Past ◽  
Strongly Connected ◽  
History Of ◽  
Low Mass ◽  
Host Stars

<p>The evolution of the atmospheres of low and intermediate-mass planets is strongly connected to the physical properties of their host stars. The types and the past activities of planet-hosting stars can, therefore, affect the overall planetary population. We perform a comparative study of sub-Neptune-like planets orbiting stars of different masses and different evolutionary histories. As a model of atmospheric evolution, we employ our own framework combining planetary evolution in MESA with a realistic prescription of the escape of hydrogen-dominated atmospheres. We discuss general patterns of the evolved population as a function of planetary and stellar parameters. The final populations look qualitatively similar in terms of the atmospheres' survival around different stars, but quantitatively different, with this difference accentuated for planets orbiting more massive stars. We will discuss the potential input from different atmospheric escape mechanisms in shaping these populations.</p>

scholarly journals The high latitude low mass star forming region Cometary Globule 12: two compact cores and a C18O hot spot

2006 ◽  
Vol 2 (S237) ◽  
pp. 420-420
Author(s):  
L. K. Haikala ◽  
M. Juvela ◽  
J. Harju ◽  
K. Lehtinen ◽  
K. Mattila ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Hot Spot ◽  
Mass Star ◽  
Intermediate Mass ◽  
Solar Mass ◽  
Stellar Cluster ◽  
Star Forming ◽  
Continuum Source ◽  
Nir Imaging ◽  
Low Mass

AbstractCometary globule CG 12 lies at the distance of 630 pc more than 200 pc above the Galactic plane. The cloud's structure could be due to the passage of a supernova blast wave. Curiously, the cometary tail points at the galactic plane which would put the putative supernova even farther above the Galactic plane than the globule. The globule contains a low/intermediate mass stellar cluster with at least 9 members (Williams et al. 1977). The head of CG 12 has been observed using NIR imaging (NTT SOFI), mm continuum (SEST SIMBA) and sub mm (APEX) and mm (SEST) spectroscopy (Haikala & Olberg 2006, Haikala et al.). The molecular material is distributed in a North-South 10' long elongated lane with two compact maxima separated by 3'. Strong C18O (3-2), (2-1) and (1-0) emission is detected in both maxima and both have an associated compact 1.2 mm continuum source. The Northern core, CG 12 N, is cold and is possibly still pre-stellar. A dense and compact core is observed in DCO+ and CS emission in the direction of the Southern core, CG 12 S. A remarkable C18O hot spot was detected in CG 12 S. This is the first detection of such a compact, warm object in a low mass star forming region. The hot spot can be modelled with a 60″ to 80″ diameter (~0.2 pc) hot (80 K ≲ Tex≲ 100 K) 1.6 solar mass clump (Haikala et al. 2006). The hot spot lies at the edge of a dense cloud core and on the axis of a highly collimated bipolar molecular outflow (White 1993). The driving source of the outflow is most probably embedded in the dense core. NIR imaging reveals a bright cone like feature with a faint counter cone in the centre of CG 12 S. The size of the CG 12 compact head, 1.1 pc by 1.8 pc, and the C18O mass larger than 100 solar masses are comparable to those of other nearby low/intermediate mass star formation regions.

scholarly journals Warm gas in protostellar outflows

2019 ◽  
Vol 629 ◽  
pp. A77
Author(s):  
A. I. Gómez-Ruiz ◽  
A. Gusdorf ◽  
S. Leurini ◽  
K. M. Menten ◽  
S. Takahashi ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
High Velocity ◽  
The Other ◽  
Mass Star ◽  
Intermediate Mass ◽  
Star Forming ◽  
Physical Conditions ◽  
Star Forming Regions ◽  
Low Mass ◽  
Kinematic Properties

Context. OMC-2/3 is one of the nearest embedded cluster-forming regions that includes intermediate-mass protostars at early stages of evolution. A previous CO (3–2) mapping survey towards this region revealed outflow activity related to sources at different evolutionary phases. Aims. The present work presents a study of the warm gas in the high-velocity emission from several outflows found in CO (3–2) emission by previous observations, determines their physical conditions, and makes a comparison with previous results in low-mass star-forming regions. Methods. We used the CHAMP+ heterodyne array on the APEX telescope to map the CO (6–5) and CO (7–6) emission in the OMC-2 FIR 6 and OMC-3 MMS 1-6 regions, and to observe 13CO (6–5) at selected positions. We analyzed these data together with previous CO (3–2) observations. In addition, we mapped the SiO (5–4) emission in OMC-2 FIR 6. Results. The CO (6–5) emission was detected in most of the outflow lobes in the mapped regions, while the CO (7–6) was found mostly in the OMC-3 outflows. In the OMC-3 MMS 5 outflow, a previously undetected extremely high-velocity gas was found in CO (6–5). This extremely high-velocity emission arises from the regions close to the central object MMS 5. Radiative transfer models revealed that the high-velocity gas from MMS 5 outflow consists of gas with nH2 = 104–105 cm−3 and T > 200 K, similar to what is observed in young Class 0 low-mass protostars. For the other outflows, values of nH2 > 104 cm−3 were found. Conclusions. The physical conditions and kinematic properties of the young intermediate-mass outflows presented here are similar to those found in outflows from Class 0 low-mass objects. Due to their excitation requirements, mid − J CO lines are good tracers of extremely high-velocity gas in young outflows likely related to jets.

scholarly journals Exploring the formation by core accretion and the luminosity evolution of directly imaged planets

2019 ◽  
Vol 624 ◽  
pp. A20 ◽  
Author(s):  
Gabriel-Dominique Marleau ◽  
Gavin A. L. Coleman ◽  
Adrien Leleu ◽  
Christoph Mordasini
Keyword(s):  
Mass Star ◽  
Population Synthesis ◽  
Direct Imaging ◽  
Solar Mass ◽  
High Eccentricity ◽  
Body Dynamics ◽  
Low Mass ◽  
Open Question ◽  
Core Accretion ◽  
First Time

Context. A low-mass companion to the two-solar mass star HIP 65426 has recently been detected by SPHERE at around 100 au from its host. Explaining the presence of super-Jovian planets at large separations, as revealed by direct imaging, is currently an open question. Aims. We want to derive statistical constraints on the mass and initial entropy of HIP 65426 b and to explore possible formation pathways of directly imaged objects within the core-accretion paradigm, focusing on HIP 65426 b. Methods. Constraints on the planet’s mass and post-formation entropy are derived from its age and luminosity combined with cooling models. For the first time, the results of population synthesis are also used to inform the results. Then a formation model that includes N-body dynamics with several embryos per disc is used to study possible formation histories and the properties of possible additional companions. Finally, the outcomes of two- and three-planet scattering in the post-disc phase are analysed, taking tides into account for small-pericentre orbits. Results. The mass of HIP 65426 b is found to be mp = 9.9−1.8+1.1 MJ using the hot population and mp = 10.9−2.0+1.4 MJ with the cold-nominal population. We find that core formation at small separations from the star followed by outward scattering and runaway accretion at a few hundred astronomical units succeeds in reproducing the mass and separation of HIP 65426 b. Alternatively, systems having two or more giant planets close enough to be on an unstable orbit at disc dispersal are likely to end up with one planet on a wide HIP 65426 b-like orbit with a relatively high eccentricity (≳ 0.5). Conclusions. If this scattering scenario explains its formation, HIP 65426 b is predicted to have a high eccentricity and to be accompanied by one or several roughly Jovian-mass planets at smaller semi-major axes, which also could have a high eccentricity. This could be tested by further direct-imaging as well as radial-velocity observations.

The History of Low-Mass Star Formation in the Upper Scorpius OB Association

1999 ◽  
Vol 117 (5) ◽  
pp. 2381-2397 ◽  
Author(s):  
Thomas Preibisch ◽  
Hans Zinnecker
Keyword(s):  
Star Formation ◽  
Mass Star ◽  
History Of ◽  
Low Mass

scholarly journals Definitions, Summary, and Some Issues

2002 ◽  
Vol 12 ◽  
pp. 179-181
Author(s):  
Peter S. Conti
Keyword(s):  
Spectral Type ◽  
Massive Star ◽  
Massive Stars ◽  
Mass Star ◽  
Mass Limit ◽  
Physical Processes ◽  
Intermediate Mass ◽  
Observable Quantity ◽  
Low Mass ◽  
Final Evolution

This Joint Discussion has been titled Massive Star Birth. Perhaps it is appropriate here to define what we mean by a massive star. The very word massive suggests we consider aminimummassMbelow which one would speak of low (or intermediate) mass evolution, and above which is the realm of massive stars. It is natural to take this mass limit as that in which a (single) star will end its life as a supernova: 8M⊙. This corresponds to a (minimum) luminosityLof a few × 103L⊙, a (minimum)Teff of 20000 K, and a ZAMS spectral type of about B1.5V. Note that this mass division refers to the final evolution of a star, and might well have nothing to do with difference in physical processes between massive and low mass starbirth. For example, the minimumTeff for a star to produce an UCHII region, a readily observable quantity, corresponds to aTeffcloser to 30000 K and a mass of 15M⊙.

scholarly journals Infalling Streamer-Disk-Outflow System in a Nearby High-mass Star Formation Region

2021 ◽  
Author(s):  
Xi Chen ◽  
Zhiyuan Ren ◽  
Da-Lei Li ◽  
Tie Liu ◽  
Ke Wang ◽  
...  
Keyword(s):  
Direct Detection ◽  
Theoretical Models ◽  
Young Stellar Objects ◽  
High Mass ◽  
Similar Process ◽  
Mass Star ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Stellar Objects ◽  
Low Mass

Abstract Theoretical models and numerical simulations suggest that high mass star (with mass > 8 solar mass) can be formed either via monolithic collapse of a massive core or competitive accretion, but the dominant mechanism is currently unclear. Although recent high resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have detected physical and kinematic features, such as disks, outflows and filamentary structures surrounding the high mass young stellar objects (HMYSO), direct detection of the infalling gas towards the HMYSO is still the key to distinguish the different scenarios. Chemically fresh gas inflows have been detected towards low-mass stars being formed, which are consistent with the accretion-disk-outflow process. In this work we report the detection of a chemically fresh inflow which is feeding HMYSO growth in the nearby high mass star-forming region G352.63-1.07. High quality images of the dust and molecular lines from both ALMA and the Submillimeter Array (SMA) have consistently revealed a gravitationally-controlled gas inflow towards a rotating structure (disk or torus) around the HMYSO. The HMYSO is also observed to have an outflow, but it can be clearly separated from the inflow. These kinematic features provide observational evidence to support the conjecture that high-mass stars can be formed in a similar process to that observed in the low-mass counterparts. The chemically fresh infalling streamers could also be related with the disk configuration, fragmentation and accretion bursts that occur in both simulations and observations.

scholarly journals A centrally concentrated sub-solar-mass starless core in the Taurus L1495 filamentary complex

2019 ◽  
Vol 71 (4) ◽  
Author(s):  
Kazuki Tokuda ◽  
Kengo Tachihara ◽  
Kazuya Saigo ◽  
Phillipe André ◽  
Yosuke Miyamoto ◽  
...  
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
Volume Density ◽  
Mass Star ◽  
Brown Dwarf ◽  
Solar Mass ◽  
Star Forming ◽  
The Core ◽  
Order Of Magnitude ◽  
Low Mass

Abstract The formation scenario of brown dwarfs is still unclear because observational studies to investigate its initial condition are quite limited. Our systematic survey of nearby low-mass star-forming regions using the Atacama Compact Array (aka the Morita array) and the IRAM 30-m telescope in 1.2 mm continuum has identified a centrally concentrated starless condensation with a central H2 volume density of ∼106 cm−3, MC5-N, connected to a narrow (width ∼0.03 pc) filamentary cloud in the Taurus L1495 region. The mass of the core is $\sim {0.2\!-\!0.4}\, M_{\odot }$, which is an order of magnitude smaller than typical low-mass pre-stellar cores. Taking into account a typical core to star formation efficiency for pre-stellar cores (∼20%–40%) in nearby molecular clouds, brown dwarf(s) or very low-mass star(s) may be going to be formed in this core. We have found possible substructures at the high-density portion of the core, although much higher angular resolution observation is needed to clearly confirm them. The subsequent N2H+ and N2D+ observations using the Nobeyama 45-m telescope have confirmed the high-deuterium fractionation (∼30%). These dynamically and chemically evolved features indicate that this core is on the verge of proto-brown dwarf or very low-mass star formation and is an ideal source to investigate the initial conditions of such low-mass objects via gravitational collapse and/or fragmentation of the filamentary cloud complex.

scholarly journals Massive Star Formation: Observational Constraints

1997 ◽  
Vol 182 ◽  
pp. 525-536
Author(s):  
Ed Churchwell
Keyword(s):  
Star Formation ◽  
Accretion Disks ◽  
Massive Star ◽  
Young Stellar Objects ◽  
Mass Star ◽  
Structure And Properties ◽  
Low Mass Stars ◽  
Stellar Objects ◽  
The Past ◽  
Low Mass

Observations during the past several years strongly imply that virtually every star, independent of final mass, goes through a phase of rapid outflow simultaneously with rapid accretion during formation. The structure and properties of outflows and accretion disks associated with low-mass star formation has received intensive observational attention during the past several years (see the reviews and references in Lada 1985; Edwards, Ray, and Mundt 1993; Fukui et al. 1993; and this symposium). Young stellar objects (YSOs) with Lbol < 103 L⊘ will be referred to as “low-mass” stars in this review. The range of physical properties of CO outflows associated with YSOs of all masses are enormous, see Fukui et al. (1993). I will focus attention in this review on what we know about massive YSOs and their environments.

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