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Protostellar outflows and jets are almost ubiquitous characteristics during the mass accretion phase, and encode the history of stellar accretion, complex-organic molecule (COM) formation, and planet formation. Episodic jets are likely…

Outbursts due to dramatic increases in the mass accretion rate are the most extreme type of variability in young stellar objects. We searched for outbursts among 319 protostars in the Orion molecular clouds by comparing 3.6, 4.5, and 24…

Solar and Stellar Astrophysics · Physics 2019-03-06 William J. Fischer , Emily Safron , S. Thomas Megeath

A star acquires much of its mass by accreting material from a disc. Accretion is probably not continuous but episodic. We have developed a method to include the effects of episodic accretion in simulations of star formation. Episodic…

Astrophysics of Galaxies · Physics 2015-05-27 Dimitris Stamatellos , Anthony Whitworth , David Hubber

This paper describes eruptive phenomena in pre-main sequence stars. The eruptions of FU Orionis stars have much in common with outbursts in other accreting systems, such as dwarf novae and some symbiotic stars. These common features are…

Astrophysics · Physics 2007-05-23 Scott J. Kenyon

The loss of mass from protostars, in the form of a jet or outflow, is a necessary counterpart to protostellar mass accretion. Outflow ejection events probably vary in their velocity and/or in the rate of mass loss. Such `episodic' ejection…

Stars collect most of their mass during the protostellar stage, yet the accretion luminosity and stellar parameters, which are needed to compute the mass accretion rate, are poorly constrained for the youngest sources. The aim of this work…

We study the evaporation and condensation of CO and CO_2 during the embedded stages of low-mass star formation by using numerical simulations. We focus on the effect of luminosity bursts, similar in magnitude to FUors and EXors, on the…

Solar and Stellar Astrophysics · Physics 2015-06-16 Eduard I. Vorobyov , I. Baraffe , T. Harries , G. Chabrier

The surroundings of massive protostars constitute an accretion disc which has numerically been shown to be subject to fragmentation and responsible for luminous accretion-driven outbursts. Moreover, it is suspected to produce close binary…

Solar and Stellar Astrophysics · Physics 2017-12-06 D. M. -A. Meyer , R. Kuiper , W. Kley , K. G. Johnston , E. Vorobyov

High-mass young stellar objects (HMYSOs) can exhibit episodic bursts of accretion, accompanied by intense outflows and luminosity variations. Thermal Instability (TI) due to Hydrogen ionisation is among the most promising mechanisms of…

Solar and Stellar Astrophysics · Physics 2024-12-18 Vardan G. Elbakyan , Sergei Nayakshin , Alessio Caratti o Garatti , Rolf Kuiper , Zhen Guo

We present results from a coordinated, multi-epoch near-infrared and centimeter radio survey of young stellar objects (YSOs) in the Coronet, aimed at probing the connection between mass accretion and ionised mass loss. Using VLT-KMOS, we…

Motivated by the recent detection of a large number of embedded young stellar objects (YSOs) with mass accretion rates that are inconsistent with the predictions of the standard model of inside-out collapse (Shu 1977), we perform a series…

Solar and Stellar Astrophysics · Physics 2015-05-14 E. I. Vorobyov

The mass accretion process controls pre-main-sequence evolution, although its intrinsic instability has yet to be fully understood, especially towards the protostellar stage. In this work, we have undertaken a thorough examination of the…

Solar and Stellar Astrophysics · Physics 2025-01-08 C. Morris , Z. Guo , P. W. Lucas , N. Miller , C. Contreras Peña , M. A. Kuhn

We present numerical simulations of circumbinary accretion onto eccentric and circular binaries using the moving-mesh code AREPO. This is the first set of simulations to tackle the problem of binary accretion using a finite-volume scheme on…

Earth and Planetary Astrophysics · Physics 2016-08-17 Diego J. Muñoz , Dong Lai

Accretion rates of order 10^-8 M_\odot/yr are observed in young protostars of approximately a solar mass with evidence of circumstellar disks. The accretion rate is significantly lower for protostars of smaller mass, approximately…

Astrophysics · Physics 2009-11-10 Paolo Padoan , Alexei Kritsuk , Michael L. Norman , Ake Nordlund

In this article, we proceed to study convection as a possible factor of episodic accretion in protoplanetary disks. Within the model presented in Article~I, the accretion history is analyzed at different rates and areas of matter inflow…

Solar and Stellar Astrophysics · Physics 2020-09-17 L. A. Maksimova , Ya. N. Pavlyuchenkov , A. V. Tutukov

A model of core-clump accretion with equally likely stopping describes star formation in the dense parts of clusters, where models of isolated collapsing cores may not apply. Each core accretes at a constant rate onto its protostar, while…

Astrophysics of Galaxies · Physics 2015-05-30 Philip C. Myers

Solar-mass stars form via circumstellar disk accretion (disk-mediated accretion). Recent findings indicate that this process is likely episodic in the form of accretion bursts, possibly caused by disk fragmentation. Although it cannot be…

The formation and evolution of a circumstellar disk in magnetized cloud cores is investigated from prestellar core stage until sim 10^4 yr after protostar formation. In the circumstellar disk, fragmentation first occurs due to gravitational…

Solar and Stellar Astrophysics · Physics 2015-05-27 Masahiro N. Machida , Shu-ichiro Inutsuka , Tomoaki Matsumoto

The idea that non steady accretion during the embedded phase of protostar evolution can produce the observed luminosity spread in the Herzsprung-Russell diagram (HRD) of young clusters has recently been called into question. Observations of…

Solar and Stellar Astrophysics · Physics 2015-06-05 Isabelle Baraffe , Eduard Vorobyov , Gilles Chabrier

The standard picture of accretion is a steady flow of matter from the disc onto the young star - a concept which assumes the star-disc system to be completely isolated. However, in a dense cluster environment star-disc systems do interact…

Astrophysics · Physics 2015-05-13 S. Pfalzner , J. Tackenberg , M. Steinhausen