Related papers: M17 MIR: A massive protostar with multiple accreti…
MHD models and the observation of accretion streamers confirmed that protostars can undergo late accretion events after the initial collapse phase. To provide better constraints, we study the evolution of stellar masses in MHD simulations…
Evidence abounds that young stellar objects undergo luminous bursts of intense accretion that are short compared to the time it takes to form a star. It remains unclear how much these events contribute to the main-sequence masses of the…
(Abriged) At present, there are two scenarios for the formation of massive stars: 1) The accretion scenario and 2) The coalescence scenario, which implies the merging of intermediate mass stars. We examine here some properties of the first…
We present the latest development of the disk gravitational instability and fragmentation model, originally introduced by us to explain episodic accretion bursts in the early stages of star formation. Using our numerical hydrodynamics model…
The twelfth accretion-powered millisecond pulsar, IGR J17511-3057, was discovered in September 2009. In this work we study its spectral and timing properties during the 2009 outburst based on Swift and RXTE data. Our spectral analysis of…
We present 29 likely members of the young $\rho$ Oph or Upper Sco regions of recent star formation that exhibit "accretion burst" type light curves in $K2$ time series photometry. The bursters were identified by visual examination of their…
The mid-infrared (MIR; $\lambda\simeq3 - 10\mu$m) bands offer a unique window into understanding accretion and its interplay with jet formation in Galactic black hole X-ray binaries (BHXRBs). Although extremely difficult to observe from the…
We report on the discovery of an FUor-like Class I protostar in NGC~7538. The source, named NGC~7538~MIR, exhibited a giant luminosity burst ($\Delta K_s\sim5$) and a prolonged high-luminosity state lasting at least five years. Its…
Young stellar objects (YSOs) may undergo periods of active accretion (outbursts), during which the protostellar accretion rate is temporarily enhanced by a few orders of magnitude. Whether or not these accretion outburst YSOs possess…
We present mid-infrared (MIR) observations, made with the TIMMI2 camera on the ESO 3.6 m telescope, toward 14 young massive star-forming regions. All regions were imaged in the N band, and nine in the Q band, with an angular resolution of ~…
Low-mass pre-main sequence (PMS) stars are strong X-ray sources, because they possess hot corona like their older main-sequence counterparts. Unique to young stars, however, are X-rays from accretion and outflows, and both processes are of…
We present coupled stellar evolution (SE) and 3D radiation-hydrodynamic (RHD) simulations of the evolution of primordial protostars, their immediate environment, and the dynamic accretion history under the influence of stellar ionizing and…
Protostars likely accrete material at a highly time variable rate, however, measurements of accretion variability from the youngest protostars are rare, as they are still deeply embedded within their envelopes. Sub-mm/mm observations can…
We present a multi-wavelength study of three star forming regions, spanning the age range 1-14 Myr, located between the 30 Doradus complex and supernova SN1987A in the Large Magellanic Cloud (LMC). We reliably identify about 1000 pre-main…
We study the formation and long-term evolution of primordial protostellar disks harbored by first stars using numerical hydrodynamics simulations in the thin-disk limit. The initial conditions are specified by pre-stellar cores with…
High-mass protostars (M$_{\star} >$ 8 M$_{\odot}$) are thought to gain the majority of their mass via short, intense bursts of growth. This episodic accretion is thought to be facilitated by gravitationally unstable and subsequently…
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…
Massive stars likely form by accretion and the evolutionary track of an accreting forming star corresponds to what is called the birthline in the HR diagram. The shape of this birthline is quite sensitive to the evolution of the entropy in…
At least half of a protostar's mass is accreted in the Class 0 phase, when the central protostar is deeply embedded in a dense, infalling envelope. We present the first systematic search for outbursts from Class 0 protostars in the Orion…
We have observed the cluster RX J0152.7-1357 (z$\sim$0.83) at 24$\mu$m with the Multiband Imaging Photometer for Spitzer (MIPS). We detected twenty-two sources associated with spectroscopically confirmed cluster members, while ten more have…