相关论文: The Pre--Main-Sequence of A-type stars
Young Sun-like stars at the beginning of the pre-main sequence (PMS) evolution are surrounded by accretion discs and remnant protostellar envelopes. Photometric and spectroscopic variations of these stars are driven by interactions of the…
The formation of a star is a dynamic process fed by the gravitational collapse of a molecular cloud core. Theoretical models and observations suggest that the majority of this infalling material settles into a protoplanetary disk before…
We argue that the first stars may have spanned the conventional mass range rather than be identified with the Very Massive Objects (100-1000 solar masses) favoured by numerical simulations. Specifically, we find that magnetic field…
Identifying the processes that determine strength, duration and variability of protostellar mass growth is a fundamental ingredient of any theory of star formation. I discuss protostellar mass accretion rates dM/dt from numerical models…
Intermediate mass Pre-main sequence stars (1.5 $M_{\odot}< M < 5M_{\odot}$) cross the instability strip on their way to the main sequence. They are therefore expected to be pulsating in a similar way as the $\delta$ Scuti stars. In this…
According to our understanding of stellar evolution, early-type stars have radiative envelopes and convective cores due to a steep temperature gradient produced by the CNO cycle. Some of these stars (mainly, the subclasses Ap and Bp) have…
The earliest phases of star formation are characterised by intense mass accretion from the circumstellar disk to the central star. One group of young stellar objects, the FU Orionis-type stars exhibit accretion rate peaks accompanied by…
Star formation often occurs within or nearby stellar clusters. Irradiation by nearby massive stars can photoevaporate protoplanetary disks around young stars (so-called proplyds) which raises questions regarding the ability of planet…
We present photometric ISO 60 and 170um measurements, complemented by some IRAS data at 60um, of a sample of 84 nearby main-sequence stars of spectral class A, F, G and K in order to determine the incidence of dust disks around such…
M-type stars are the most common stars in the universe. They are ideal hosts for the search of exoplanets in the habitable zone (HZ), as their small size and low temperature make the HZ much closer in than their solar twins. Harboring very…
Compared to planets around Sun-like stars, relatively little is known about the occurrence rate and orbital properties of planets around stars more massive than 1.3 Msun. The apparent deficit of planets around massive stars is due to a…
As the earliest stage of planet formation, massive, optically thick, and gas rich protoplanetary disks provide key insights into the physics of star and planet formation. When viewed edge-on, high resolution images offer a unique…
The bright maser emission produced by several molecular species at centimeter to long millimeter wavelengths provides an essential tool for understanding the process of massive star formation. Unimpeded by the high dust optical depths that…
We examine the consequences of radiatively driven warping of accretion disks surrounding pre-main-sequence stars. These disks are stable against warping if the luminosity arises from a steady accretion flow, but are unstable at late times…
The early evolution of protostellar, star-forming discs, including their density structure, turbulence, magnetic dynamics, and accretion variability, remains poorly understood. We present high-resolution magnetohydrodynamic simulations,…
The formation of planets with gaseous envelopes takes place in protoplanetary accretion discs on time-scales of several millions of years. Small dust particles stick to each other to form pebbles, pebbles concentrate in the turbulent flow…
The protoplanetary disks of Herbig Ae stars eventually dissipate leaving a tenuous debris disk comprised of planetesimals and dust, as well as possibly gas and planets. This paper uses the properties of 10-20Myr A star debris disks to…
The evidence of a relation between the mass accretion rate and the disk mass is established for young, Class II pre-main sequence stars. This observational result opened an avenue to test theoretical models and constrain the initial…
The details of the physical process through which high-mass stars form remains nearly as much of a mystery now as it was when the Parkes radio telescope commenced operation. The energy output from high-mass stars influence, or directly…
Almost all stars in the 1-8 Msun range evolve through the Asymptotic Giant Branch (AGB), preplanetary nebula (PPN) and planetary nebula (PN) evolutionary phases. Most stars that leave the main sequence in a Hubble time will end their lives…