相关论文: Spectroscopy of 9 eruptive young variables using T…

The detection and characterization of accretion processes in the disks surrounding young stars may be directly relevant to studies of planet formation. Especially the study of systems with very low accretion rates (<< 10^{-10} M_sun…

We study the evolution of the normalized flux of selected ultraviolet emission lines of three classical novae (PW Vul, V1668 Cyg and V1974 Cyg). Different phases ofthe outbursts are studied. We attribute the spectral behavior of the three…

Extreme adaptive optics systems are now in operation across the globe. These systems, capable of high order wavefront correction, deliver Strehl ratios of 90% in the near-infrared. Originally intended for the direct imaging of exoplanets,…

In the episodic accretion scenario, a large fraction of the protostellar mass accretes during repeated and large bursts of accretion. Since outbursts on protostars are typically identified at specific wavelengths, interpreting these…

We report on the ongoing outburst of the young variable V1180 Cas, which is known to display characteristics in common with EXor eruptive variables. We present results that support the scenario of an accretion-driven nature of the…

We present an online catalog containing spectra and supporting information for cataclysmic variables that have been observed with the Far Ultraviolet Spectroscopic Explorer (FUSE). For each object in the catalog we list some of the basic…

FU Orionis-type objects (FUors) are low-mass pre-main-sequence objects which go through a short-lived phase (~100 years) of increased mass accretion rate (from 10^-8 to 10^-4 M_sun yr^-1). These eruptive young stars are in the early stages…

We present near-infrared spectra for a sample of T dwarfs, including eleven new discoveries made using the Two Micron All Sky Survey. These objects are distinguished from warmer (L-type) brown dwarfs by the presence of methane absorption…

We present high angular resolution observations with the Keck Interferometer, high dispersion spectroscopic observations with Keck/NIRSPEC, and near-IR photometric observations from PAIRITEL of a sample of 11 solar-type T Tauri stars in 9…

We present derived stellar and disc parameters for a sample of Taurus brown dwarfs both with and without evidence of an associated disc. These parameters have been derived using an online fitting tool (http://bd-server.astro.ex.ac.uk/),…

Optical and near-infrared variability is a well-known property of young stellar objects. However, a growing number of recent studies claim that a considerable fraction of them also exhibit mid-infrared flux changes. With the aim of studying…

The paper demonstrates the spectroscopic and photometric capabilities of the Ultra-Violet Imaging Telescope (UVIT) to study T-Tauri stars (TTSs). We present the first UVIT/Far-UV (FUV) spectrum of a TTS, TW Hya. Based on C~{\sc iv} line…

The near-star environment around young stars is very dynamic with winds, disks, and outflows. These processes are involved in star and planet formation, and influence the formation and habitability of planets around host stars. Even for the…

Context. The steep-spectrum radio quasars (SSRQs) are powerful radio sources, with thermal emission from accretion disk and jet nonthermal emission likely both contributing in the Ultraviolet (UV)/optical luminosity, however the former may…

Young associations in star forming regions are stellar systems that allow us to understand the mechanisms that characterise the stars in their early life and what happens around them. In particular, the analysis of the disks and of the…

We include gaseous continuum and line emission into our GALEV models for the spectral and photometric evolution of Simple Stellar Populations (SSPs) for various metallicities in the range 0.02 <= Z/Zsun <= 2.5. This allows to extend them to…

We reexamine the hypothesis that the optical/UV/soft X-ray continuum of Active Galactic Nuclei is thermal emission from an accretion disk. Previous studies have shown that fitting the spectra with the standard, optically thick and…

We present a study of accretion in a sample of 45 young, low mass objects in a variety of star forming regions and young associations, about half of which are likely substellar. Based primarily on the presence of broad, asymmetric Halpha…

We present high-spatial resolution HST and adaptive optics observations, and high-sensitivity ISO (ISOCAM & ISOPHOT) observations of a sample of X-ray selected weak-line (WTTS) and post (PTTS) T Tauri stars located in the nearby Chamaeleon…

We present high signal-to-noise, moderate spectral resolution (R ~ 2000-2500) near-infrared (0.8-5.0 micron) spectroscopy of the nearby T Tauri star TW Hya. By comparing the spectrum and the equivalent widths of several atomic and molecular…