Related papers: The Relationship between Mid-Infrared and Sub-Mill…
We present the results of a J, H, and K photometric variability survey of the central 0.78 square degrees of the young OB association Cygnus OB2. We used data observed with the Wide-Field CAMera at the United Kingdom Infrared Telescope in…
We present new theoretical models for surface brightness fluctuations in the near-infrared. We show the time evolution of near-infrared brightness fluctuation properties over large age and metallicity ranges, i.e., from 12 Myr to 16 Gyr,…
Using newly released data from the Wide-field Infrared Survey Explorer, we report the discovery of rapid infrared variability in three radio-loud narrow-line Seyfert 1 galaxies (NLS1s) selected from the 23 sources in the sample of Yuan et…
We present molecular line observations made with the IRAM 30-m telescope of the immediate surroundings of a sample of 11 candidate high-mass protostars. These observations are part of an effort to clarify the evolutionary status of a set of…
Context. DG Tau is a low-mass pre-main sequence star, whose strongly accreting protoplanetary disk exhibits a so-far enigmatic behavior: its mid-infrared thermal emission is strongly time-variable, even turning the 10 $\mu$m silicate…
We present first results from a new, multiyear, time domain survey of young stars in the North America Nebula complex using the Palomar Transient Factory. Our survey is providing an unprecedented view of aperiodic variability in young stars…
We report the discovery of a mid-infrared outburst in a Young Stellar Object (YSO) with an amplitude close to 8 mag at $\lambda$$\approx$4.6 $\mu$m. WISEA J142238.82-611553.7 is one of 23 highly variable WISE sources discovered in a search…
We present multi-epoch Spitzer Space Telescope observations of the transitional disk LRLL 31 in the 2-3 Myr-old star forming region IC 348. Our measurements show remarkable mid-infrared variability on timescales as short as one week. The…
Massive young stellar objects are known to undergo an evolutionary phase in which high mass accretion rates drive strong outflows. A class of objects believed to trace this phase accurately is the GLIMPSE Extended Green Object (EGO) sample,…
Using the Spitzer and WISE images, we discovered 42 mid-IR luminous dusty supernovae with local integral-field spectroscopy data. The observed mid-IR emission indicates the presence of newly formed dust, or pre-existing dust heated by the…
The accretion histories of embedded protostars are an integral part of descriptions of their physical and chemical evolution. In particular, are the accretion rates smoothly declining from the earlier toward later stages or in fact…
Though there has been a significant amount of work investigating the early stages of low-mass star formation in recent years, the evolution of the mass assembly rate onto the central protostar remains largely unconstrained. Examining in…
We summarize results from flux density monitoring campaigns performed with the 100 meter radio-telescope at Effelsberg and the VLA during the past 15 yrs. We briefly discuss some of the statistical properties of the rapid variability from…
Identifying the population of young stellar objects (YSOs) in high extinction regions is a prerequisite for studies of star formation. This task is not trivial, as reddened background objects can be indistinguishable from YSOs in…
Accretion onto protostars may occur in sharp bursts. Accretion bursts during the embedded phase of young protostars are probably most intense, but can only be inferred indirectly through long-wavelength observations. We perform radiative…
The structure and properties of the diffuse interstellar medium (ISM) on small scales, sub-au to 1 pc, are poorly understood. We compare interstellar absorption-lines, observed towards a selection of O- and B-type stars at two or more…
UV/optical variability in quasars is a well-observed phenomenon, yet its primeval origins remain unclear. This study investigates whether the accretion disk turbulence, which is responsible for UV/optical variability, is influenced by the…
Long-baseline interferometry at infrared wavelengths allows the innermost regions around young stars to be observed. These observations directly probe the location of the dust and gas in the disks. The characteristic sizes of these regions…
We investigate the nature of the innermost regions of seven circumstellar disks around pre-main-sequence stars. Our object sample contains disks apparently at various stages of their evolution. Both single stars and spatially resolved…
Variable accretion in young stellar objects reveals itself photometrically and spectroscopically over a continuum of timescales and amplitudes. Most dramatic are the large outbursts (e.g., FU Ori, V1647 Ori, and EX Lup type events), but…