Related papers: Possible Time Correlation Between Jet Ejection and…
While the rate of accretion onto T Tauri stars is predicted to decline with age, objects with strong accretion have been detected up to ages of 10 Myr. We analyze a sample of these old accretors identified by having a significant $U$ band…
We analyze optical images and high-resolution, long-slit spectra of three planetary nebulae which possess collimated, low-ionization features. NGC 3918 is composed of an inner, spindle-shaped shell mildly inclined with respect to the plane…
We have simultaneously monitored the photometric and polarimetric variations of the Classical T Tauri star AA Tau during the fall of 2002. We combine these data with previously published polarimetric data covering two earlier epochs. The…
Accretion and ejection sets the outcome of the star and planet formation process. The mid-infrared wavelength range offers key tracers of those processes that were difficult to detect and spatially resolve in protostars until now. We aim to…
Young stars are known to show variability due to non-steady mass accretion rate from their circumstellar disks. Accretion flares can produce strong energetic irradiation and heating that may affect the disk in the planet formation region,…
DG Tau A, a class-II young stellar object (YSO) displays both thermal, and non-thermal, radio emission associated with its bipolar jet. To investigate the nature of this emission, we present sensitive ($\sigma\sim2\,\mu {\rm Jy…
We investigate the relation between the two modes of outflow (wind and jet) in radio-loud active galactic nuclei (AGN). For this study we have carried out a systematic and homogeneous analysis of XMM-Newton spectra of a sample of 16…
We present two epochs of observations of TW Hya from the high-dispersion near-IR spectrograph ARIES at the MMT. We detect strong emission from the Brackett gamma transition of hydrogen, indicating an accretion rate substantially larger than…
We present high angular resolution X-ray images and spectra from two {\em Chandra} ACIS-I observations of the X-ray jet in the nearby radio galaxy Centaurus A. We find that the X-ray emission from the jet is composed of a low surface…
We present a multi-epoch (20 years baseline) kinematical investigation of HH52, 53, and 54 at optical and near-IR wavelengths, along with medium and high- resolution spectroscopic analyses, probing the kinematical and physical time…
Context. In multiple pre-main-sequence systems the lifetime of circumstellar disks appears to be shorter than around single stars, and the actual dissipation process may depend on the binary parameters of the systems. Aims. We report high…
Long-term homogeneous photometry for 35 classical T Tauri stars (cTTS) in the Taurus-Auriga star-forming region (Tau-Aur SFR) has been analyzed. Reliable effective temperatures, interstellar extinctions, luminosities, radii, masses, and…
We use new and archival Chandra and ROSAT data to study the time variability of the X-ray emission from the pulsar wind nebula (PWN) powered by PSR B1509-58 on timescales of one week to twelve years. There is variability in the size,…
We present photometric and spectroscopic models of the Classical T Tauri star AA Tau. Photometric and spectroscopic variability present in observations of AA Tau is attributed to a magnetically induced warp in the accretion disc,…
We report on the X-ray spectral and spatial evolution of the Symbiotic star R Aqr. Through a multi-epoch observational campaign performed with Chandra between 2017 and 2022, we study the X-ray emission of this binary system, composed of an…
We present the statistical analysis of 33 flare-related coronal jets, and discuss the link between the jet and the flare properties in these events. We selected jets that were observed between 2010 and 2016 by the Atmospheric Imaging…
We examine the long-term spectroscopic and photometric variability of EX~Lupi and TW~Hya, studying the presence of stable accretion and the role it plays in the observed variability. Analysing the velocity modulations of the emission lines…
We present the detection of day-timescale periodic variability in the r-band lightcurve of newly outbursting FU Orionis-type object HBC 722, taken from > 42 nights of observation with the CQUEAN instrument on the McDonald Observatory 2.1m…
Equivalent widths and line widths of Ca II infrared triplet emission lines were measured in high-resolution optical spectra of 39 young stellar objects.We found that the equivalent widths of the emission lines decrease with stellar…
We aim to characterize the magnetospheric accretion process in the young stellar object V807 Tau, one of the most stable dippers revealed by K2 in the Taurus star forming region. We performed photometric and spectropolarimetric follow-up…