Related papers: Haro 5-2: A New Pre-Main Sequence Quadruple Stella…

We report the discovery of a star-forming loop around the young, Crab-like supernova remnant (SNR) G54.1+0.3 using the AKARI infrared satellite. The loop consists of at least eleven young stellar objects (YSOs) embedded in a ring-like…

Using recent spectroscopic observations, we show that the triple system AO Vel with an eclipsing BpSi primary is in fact a remarkable quadruple system formed by two double-lined spectroscopic binaries with components close to the ZAMS. All…

Many classical Be stars acquire their very rapid rotation by mass and angular-momentum transfer in massive binaries. Short-lived intermediate-phase objects have only been discovered recently. Data archives and the literature have been…

Haro 2 is a blue compact dwarf galaxy and the closest (at 21Mpc) known $Ly\alpha$ emitter. UV and optical observations have found Haro 2 to be immersed in shells of partly ionized gas expanding at $\sim200$km/s. Observations of CO(2-1)…

We present HST/NICMOS observations with 0.1" (15 AU) resolution of six young stellar objects in the Taurus star-formation region. The targets of our survey are three Class I IRAS sources (IRAS 04016+2610, IRAS 04248+2612, and IRAS…

We report the detection of a wide young hierarchical triple system where the primary has a candidate debris disc. The primary, TYC 5241-986-1 A, is a known Tycho star which we classify as a late-K star with emission in the X-ray, near and…

We have carried out K-band speckle observations of a sample of 114 X-ray selected weak-line T Tauri stars in the nearby Scorpius-Centaurus OB association. We find that for binary T Tauri stars closely associated to the early type stars in…

AR Aur is a detached eclipsing binary containing two late-B stars which are chemically peculiar, on a circular orbit of period 4.135 d. The primary is a HgMn star which shows temporal changes in its chemical abundances and spectral line…

Orbital motions in four hierarchical stellar systems discovered by speckle interferometry are studied. Their inner orbits are relatively well constrained, while the long outer orbits are less certain. The eccentric and misaligned inner…

The B-emission line stars are rapid rotators that were probably spun up by mass and angular momentum accretion through mass transfer in an interacting binary. Mass transfer will strip the donor star of its envelope to create a small and hot…

We present multi-wavelength (VRIJHK) observations of KH 15D obtained in 2012/13, as well as a master table of standard photometry spanning the years 1967 to 2013. The system is a close, eccentric T Tauri binary embedded in an inclined…

We report sensitive Spitzer IRS spectroscopy in the 10-20 micron region of TW Hya, a nearby T Tauri star. The unusual spectral energy distribution of the source, that of a transition object, indicates that the circumstellar disk in the…

We studied a small comet-shape reflection nebula, located in the dark cloud SL 4 in the Vela Molecular Ridge cloud C, known as BBWo 192E (GM 1-23), and a young infrared cluster embedded into the nebula, for the evidences of recent star…

We have obtained 1.64, 1.90 and 2.15 micron narrow-band images of five T Tauri stars in the TW Hya Association (TWA) using the Near-Infrared Camera and Multiobject Spectrometer aboard the Hubble Space Telescope. Most of the T Tauri stars in…

The formation process of massive stars is still poorly understood. Massive young stellar objects (mYSOs) are deeply embedded in their parental clouds, they are rare and thus typically distant, and their reddened spectra usually preclude the…

Benchmark brown dwarfs in wide binary systems are crucial for characterizing substellar objects and calibrating atmospheric and evolutionary models. However, brown dwarf benchmarks with subsolar metallicity, very cool temperatures, or…

We present a detailed analysis of the extended structure detected around the young and close-by Herbig Ae/Be star RCrA. This is a young triple system with an intermediate mass central binary whose separation is of the order of a few tens of…

For three decades, adaptive optic surveys have revealed an excess of T Tauri binaries across a = 10-100 au in nearby star-forming regions compared to the field population of main-sequence (MS) stars. Such an excess requires that most stars…

Massive binary stars may constitute a substantial fraction of progenitors to supernovae and gamma-ray bursts, and the distribution of their orbital characteristics holds clues to the formation process of massive stars. As a contribution to…

We investigate the surroundings of the hypercompact HII region M17 UC1 to probe the physical properties of the associated young stellar objects and the environment of massive star formation. Five of the seven point sources in this region…