Related papers: An unusual very low-mass high-amplitude pre-main s…

Observations indicate that in young stellar clusters the binary fraction for massive stars is higher than for solar mass stars. For the Orion Nebula Cluster (ONC) there is a binary frequency of ~ 50% for solar-mass stars compared to 70-100%…

We present the results of our analysis on V1481 Ori (JW 239), a young SB2 in the Orion Nebula Cluster with a circumbinary disc accreting on the lower-mass component. The analysis is based on high-resolution spectroscopic data and…

Observed changes in protostellar brightness can be complicated to interpret. In our JCMT~Transient monitoring survey, we discovered that a young binary protostar, HOPS 373, is undergoing a modest $30\%$ brightness increase at 850 $\mu$m,…

We present the analysis of four 3.6 cm radio continuum archival observations of Orion obtained using the Very Large Array in its A-configuration, with $0\rlap.{''}3$ angular resolution. The observations were made during the period…

We report on a short optical monitoring programme of the narrow-line Seyfert 1 Galaxy IRAS 13224-3809. Previous X-ray observations of this object have shown persistent giant variability. The degree of variability at other wavelengths may…

According to most literature sources, the amplitude of the pulsational variability observed in gamma Doradus stars does not exceed 0.1 mag in Johnson V. We have analyzed fifteen high-amplitude gamma Doradus stars with photometric…

Optical monitoring of S5 0716+714 was performed with a 60/90 Schmidt telescope in 2003 November and December and 2004 January for studying the variability of the object on short timescales. Due to the high brightness of the source we could…

Chemically peculiar stars of the upper part of the main sequence show periodical variability in line intensities and continua, modulated by the stellar rotation, which is attributed to the existence of chemical spots on the surface of these…

X-rays from massive stars are ubiquitous yet not clearly understood. In an XMM-Newton observation devoted to observe the first site of star formation in the $\rho$ Ophiuchi dark cloud, we detect smoothly variable X-ray emission from the…

Aims. We report the discovery of periodic maser variability of an unusual pattern in the high-mass young stellar object G26.598-0.024. Methods. A ten-year monitoring of the 6.7 GHz methanol maser was carried out with the Torun 32 m radio…

New multi-epoch, mid-infrared (8-13 microns) spectrophotometric observations are presented for 30~late-type stars. The observations were collected over a four year period (1994-1997), permitting an investigation of the mid-infrared spectral…

A fraction of the extreme horizontal branch stars of globular clusters exhibit a periodic light variability that has been attributed to rotational modulation caused by surface spots. These spots are believed to be connected to inhomogeneous…

Echelle spectrophotometry of the planetary nebula NGC 5307 is presented. The data consists of VLT UVES observations in the 3100 to 10360 A range. Electron temperatures and densities have been determined using different line intensity…

Using multi-epoch VLA observations, covering a time baseline of 29.1 years, we have measured the proper motions of 88 young stars with compact radio emission in the core of the Orion Nebula Cluster (ONC) and the neighboring BN/KL region.…

We report on the detection of a molecular band centered at ~98 um (~102 cm^-1), observed with the Infrared Space Observatory in the young Planetary Nebula NGC7027. The band structure and intensity can not be reproduced by atomic fine…

We report observations of three rotational transitions of molecular oxygen (O2) in emission from the H2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using HIFI on…

We present the results of a long-term monitoring campaign of the H\alpha line in a sample of bright OB-supergiants (O7.5-B9) that aims at detecting rotationally modulated changes potentially related to the existence of large-scale wind…

We present Spitzer Space Telescope observations of 11 regions SE of the Bright Bar in the Orion Nebula, along a radial from the exciting star theta1OriC, extending from 2.6 to 12.1'. Our Cycle 5 programme obtained deep spectra with matching…

Periodic increases in luminosity arising from variable accretion rates have been predicted for some close pre-main sequence binary stars as they grow from circumbinary disks. The phenomenon is known as "pulsed accretion" and can affect the…

Variability in the brightness of Young Stellar Objects (YSOs) is a common phenomenon that can be caused by changes in various factors, including accretion, extinction, disk morphology, interactions between the disk and the stellar…