Related papers: Herbig Ae/Be stars towards the dark cloud LDN 1667

Be stars, which are characterised by intermittent emission in their hydrogen lines, are known to be fast rotators. This fast rotation is a requirement for the formation of a Keplerian disk, which in turn gives rise to the emission. However,…

We have observed the protoplanetary disk of the well-known young Herbig star HD 142527 using ZIMPOL Polarimetric Differential Imaging with the VBB (Very Broad Band, ~600-900nm) filter. We obtained two datasets in May 2015 and March 2016.…

We present spectroscopic observations of diffuse ionized gas (DIG) in M33 near the HII region NGC 604. We present the first detection of [OI] 6300 in the DIG of M33, one of the critical lines for distinguishing photo- from shock ionization…

Most $\gamma$-ray detected active galactic nuclei are blazars with one of their relativistic jets pointing towards the Earth. Only a few objects belong to the class of radio galaxies or misaligned blazars. Here, we investigate the nature of…

Nitrogen is produced by CNO-cycling in massive stars, and can be ejected in significant amounts in supernova explosions. While in H-rich SNe, its [\ion{N}{II}] 6548, 6583 emission becomes obscured by strong H$\alpha$, in explosions of He…

The optical surface brightness of dark nebulae is mainly due to scattering of integrated starlight by classical dust grains. It contains information on the impinging interstellar radiation field, cloud structure, and grain scattering…

Observations of the supernova remnant G22.7-0.2 in the field of view of W41 with the H.E.S.S. telescope array have resulted in evidence for a very high energy (VHE) gamma-ray emission from the direction of the object. The emission region is…

A deep objective-prism survey for H-alpha emission stars towards the Canis Major star-forming clouds was performed. A total of 398 Halpha emitters were detected, 353 of which are new detections. There is a strong concentration of these…

We present new high and low resolution spectroscopic and photometric data of nine members of the young association CMa R1. All the stars have circumstellar dust at some distance as could be expected from their association with reflection…

As part of a mid-infrared spectroscopic survey of young stars with the Spitzer Space Telescope, an unclassified red emission line object was discovered. Based on its high ionization state indicated by the Spitzer spectrum, this object could…

Young early-type HAeBe stars are still embedded in the molecular clouds in which they formed. They illuminate reflection nebulae, which shape the surrounding molecular cloud and may trigger star formation. They are therefore ideal places to…

The residuals of the distance moduli of Type Ia supernovae (SN Ia) relative to a Hubble diagram fit contain information about the inhomogeneity of the universe, due to weak lensing magnification by foreground matter. By correlating the…

One of the strongest absorption lines observed in far-ultraviolet FUSE spectra of many PG1159 stars remained unidentified up to now. We show that this line, located at 973.3A, stems from NeVII. We also present new optical high-resolution…

Using ~1,700,000 target- and sky-fiber spectra from the SDSS, we have carried out a systematic search for Galactic planetary nebulae (PNe) via detections of the [OIII] 4959, 5007 lines. Thanks to the excellent sensitivity of the SDSS…

We present the results of optical and near-IR spectroscopic and near-IR photometric observations of the emission-line stars Hen3-298 and Hen3-303. Strong emission in the H-alpha line is found in both objects. The presence of Fe II and [O I]…

Spectroscopic observations of 48 emission-line objects of M33 have been obtained with the multi-object, wide field, fibre spectrograph AF2/WYFFOS at the 4.2m WHT telescope (La Palma, Spain). Line intensities and logarithmic extinction,…

In this series of papers we have presented the results of a spectroscopic survey of luminous and variable stars in the nearby spirals M31 and M33. In this paper, we present spectroscopy of 132 additional luminous stars, variables, and…

We report the first detection of asymmetry in a supernova (SN) photosphere based on SN light echo (LE) spectra of Cas A from the different perspectives of dust concentrations on its LE ellipsoid. New LEs are reported based on difference…

We selected 4593 hot subdwarf candidates from the Gaia DR2 Hertzsprung-Russell (HR) diagram. By combining the sample with LAMOST DR5, we identified 294 hot subdwarf stars, including 169 sdB, 63 sdOB, 31 He-sdOB, 22 sdO, 7 He-sdO and 2…

There is a wide consensus that type Ia supernovae (SN Ia) originate from the thermonuclear explosion of CO white dwarfs (WD), with the lack of hydrogen in the observed spectra as a distinctive feature. Here, we present SN 2016jae, which was…