Related papers: An episodically variable stellar wind in the plane…
Massive stars show a variety of spectral variability: presence of discrete absorption components in UV P-Cygni profiles, optical line profile variability, X-ray variability, radial velocity modulations. Our goal is to study the spectral…
We report on high-resolution optical time-series spectroscopy of the central star of the `Eskimo' planetary nebula NGC~2392. Datasets were secured with the ESO 2.3m in 2006 March and CFHT 3.6m in 2010 March to diagnose the fast wind and…
To diagnose the time-variable structure in the fast winds of central stars of planetary nebulae (CSPN), we present an analysis of P Cygni line profiles in FUSE satellite far-UV spectroscopic data. Archival spectra are retrieved to form…
Spectrophotometric data of the young planetary nebula M 3-27, from 2004 to 2021, are presented and discussed. We corroborate that the H I Balmer lines present features indicating they are emitted by the central star, therefore He I lines…
The magnetic field in the O9.7 V star HD54879 has been monitored for almost a decade. Spectropolarimetric observations reveal a rather strong mean longitudinal magnetic field that varies with a period of about 7.41 yr. Observations in the…
We present three years of long-cadence and over one year of short-cadence photometry of the central star of the Planetary Nebula NGC 6826 obtained with the Kepler spacecraft, and temporally coinciding optical spectroscopy. The light curves…
We present the results of high-resolution spectroscopy of the extremely luminous star CygOB2-No.12. We identified about 200 spectral features in the range 4552-7939 AA, including the interstellar NaI, KI lines and numerous very strong DIBs,…
IRAS 22568+6141 has been classified as a low-ionisation planetary nebula (PN) and presents non-thermal radio continuum emission, which could be a signature of nascent PNe. We present intermediate-resolution long-slit spectra obtained in…
We investigate the line-profile variability (lpv) of H-alpha for a large sample of O-type supergiants. We used the Temporal Variance Spectrum (TVS) analysis, developed by Fullerton et al 1996 and modified by us to take into account the…
We present ALMA and ATCA observations of the luminous blue variable \rmc. The radio maps show for the first time the core of the nebula and evidence that the nebula is strongly asymmetric with a Z-pattern shape. Hints of this morphology are…
Spectral monitoring of the yellow hypergiant $\rho$ Cas with the by 6-m telescope of the Special Astrophysical Observatory with a spectral resolution of R$\ge$60000 has led to the detection of new features in the kinematic state of its…
High-resolution optical spectra of the B[e] star CI Cam were obtained on arbitrary dates 2002-2023 using the echelle spectrograph NES of the 6-m BTA telescope. The temporal variability of the powerful emissions of H$\alpha$ and HeI profiles…
Observation of Interplanetary Scintillation (IPS) provides an important and effective way to study the solar wind and the space weather. A series of IPS observations were conducted by the Five-hundred-meter Aperture Spherical radio…
The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM\,1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the…
The transition from early Of stars to WN type objects is poorly understood. O-type supergiants with emission lines (OIf+) are considered to be intermediate between these two classes. The scope of this paper is to investigate the spectral…
In this paper we explore the dynamics of ionization bounded planetary nebulae after the termination of the fast stellar wind. When the stellar wind becomes negligible, the hot, shocked bubble depressurizes and the thermal pressure of the…
We present photoelectric and spectral observations of a hot candidate proto-planetary nebula - early B-type supergiant with emission lines in spectrum - IRAS 19336-0400. The light and color curves display fast irregular brightness…
Cyclical wind variability is an ubiquitous but as yet unexplained feature among OB stars. The O7.5 III(n)((f)) star xi Persei is the brightest representative of this class on the Northern hemisphere. As its prominent cyclical wind…
Observations of nearby molecular clouds detect "shells", which are likely caused by winds from young main sequence stars. However, the progenitors of these observed features are not well characterized and the mass-loss rates inferred from…
We report the discovery of an extended halo (40' in diameter) around the planetary nebula NGC7293 (the Helix Nebula) observed in 12micron band from the Wide-field Infrared Survey Explorer all-sky survey. The mid-infrared halo has an…