Search Publications
Abundances of the light elements from UV (HST) and red (ESO) spectra in the very old star HD 84937
Spite, M.; Barbuy, B.; Spite, F. +2 more
Aims: In order to provide a better basis for the study of mechanisms of nucleosynthesis of the light elements beyond hydrogen and helium in the oldest stars, the abundances of C, O, Mg, Si, P, S, K, and Ca have been derived from UV-HST and visible-ESO high resolution spectra in the old, very metal-poor star HD 84937, at a metallicity that is …
The protoplanetary system HD 100546 in Hα polarized light from SPHERE/ZIMPOL. A bar-like structure across the disk gap?
Lumsden, S. L.; Mendigutía, I.; Huélamo, N. +7 more
Context. HD 100546 is one of the few known pre-main-sequence stars that may host a planetary system in its disk.
Aims: This work aims to contribute to our understanding of HD 100546 by analyzing new polarimetric images with high spatial resolution.
Methods: Using VLT/SPHERE/ZIMPOL with two filters in Hα and the adjacent continuum, we hav…
A comprehensive study of young B stars in NGC 2264 . I. Space photometry and asteroseismology
Fossati, L.; Przybilla, N.; Nieva, M. -F. +9 more
Context. Space photometric time series of the most massive members of the young open cluster NGC 2264 allow us to study their different sources of variability down to the millimagnitude level and permit a search for slowly pulsating B (SPB)-type pulsation among objects that are only a few million years old.
Aims: Our goal is to conduct a homo…
The transitional millisecond pulsar IGR J18245-2452 during its 2013 outburst at X-rays and soft gamma-rays
Stella, L.; Ferrigno, C.; Bozzo, E. +4 more
IGR J18245-2452/PSR J1824-2452I is one of the rare transitional accreting millisecond X-ray pulsars, showing direct evidence of switches between states of rotation-powered radio pulsations and accretion-powered X-ray pulsations, dubbed transitional pulsars. IGR J18245-2452 with a spin frequency of 254.3 Hz is the only transitional pulsar so far to…
The massive multiple system HD 64315
Montes, D.; Simón-Díaz, S.; Evans, C. J. +4 more
Context. The O6 Vn star HD 64315 is believed to belong to the star-forming region known as NGC 2467, but previous distance estimates do not support this association. Moreover, it has been identified as a spectroscopic binary, but existing data support contradictory values for its orbital period.
Aims: We explore the multiple nature of this st…
π Aquarii is another γ Cassiopeiae object
Nazé, Yaël; Rauw, Gregor; Cazorla, Constantin
The γ Cas category is a subgroup of Be stars displaying a strong, hard, and variable thermal X-ray emission. An XMM-Newton observation of π Aqr reveals spectral and temporal characteristics that clearly make this Be star another member of the γ Cas category. Furthermore, π Aqr is a binary but, contrary to γ Cas, the nature of the companion to the …
Spectroscopic and photometric oscillatory envelope variability during the S Doradus outburst of the luminous blue variable R71
Stahl, O.; Asmus, D.; Bartlett, E. S. +7 more
Context. Luminous blue variables (LBVs) are evolved massive stars that exhibit instabilities that are not yet understood. Stars can lose several solar masses during this evolutionary phase. The LBV phenomenon is thus critical to our understanding of the evolution of the most massive stars.
Aims: The LBV R71 in the Large Magellanic Cloud is pr…
The VLT-FLAMES Tarantula Survey. XXVII. Physical parameters of B-type main-sequence binary systems in the Tarantula nebula
Howarth, I. D.; Crowther, P. A.; Dufton, P. L. +14 more
A spectroscopic analysis has been undertaken for the B-type multiple systems (excluding those with supergiant primaries) in the VLT-FLAMES Tarantula Survey (VFTS). Projected rotational velocities, vesini, for the primaries have been estimated using a Fourier Transform technique and confirmed by fitting rotationally broadened profiles. A…
Multiple kinematical populations in Vela OB2 from Gaia DR1 data
Randich, S.; Micela, G.; Jeffries, R. D. +3 more
Context. Recent results using radial-velocity measurements from the Gaia-ESO Survey have led to the discovery of multiple kinematic populations across the Vela OB2 association. We present here a proper-motion study of the same region.
Aims: Our aim is to test whether or not the radial-velocity populations have a counterpart in proper-motion s…
Uncrowding R 136 from VLT/SPHERE extreme adaptive optics
Avenhaus, H.; Robbe-Dubois, S.; Vakili, F. +12 more
This paper presents the sharpest near-IR images of the massive cluster R 136 to date, based on the extreme adaptive optics of the SPHERE focal instrument implemented on the ESO Very Large Telescope and operated in its IRDIS imaging mode.The crowded stellar population in the core of the R 136 starburst compact cluster remains still to be characteri…