Related papers: Discovery of lambda Boo stars in open clusters
We perform a study of the spatial and kinematical distribution of young open clusters in the solar neighborhood, discerning between bound clusters and transient stellar condensations within our sample. Then, we discriminate between Gould…
I review the observational constraints on the star formation histories in the spheroids of M33 and M31, the other two spiral galaxies in the Local Group. M33 does not possess a traditional bulge; instead, it has a small nuclear region…
The recently-discovered lack of close binaries, among extreme horizontal branch (EHB) stars in Galactic globular clusters, has thus far constituted a major puzzle, in view of the fact that blue subdwarf stars - the field counterparts of…
We report the properties of a new young double stellar cluster in the region towards IRAS 07141-0920 contained in the HII region Sh2-294. High-resolution optical UBVRI and Halpha images, near-infrared JHKs and H2 filter images were used to…
This work studies the candidate double and multiple open clusters (OCs) in the galactic sector from l = 240o to l = 270o, which contains the Vela-Puppis star formation region. To do that, we have searched the most recent and complete…
Luminous blue variables (LBVs) are suprisingly isolated from the massive O-type stars that are their putative progenitors in single-star evolution, implicating LBVs as binary evolution products. Aadland et al. (A19) found that LBVs are,…
Our recent multi-band photometric study of the colour width of the lower main sequence of the open cluster M37 has revealed the presence of a sizeable initial chemical composition spread in the cluster. If initial chemical composition…
It is challenging to reliably identify stars that were born together outside of actively star-forming regions and bound stellar systems. However, co-natal stars should be present throughout the Galaxy, and their demographics can shed light…
Recent studies have identified star clusters with multiple components based on accurate spatial distributions and/or proper motions from Gaia DR3, utilising diverse diagnostics to improve our understanding of subgroup evolution. These…
It is currently widely accepted that open star clusters and stellar associations result from the evolution of embedded star clusters. Parameters such star formation efficiency, time-scale of gas removal and velocity dispersion can be…
Evidence for triggered star formation linking three generations of stars is difficult to assemble, as it requires convincingly associating evolved massive stars with Hii regions that, in turn, would need to present signs of active star…
Usually, a loose stellar distribution can be classified as an OB stellar group, an association, or a young open cluster. We make use of comparisons with the typical OB association Vul OB1. In the present paper we discuss the nature of…
We demonstrate that HD 174005, a star recently classified as belonging to the lambda Boo group, is in reality a double lined spectroscopic binary; at some phases, the observed composite spectrum may be similar to that of a single star with…
Open clusters are convenient probes of the structure and history of the Galactic disk. They are also fundamental to stellar evolution studies. The second Gaia data release contains precise astrometry at the sub-milliarcsecond level and…
A majority of massive stars are part of binary systems, a large fraction of which will inevitably interact during their lives. Binary-interaction products (BiPs), i.e. stars affected by such interaction, are expected to be commonly present…
Hot subdwarf stars (sdO/Bs) are evolved core helium-burning stars with very thin hydrogen envelopes, which can be formed by common envelope ejection. Close sdB binaries with massive white dwarf (WD) companions are potential progenitors of…
Open clusters belonging to star-forming complexes are the leftovers from the initial stellar generations. The study of these young systems provides constraints to models of star formation and evolution as well as to the properties of the…
We have investigated 1008 objects in the area of five intermediate age open clusters (NGC 2099, NGC 3114, NGC 6204, NGC 6705 and NGC 6756) via the narrow band Delta a-system. The detection limit for photometric peculiarity is very low…
We present results of a BVI variability survey in the young open cluster NGC 457 based on observations obtained during three separate runs spanning almost 20 years. In total, we found 79 variable stars, of which 66 are new. The BVI…
Observations suggest that there is a significant fraction of O-stars in the field of the Milky Way that appear to have formed in isolation or in low mass clusters ($<$100 $M_\odot$). The existence of these high-mass stars that apparently…