A photometric study of the Orion OB 1 association. III - Subgroup analyses

Warren, W. H.; Hesser, J. E.

doi:10.1086/190510

Cited by 118 publications

(105 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Identified as a photometric nonmember in the Ori OB 1b association subgroup in the early work of Warren & Hesser (1978), the measurement of a high lithium abundance in HD 294297 by Cunha et al (1995), log (Li) NLTE = 2.56, was in contrast used as an evidence of its youth. Furthermore, the star was one of the only two "young solar-type members of the Orion association" that were observed with STIS onboard the Hubble Space Telescope to investigate their boron abundance (Cunha et al 2000).…”

Section: Hd 294297mentioning

confidence: 99%

Stars and brown dwarfs in theσ Orionis cluster

Caballero¹

2010

A&A

View full text Add to dashboard Cite

Aims. I attempt to fully understand the origin of the stellar and substellar populations in the young σ Orionis open cluster, which is a benchmark for star-forming studies. Because of the very low proper motion of the cluster, late-type dwarfs with appreciable proper motion in the foreground of σ Orionis can be easily discarded as targets from expensive spectroscopic follow-up studies. Methods. I use the Aladin sky atlas, USNO-B1, public astrometric catalogues, and photographic plate digitisations to identify stars with proper motions that are inconsistent with cluster membership in a circular area of radius 30 arcmin centred on the early-type multiple system σ Ori. Primarily because of the long time baseline of more than half a century, the errors in the measured proper motions are lower than 2 mas a −1 . Results. Of the 42 stars selected for astrometric follow-up, 37 of them are proper-motion cluster interlopers. Some USNO-B1 measurements were affected by partially resolved (visual) multiplicity and target faintness. Because of their late spectral types and, hence, red colours, 24 contaminants had been considered at some point as σ Orionis members. I discuss how contamination may have affected previous work (especially related to disc frequencies) and the curious presence of lithium absorption in three M-dwarf proper motion contaminants. Finally, I classify the bright star HD 294297 as a late-F field dwarf unrelated to the cluster based on a new proper motion measurement. Conclusions. Although proper motions cannot be used to confirm membership in σ Orionis, they can be instead used to discard a number of cluster member candidates without spectroscopy.

show abstract

Section: Hd 294297mentioning

confidence: 99%

Stars and brown dwarfs in theσ Orionis cluster

Caballero¹

2010

A&A

View full text Add to dashboard Cite

show abstract

“…Haro & Moreno 1953;Walker 1969;Warren & Hesser 1978;Brown et al 1994;Sterzik et al 1995;de Zeeuw et al 1999;Briceño et al 2001). The youngest regions, including Alnitak (ζ Ori), which illuminates the Flame Nebula (NGC 2024), and σ Ori, which illuminates the Horsehead Nebula (Barnard 33 and IC 434), are to the east of the Belt and have ages of 1 to 5 Ma.…”

Section: Introductionmentioning

confidence: 99%

Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

2010

View full text Add to dashboard Cite

We look for high-amplitude variable young stars in the open clusters and associations of the Orion Belt. We use public data from the ASAS-3 Photometric V -band Catalogue of the All Sky Automated Survey, infrared photometry from the 2MASS and IRAS catalogues, proper motions, and the Aladin sky atlas to obtain a list of the most variable stars in a survey area of side 5 deg centred on the bright star Alnilam (ǫ Ori) in the centre of the Orion Belt. We identify 32 highly-variable stars, of which 16 had not been reported to vary before. They are mostly variable young stars and candidates (16) and background giants (8), but there are also field cataclysmic variables, contact binaries, and eclipsing binary candidates. Of the young stars, which typically are active Herbig Ae/Be and T Tauri stars with Hα emission and infrared flux excess, we discover four new variables and confirm the variability status of another two. Some of them belong to the well known σ Orionis cluster. Besides, six of the eight giants are new variables, and three are new periodic variables.

show abstract

“…He noted that "the proportion of earliest-type stars is always largest in the most concentrated subsystem" and "the degree of association with the interstellar matter decreases with increasing size and evolutionary stage." These subgroups studied by Blaauw and others (Crawford 1961;Warren and Hesser 1978) did not depend on the existence of highly evolved B and M supergiants, but o 140 130 120 110 100 I Fig. 2-The distribution over a section of the galactic plane of all O and early B-type stars for which both photometry and spectral types have been published.…”

Section: Introduction and Historymentioning

confidence: 92%

OB associations: Massive stars in context

Garmany¹

1994

PASP

View full text Add to dashboard Cite

ABSTRACT. Massive stars are important in a variety of contexts: individually they are examples of stars that undergo significant mass loss which is driven by line radiation pressure; as denizens of the Galaxy they play a significant role in the galactic recycling effort; as ensembles of stars they contain clues to massive star evolution in general and the question of supernova progenitors in particular. Finally, under extreme conditions of pathological star formation massive stars participate in the star burst phenomena seen in some galaxies. If we wish to understand star bursts, we must first understand locally observed variations in the mass spectrum. But all of these diverse areas of study rely on certain fundamental parameters of the stars themselves-here we include temperature, luminosity, mass, and chemical composition. And central to accurate determinations of these parameters are the distances to the stars. This review will focus on what is known about the loose clustering of massive stars termed OB associations. These associations contain many, but by no means all, of the stars with masses greater than 15Mq. Most of our knowledge of the stellar content of the OB associations in our own Galaxy is surprisingly sketchy due to their large angular size, but large-field CCD detectors are changing this. Magellanic Cloud associations can now be compared with OB associations in our own Galaxy, and the initial mass function shows surprising variations. The physical cause of these variations is still unknown. Another development is the study of embedded star clusters: infrared array detectors have been probing the buried stars in molecular clouds and finding an unexpectedly large population of these objects. Both these young IR clusters, and a sprinkling of evolved red supergiants, suggest that the star-formation history of OB associations may be more complicated than we have supposed.

show abstract

A photometric study of the Orion OB 1 association. III - Subgroup analyses

Cited by 118 publications

References 0 publications

Stars and brown dwarfs in theσ Orionis cluster

Stars and brown dwarfs in theσ Orionis cluster

Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

OB associations: Massive stars in context

Contact Info

Product

Resources

About