scholarly journals Search for Pulsational Instability among h Persei Stars

1995 ◽  
Vol 155 ◽  
pp. 299-300
Author(s):  
J. Krzesinski
Keyword(s):  
Northern Hemisphere ◽  
Open Clusters ◽  
Age Group ◽  
Be Stars ◽  
Double Cluster

AbstractThe northern-hemisphere double cluster h and χ Persei is one of the richest young open clusters. At least half of the brightest stars in the cluster appear to be variables and most of them axe Be stars. Till now there was no evidence for the presence of β Cephei stars in the cluster. It is remarkable that the similar age southern cluster NGC 3293 and other clusters belonging to the same age group are documented as clusters in which β Cephei stars have been observed. In this work we report finding one suspected β Cephei-like object, basing on our own observations.

scholarly journals Variable Be Stars in h and χ Persei

1987 ◽  
Vol 92 ◽  
pp. 505-508
Author(s):  
C.L. Waelkens ◽  
P. Lampens ◽  
J. Cuypers ◽  
J. Denoyelle ◽  
D. Heynderickx ◽  
...  
Keyword(s):  
Age Groups ◽  
Variable Stars ◽  
Age Group ◽  
Be Stars ◽  
Stellar Content ◽  
Photometric Variability ◽  
Double Cluster

The double cluster h and χ Persei has since long been known to be rich in Be stars (Trumpler, 1926). It belongs to an age group in which various types of variable stars occur (Mermilliod, 1981). Other clusters of this age group are NGC 3293, the cluster that is richest in β Cephei variables (Balona and Engelbrecht, 1983), IC 2581, NGC 4755, and NGC 6871. The comparison of the characteristics of variable stars in all these clusters and in clusters of other age groups could reveal to which extent the cluster stellar content is determined by age and by other parameters, such as galactic location, and so metallicity. Since h and χ Persei are very rich clusters that have not yet been studied intensively as far as stellar variability is concerned (Percy, 1972), we have undertaken a study of the photometric variability of the brightest stars in the double cluster. Our first interest was to detect β Cephei variables, but it rapidly turned out that the double cluster contains a considerable amount of highly variable Be stars.

scholarly journals Main-sequence broadening, Be stars, and stellar rotation inhand χ Persei

1994 ◽  
Vol 162 ◽  
pp. 151-152
Author(s):  
J. Denoyelle ◽  
C. Aerts ◽  
C. Waelkens
Keyword(s):  
Main Sequence ◽  
Large Fraction ◽  
Variable Stars ◽  
Theoretical Studies ◽  
Be Stars ◽  
Stellar Rotation ◽  
B Stars ◽  
Fundamental Parameters ◽  
Magnitude Diagram ◽  
Double Cluster

The double cluster h andxPersei is one of the richest clusters containing early-B stars, and therefore is important for observational and theoretical studies on the fundamental parameters of massive stars. The colour-magnitude diagram of the double cluster shows an important scatter (see Figure 1). It has long been known thathandxPersei are extremely rich in Be stars (Slettebak 1968). Our previous contention (Waelkens et al. 1990) that the large-amplitude variable stars we discovered are also Be stars, could be confirmed for a few objects. Rotation velocities for stars inhandxPersei are usually high, which is not surprising in view of the large fraction of Be stars.

scholarly journals Substructure and halo population of Double Cluster h and χ Persei

2019 ◽  
Vol 624 ◽  
pp. A34 ◽  
Author(s):  
Jing Zhong ◽  
Li Chen ◽  
M. B. N. Kouwenhoven ◽  
Lu Li ◽  
Zhengyi Shao ◽  
...  
Keyword(s):  
Parameter Space ◽  
Spatial Scales ◽  
Open Clusters ◽  
Halo Structure ◽  
Internal Motions ◽  
Halo Stars ◽  
Physical Scale ◽  
Cluster Cores ◽  
The Impact ◽  
Double Cluster

Context. Gaia DR2 provides an ideal dataset to study the stellar populations of open clusters at larger spatial scales because the cluster member stars can be well identified by their location in the multidimensional observational parameter space with high precision parameter measurements. Aims. In order to study the stellar population and possible substructures in the outskirts of Double Cluster h and χ Persei, we use Gaia DR2 data in a sky area of about 7.5° in radius around the Double Cluster cores. Methods. We identified member stars using various criteria, including their kinematics (namely, proper motion), individual parallaxes, and photometric properties. A total of 2186 member stars in the parameter space were identified as members. Results. Based on the spatial distribution of the member stars, we find an extended halo structure of h and χ Persei about six to eight times larger than their core radii. We report the discovery of filamentary substructures extending to about 200 pc away from the Double Cluster. The tangential velocities of these distant substructures suggest that they are more likely to be remnants of primordial structures, instead of a tidally disrupted stream from the cluster cores. Moreover, internal kinematic analysis indicates that halo stars seem to experience a dynamic stretching in the RA direction, while the impact of the core components is relatively negligible. This work also suggests that the physical scale and internal motions of young massive star clusters may be more complex than previously thought.

scholarly journals Abundances of Be Stars in Very Young Open Clusters

2000 ◽  
Vol 175 ◽  
pp. 59-62 ◽  
Author(s):  
A. Marco ◽  
G. Bernabeu ◽  
J.M. Torrejón ◽  
J.J. Rodes ◽  
J. Fabregat
Keyword(s):  
Open Clusters ◽  
Be Stars ◽  
Ccd Photometry ◽  
The Galaxy

AbstractWe present here standard uvbyβ CCD photometry for five open clusters of the Galaxy in order to determine abundances of Be stars, as a function of age.

scholarly journals Composite Colour-Magnitude and Colour-Colour Diagrams for Be Stars in Open Clusters

1982 ◽  
Vol 98 ◽  
pp. 23-26
Author(s):  
J.-C. Mermilliod
Keyword(s):  
Age Groups ◽  
Open Clusters ◽  
Be Stars ◽  
Photoelectric Photometry ◽  
Absolute Magnitudes ◽  
Colour Indices

By the end of 1980, the total number of Be stars discovered in the field of open clusters amounted to 180 stars distributed in 60 clusters. Among these, 110 Be stars belong to 32 clusters included in the sample I studied, which contains 75 open clusters younger than the Hyades. But only 88 stars with complete UBV photoelectric photometry have been taken into consideration here. The concept of age groups, defined elsewhere (Mermilliod 1981a), is used throughout the present analysis, as well as the new estimate of the colour excesses and distance moduli I obtained for these 32 clusters. Under the assumption of uniform reddening across the clusters, absolute magnitudes and dereddened colour indices have been calculated for the 88 Be stars.

scholarly journals VARIABILITY OF Be STARS IN SOUTHERN OPEN CLUSTERS

2009 ◽  
Vol 700 (2) ◽  
pp. 1216-1232 ◽  
Author(s):  
M. Virginia McSwain ◽  
Wenjin Huang ◽  
Douglas R. Gies
Keyword(s):  
Open Clusters ◽  
Be Stars

scholarly journals Be stars in open clusters. I. uvby $ ^{\bf \beta}$ photometry

1996 ◽  
Vol 119 (2) ◽  
pp. 271-279 ◽  
Author(s):  
J. Fabregat ◽  
J. M. Torrejón ◽  
P. Reig ◽  
G. Bernabeu ◽  
J. Busquets ◽  
...  
Keyword(s):  
Open Clusters ◽  
Be Stars

scholarly journals Be stars in open clusters

1997 ◽  
Vol 124 (2) ◽  
pp. 329-347 ◽  
Author(s):  
J. M. Torrejón ◽  
J. Fabregat ◽  
G. Bernabeu ◽  
S. Alba
Keyword(s):  
Open Clusters ◽  
Be Stars

scholarly journals Be Star Surveys in Open Clusters with Balmer-line Photometry

2000 ◽  
Vol 175 ◽  
pp. 63-66
Author(s):  
Gemma Capilla ◽  
Juan Fabregat ◽  
Deborah Baines
Keyword(s):  
Emission Line ◽  
Main Sequence ◽  
Open Clusters ◽  
Balmer Line ◽  
Be Stars ◽  
Late Type ◽  
Efficient Tool ◽  
Be Star ◽  
Almost All ◽  
Evolutionary Interpretation

AbstractWe present CCD Hα and Hβ photometry of young open clusters. We show that the comparison of the α and β photometric indices provides an efficient tool for identifying emission line stars. We report on the discovery of several new Be stars.The preliminary results of our survey are the following: i. the younger clusters (age < 10 Myr) are almost lacking of Be stars, ii. clusters in the age interval 10–30 Myr are rich in Be stars. Almost all of them are of spectral types earlier than B5, while late-type Be stars are scarce. These results point towards an evolutionary interpretation of the Be phenomenon, in the sense that Be stars are close to the end of their main sequence lifetime.

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