High-resolution spectroscopy investigation of classical Cepheids and main-sequence B-stars in galactic open clusters and associations

2000 ◽  
Author(s):  
Igor A. Usenko ◽  
Valery V. Kovtyukh ◽  
Sergej M. Andrievsky ◽  
Valentina G. Klochkova ◽  
Vladimir E. Panchuk
Keyword(s):  
High Resolution ◽  
Main Sequence ◽  
Open Clusters ◽  
High Resolution Spectroscopy ◽  
Open Clusters And Associations ◽  
B Stars ◽  
Classical Cepheids

scholarly journals Cepheid distances from the Baade–Wesselink method

2012 ◽  
Vol 8 (S289) ◽  
pp. 138-144 ◽  
Author(s):  
Wolfgang Gieren ◽  
Jesper Storm ◽  
Nicolas Nardetto ◽  
Alexandre Gallenne ◽  
Grzegorz Pietrzyński ◽  
...  
Keyword(s):  
Excellent Agreement ◽  
Surface Brightness ◽  
Recent Progress ◽  
Main Sequence ◽  
Near Infrared ◽  
Open Cluster ◽  
Open Clusters ◽  
Distance Scale ◽  
Systematic Uncertainties ◽  
Classical Cepheids

AbstractRecent progress on Baade–Wesselink (BW)-type techniques to determine the distances to classical Cepheids is reviewed. Particular emphasis is placed on the near-infrared surface-brightness (IRSB) version of the BW method. Its most recent calibration is described and shown to be capable of yielding individual Cepheid distances accurate to 6%, including systematic uncertainties. Cepheid distances from the IRSB method are compared to those determined from open cluster zero-age main-sequence fitting for Cepheids located in Galactic open clusters, yielding excellent agreement between the IRSB and cluster Cepheid distance scales. Results for the Cepheid period–luminosity (PL) relation in near-infrared and optical bands based on IRSB distances and the question of the universality of the Cepheid PL relation are discussed. Results from other implementations of the BW method are compared to the IRSB distance scale and possible reasons for discrepancies are identified.

scholarly journals Be Phenomena in Young Early-type Stars: Various Forms of Interaction between the Star and the Circumstellar Gaseous Envelope

2000 ◽  
Vol 175 ◽  
pp. 344-347
Author(s):  
M. Pogodin
Keyword(s):  
High Resolution ◽  
Stellar Wind ◽  
Main Sequence ◽  
Stellar Surface ◽  
High Resolution Spectroscopy ◽  
Evolutionary Status ◽  
Be Stars ◽  
Early Type ◽  
Early Type Stars ◽  
Gaseous Envelope

AbstractNew results of high-resolution spectroscopy of four pre-main sequence Ae/Be stars are presented. An analysis of parameters of lines originating in different regions of the circumstellar (CS) envelope (Hα, Hβ, He I 5876, DNal) allows to reconstruct a picture of the interaction between the star and the CS environment which can be displayed in different forms. At least two separate processes seem to impact the structural and kinematical properties of the envelope: the stellar wind from the stellar surface and the matter infall onto the star from the CS media. A possible relation between these two phenomena is discussed in the framework of different models. Some similarity between observational phenomena in Herbig Ae/Be and classical Be stars is noted in spite of their difference in evolutionary status.

scholarly journals Metallicities for 13 nearby open clusters from high-resolution spectroscopy of dwarf and giant stars

2008 ◽  
Vol 493 (1) ◽  
pp. 309-316 ◽  
Author(s):  
N. C. Santos ◽  
C. Lovis ◽  
G. Pace ◽  
J. Melendez ◽  
D. Naef
Keyword(s):  
High Resolution ◽  
Open Clusters ◽  
High Resolution Spectroscopy ◽  
Giant Stars

High-resolution spectroscopy of red giants and ‘yellow stragglers’ in the southern open cluster NGC 2539

2020 ◽  
Vol 494 (1) ◽  
pp. 1470-1489
Author(s):  
Cintia F Martinez ◽  
N Holanda ◽  
C B Pereira ◽  
N A Drake
Keyword(s):  
High Resolution ◽  
Open Cluster ◽  
Open Clusters ◽  
Solar Neighborhood ◽  
Spectroscopic Binaries ◽  
High Resolution Spectroscopy ◽  
Red Giants ◽  
Light Elements ◽  
Abundance Pattern ◽  
Solar Metallicity

ABSTRACT We present a detailed high-resolution spectroscopic analysis of 12 red giant stars, in single and binaries or multiples systems, classified as members of the intermediate-age (631 Myr) open cluster NGC 2539. We used FEROS echelle spectra and the standard LTE analysis to derive the atmospheric parameters for the stars and the abundance ratios of light elements (Li, C, N), light odd-Z elements (Na, Al), α-elements (Mg, Si, Ca, Ti), Fe-group elements (Cr, Fe, Ni), and n-capture elements (Y, Zr, Ce, Nd, Eu). Our results show that the sample star of NGC 2539 has low projected rotational velocities and an almost solar metallicity, with a mean of [Fe/H] = −0.03 ± 0.07 dex. The abundance pattern displays for the analyzed stars are, in general, similar to those presented by solar neighborhood stars, including giant members of others open clusters. In particular, light elements and Na abundance pattern shows anomalies resulting from the appearance of enriched material on the stellar surface, produced by mechanisms like the first dredge-up and/or thermohaline and rotation-induced mixing. We also identified two of the spectroscopic binaries of our sample as ‘yellow stragglers’ and we determined the nature of their companions.

scholarly journals Metallicity and v sin i of B Stars in Galactic Open Clusters: is there any Correlation?

2004 ◽  
Vol 215 ◽  
pp. 71-72
Author(s):  
F. Royer ◽  
C. Melo ◽  
J.-C. Mermilliod ◽  
P. North ◽  
J. D. do Nascimento ◽  
...  
Keyword(s):  
Main Sequence ◽  
Stellar Mass ◽  
Open Clusters ◽  
B Stars ◽  
Galactic Clusters ◽  
Larger Sample

We discuss the v sin i distributions of main sequence B stars in galactic clusters in relation to stellar luminosity and to cluster metallicity. We show that evolutionary effects and/or dependence of initial v sin i distribution on stellar mass are important, so that a much larger sample and a wider metallicity range are required to detect any possible metallicity effect beyond doubt.

scholarly journals Spectroscopic surveillance of the variable Herbig Ae star AB Aur

1986 ◽  
Vol 118 ◽  
pp. 443-445 ◽  
Author(s):  
U. Finkenzeller ◽  
J.G.V. Schiffer ◽  
H. Mandel
Keyword(s):  
High Resolution ◽  
Spectral Type ◽  
Main Sequence ◽  
High Resolution Spectroscopy ◽  
Rotational Period ◽  
Short Term ◽  
Stellar Radius ◽  
Rotational Modulation ◽  
Outer Atmosphere

AB Aur = HD 31293 = BD + 300741 = MWC 93 = HRC 78n is one of the brightest members of a class of pre-main sequence objects introduced by G. Herbig in 1960. The star is characterized by a spectral type of AOVe, L/L⊙ = 70, mv = 7.2 mag, v sini = 140 km/s, and d = 140 pc. Assuming a stellar radius of a main sequence dwarf R/R⊙ = 3.0, one can estimate the rotational period to be on the order of 28 hours if we see the system edge on. Previous work (Praderie et al. (1985) and Finkenzeller (1983)) has focused on high resolution spectroscopy and shown that AB Aur is subject to short term variations. Finkenzeller's observations have indicated that the emission features can disappear completely within a day. Praderie et al. found evidence of a rotational modulation (45 ± 6 hours) of the MgII λ 2795 and FeII UV lines which is interpreted as due to a non-axisymmetric wind interacting with the outer atmosphere.

scholarly journals New Homogeneous v sin i Determinations for B Stars in Galactic Open Clusters

2004 ◽  
Vol 215 ◽  
pp. 69-70 ◽  
Author(s):  
P. North ◽  
F. Royer ◽  
C. Melo ◽  
J. R. de Medeiros ◽  
J. D. do Nascimento ◽  
...  
Keyword(s):  
Least Squares ◽  
Main Sequence ◽  
Open Clusters ◽  
B Stars ◽  
Synthetic Spectra ◽  
Least Squares Fit ◽  
Galactic Clusters

We present new observations of projected rotational velocities of main sequence B stars in the galactic clusters NGC 2439, NGC 3293, NGC 3766, NGC 4755, NGC 7160 and h & χ Persei. 257 stars have been observed with three instruments, 207 of which are presented here. Projected rotational velocities have been determined by least-squares fit to synthetic spectra. Our v sin i scale is compared with that of Slettebak et al. (1975).

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