Observations of H<i>α</i>, iron, and oxygen lines in B, Be, and shell stars

Saad, S. M.; Kubát, Jiřı́; Korčáková, Daniela; Koubský, P.; Škoda, Petr; Šlechta, M.; Kawka, A.; Budovičová, A.; Votruba, V.; Šarounová, L.; Nouh, M. I.

doi:10.1051/0004-6361:20041877

Cited by 9 publications

(7 citation statements)

References 17 publications

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“…For each star we report, the number of spectra collected, their classification (abs means absorption lines only), the projected equatorial rotational velocity as measured by us in our spectra, mass and radius as estimated from Drilling & Landolt (1999), peaks separation, critical velocity, equatorial velocity, inclination angle, base density at the stellar equator, and the estimated disk radius. In the last column we also reported the references of other similar catalogs in which spectra of the star have been published: 1) Hanuschik (1988); 2) Hanuschik et al (1996); 3) Hanuschik (1996); 4) Slettebak et al (1992); 5) Saad et al (2006); 6) Silaj et al (2010). (Hutchings 1970), where R represents the radial coordinate that has its origin at the center of the star, and V * rot denotes the actual rotational velocity at the stellar surface.…”

Section: Classification and Fit Of The Hα Line Profilesmentioning

confidence: 99%

Spectroscopic atlas of Hαand Hβin a sample of northern Be stars

Catanzaro

2013

A&A

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Context. Be stars are fast-rotating early-type emission line stars. It is generally assumed that observed emission is generated in a rotating disk-like envelope, as supported by the observed correlation between the stellar projected rotational velocity v sin i and the width of the emission lines. Then, high-resolution spectroscopic observations of Balmer lines profiles play an important role in putting constraints on Be stars modeling. Aims. We present Balmer lines spectroscopy for a sample of 48 Be stars. For most of them, Hα and Hβ have been observed more than two times, in a total period spanning almost two years between 2008 and 2009. Methods. Spectral synthesis of the Hα profile was performed following two steps: photospheric contribution was computed by using Kurucz's code ATLAS9 and SYNTHE, and disk emission was derived by the approach of Hummel & Vrancken (2000, A&A, 302, 751). Results. For 26 out of 48 stars, a modeling of the total Hα emission, i.e. photospheric absorption plus disk net emission, has been attempted. By this modeling we derived an estimation of the disk radius, as well as the inclination angle between the rotational axis with line of sight and the base density at the stellar equator. For the stars observed more than once, we also discuss the variability of Hα and Hβ for what concerns both the equivalent width and the spectral profile. We found 16 stars with variable equivalent width and 7 stars with clear signs of profile variations. Conclusions. For all the stars in our sample, we derive all the fundamental astrophysical quantities, such as, effective temperature, gravity, and projected rotational velocity. We found 13 stars whose equivalent width is variable with a confidence level greater than 80% and 7 object for which spectral profiles show change with time. According to the commonly used classification scheme, we classified 16 stars as belonging to class 1, 13 to class 2, 11 are shell stars, 6 objects do not show net emission, and 2 stars display transitions from class 1 and 2. For the class 1 stars, we confirm the correlation between v sin i and peak separation. Concerning the geometry of the disk, we derived the base density at the stellar equator, the radius, and the inclination angle between rotational axis and line of sight. The maximum concentration of stars occurs for disk dimensions ranging in the interval of 6 to 8 stellar radii and for inclination angles going from 23 • to 35 • .

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Section: Classification and Fit Of The Hα Line Profilesmentioning

confidence: 99%

Spectroscopic atlas of Hαand Hβin a sample of northern Be stars

Catanzaro

2013

A&A

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“…Hα and OI 7772 A° in absorption, FeII 5169 A° line shows weak absorption and FeII 7712 A°line is not visible [7].…”

Section: Resultsmentioning

confidence: 99%

“…It has been assigned to this group by [22] who demonstrated its variability in radial velocity with a single period of 0.1517 d and amplitude of 3.5 km/s. Hα is in sharp absorption [7]. Our spectrum for γ Peg cover only observations from 5850 A° to 8350 A° and we hope in future to collect observation for this star in a wider visible wavelengths to get more accurate results.…”

Section: Resultsmentioning

confidence: 99%

“…Morgan [21] establish η UMa as an "MK dagger type", a star whose spectrum has been carefully examined and used to define the MK system. [7].…”

Section: Resultsmentioning

confidence: 99%

“…The resolving power is R = 20000 which analogue to FWHM = 0.25 A°. Table 1 represents the list of observed objects and their published parameters, for details we refer to [7] and reference there in. …”

Section: Optical Spectramentioning

confidence: 99%

See 2 more Smart Citations

Model Atmosphere Analysis of Some B-Type Stars

Saad¹,

Nouh²

2011

IJAA

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We present model atmosphere analysis for a sample of B-type stars in optical region to obtain their fundamental parameters e.g. effective temperature, surface gravities, and rotational velocities. Approximate masses for the sample of stars under study are obtained by comparing the resulted effective temperatures and surface gravities with the evolutionary tracks. Comparison between these masses and the empirical effective temperatures-mass relation revealed good agreement.

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