Physical Parameters of the Massive Multiple System Eta Orionis

Waelkens, Christoffel; Lampens, P.

doi:10.1007/978-94-009-2987-6_17

Cited by 9 publications

(9 citation statements)

References 4 publications

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“…η Ori AaAb+B differs from the other four systems in this paper in not including an O star (it had not appeared in a GOSSS paper before) and in having a complex photometric curve. One photometric period is 7.989255 d long and is associated with the eclipsing binary Aa (unresolved components Aa1+Aa2, Waelkens & Lampens 1988;De Mey et al 1996) while a second, shorter one, has an unclear origin. It has been proposed that it originates in B being another eclipsing binary with a 0.864 d period (Waelkens & Lampens 1988;Lee et al 1993), but it has not been proved conclusively, as other alternatives are possible and no spectrum of B separated from AaAb had been previously published.…”

Section: Resultsmentioning

confidence: 99%

Lucky Spectroscopy, an equivalent technique to Lucky Imaging

Apellániz

Barbá

Fariña³

et al. 2018

A&A

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Context. Many massive stars have nearby companions whose presence hamper their characterization through spectroscopy. Aims. We want to obtain spatially resolved spectroscopy of close massive visual binaries to derive their spectral types. Methods. We obtained a large number of short long-slit spectroscopic exposures of five close binaries under good seeing conditions. We selected those with the best characteristics, extracted the spectra using multiple-profile fitting, and combined the results to derive spatially separated spectra. Results. We demonstrate the usefulness of Lucky Spectroscopy by presenting the spatially resolved spectra of the components of each system, in two cases with separations of only ~0.′′3. Those are δ Ori Aa+Ab (resolved in the optical for the first time) and σ Ori AaAb+B (first time ever resolved). We also spatially resolve 15 Mon AaAb+B, ζ Ori AaAb+B (both previously resolved with GOSSS, the Galactic O-Star Spectroscopic Survey), and η Ori AaAb+B, a system with two spectroscopic B+B binaries and a fifth visual component. The systems have in common that they are composed of an inner pair of slow rotators orbited by one or more fast rotators, a characteristic that could have consequences for the theories of massive star formation.

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Section: Resultsmentioning

confidence: 99%

Lucky Spectroscopy, an equivalent technique to Lucky Imaging

Apellániz

Barbá

Fariña³

et al. 2018

A&A

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“…HD 35411 ( Ori).-A period at 0.43208 day was found by Waelkens & Lampens (1988) in their photometric data. It is doubtful if it originates from pulsation.…”

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confidence: 88%

Catalog of Galactic β Cephei Stars

Stankov

Handler

2005

ASTROPHYS J SUPPL S

213

261

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We present an extensive and up-to-date catalog of Galactic Cephei stars. This catalog is intended to give a comprehensive overview of observational characteristics of all known Cephei stars, covering information until 2004 June. Ninety-three stars could be confirmed to be Cephei stars. We use data from more than 250 papers published over the last nearly 100 years, and we provide over 45 notes on individual stars. For some stars we reanalyzed published data or conducted our own analyses. Sixty-one stars were rejected from the final Cephei list, and 77 stars are suspected to be Cephei stars. A list of critically selected pulsation frequencies for confirmed Cephei stars is also presented. We analyze the Cephei stars as a group, such as the distributions of their spectral types, projected rotational velocities, radial velocities, pulsation periods, and Galactic coordinates. We confirm that the majority of the Cephei stars are multiperiodic pulsators. We show that, besides two exceptions, the Cephei stars with high pulsation amplitudes are slow rotators. Those higher amplitude stars have angular rotational velocities in the same range as the high-amplitude Scuti stars (P rot k 3 days).We construct a theoretical HR diagram that suggests that almost all 93 Cephei stars are main-sequence objects. We discuss the observational boundaries of Cephei pulsation and the physical parameters of the stars. We corroborate that the excited pulsation modes are near to the radial fundamental mode in frequency and we show that the mass distribution of the stars peaks at 12 M . We point out that the theoretical instability strip of the Cephei stars is filled neither at the cool nor at the hot end and attempt to explain this observation.

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“…Of the 112 previously known β Cephei stars, there were four components of eclipsing systems (see : 16 (EN) Lac (Jerzykiewicz et al 1978;Pigulski & Jerzykiewicz 1988), V381 Car in NGC 3293 (Engelbrecht & Balona 1986;Jerzykiewicz & Sterken 1992;Freyhammer et al 2005), η Ori (Kuntz & Stebbins 1916;Waelkens & Lampens 1988;De Mey et al 1996), and λ Sco (Shobbrook & Lomb 1972;Uytterhoeven et al 2004;Bruntt & Buzasi 2006).…”

Section: Components Of Detached Eclipsing Binariesmentioning

confidence: 99%

β Cephei stars in the ASAS-3 data

Pigulski¹,

Pojmański²

2007

A&A

126

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Context. The β Cephei stars have been studied for over a hundred years. Despite this, many interesting problems related to this class of variable stars remain unsolved. Fortunately, these stars seem to be well-suited to asteroseismology. Hence, the results of seismic analysis of β Cephei stars should help us to better understand pulsations and the main sequence evolution of massive stars, particularly the effect of rotation on mode excitation and internal structure. It is therefore extremely important to increase the sample of known β Cephei stars and select targets that are useful for asteroseismology. Aims. We analysed ASAS-3 photometry of bright early-type stars with the goal of finding new β Cephei stars. We were particularly interested in β Cephei stars that would be good for seismic analysis, i.e., stars that (i) have a large number of excited modes; (ii) show rotationally split modes; (iii) are components of eclipsing binary systems; (iv) have low-frequency modes, that is, are hybrid β Cephei/SPB stars. Methods. Our study was made with a homogeneous sample of over 4100 stars having MK spectral type B5 or earlier. For these stars, the ASAS-3 photometry was analysed by means of a Fourier periodogram. Results. We have discovered 103 β Cephei stars, nearly doubling the number of previously known stars of this type. Among these stars, four are components of eclipsing binaries, seven have modes equidistant or nearly equidistant in frequency. In addition, we found five β Cephei stars that show low-frequency periodic variations, very likely due to pulsations. We therefore regard them as candidate hybrid β Cephei/SPB pulsators. All these stars are potentially very useful for seismic modeling. Moreover, we found β Cephei-type pulsations in three late O-type stars and fast period changes in one, HD 168050.

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Physical Parameters of the Massive Multiple System Eta Orionis

Cited by 9 publications

References 4 publications

Lucky Spectroscopy, an equivalent technique to Lucky Imaging

Lucky Spectroscopy, an equivalent technique to Lucky Imaging

Catalog of Galactic β Cephei Stars

β Cephei stars in the ASAS-3 data

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