On the Separation BT Balmer-Line Photometry on High and Low Luminosity Stars having H_alpha in Emission

Abt, Helmut A.; Golson, J. C.

doi:10.1086/148513

Cited by 24 publications

(8 citation statements)

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“…We believe that a plot of the Ha: index vs. the Uß index clearly separates the B-type super-giants from the ordinary B-type emission stars. This has already been shown by Andrews (1968) and by Abt and Golson (1966), on the basis of less data than presented here. Clearly, the Balmer lines are different for the two classes of stars.…”

Section: Discussionsupporting

confidence: 76%

Emission-line effects in H alpha, H beta, H gamma and UVBY photometry for B-type stars.

Crawford¹,

Barnes²,

Perry³

1975

PASP

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Section: Discussionsupporting

confidence: 76%

Emission-line effects in H alpha, H beta, H gamma and UVBY photometry for B-type stars.

Crawford¹,

Barnes²,

Perry³

1975

PASP

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“…This was done by means of an α index, defined as a difference between the magnitudes of a star through a narrow and a wide filter. Our filters and, consequently, the α index resembles those used by others, namely Abt & Golson (1966), Tebbe (1969), Feinstein (1974), Dachs & Schmidt-Kaler (1975), Claría & Escosteguy (1981), Strauss & Ducati (1981), and Goderya & Schmidt (1994). We made, however, no attempt to transform our α to that defined by others; it was left in Table 1.…”

Section: Hα Photometrymentioning

confidence: 99%

The young open cluster NGC 663 and its Be stars

Pigulski

Kopacki

Kołaczkowski

2001

A&A

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Abstract. We present new BV (RI)CHα photometry of the young open cluster NGC 663. The Hα photometry is complete down to magnitude RC = 15.4, corresponding to spectral type A5 for the cluster members. This allows detection of mild and strong Hα emission in all B-type stars in the cluster. In addition to the 22 Be stars known in the observed field of NGC 663, we discovered four new faint stars of this type. We find that Be stars in NGC 663 cover the whole range of the B spectral type. They are, however, most populous among stars with spectral types falling in the range between B0 and B3, where their fraction amounts to 31 ± 8%. Among B-type stars later than B3, Be stars are much less abundant: only 7 out of 101 observed stars, that is, 7 ± 3%, were detected. About 70% of the observed Be stars in NGC 663 show detectable variations of light. In the time interval covered by our observations, the ranges of the largest variations reach 0.4 mag in the IC band. By means of the isochrone fitting, we derived the cluster distance of 2.1 kpc, age of 20-25 Myr, and the mean colour excess E(R − I)C = 0.54 mag, with a ∼0.1 mag scatter due to differential reddening.

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“…It has long been known (e.g., Abt and Golson 1966) that the strength of the Hα emission in hot supergiants is correlated with the stellar luminosity. The potential of this fact for the use of these optically luminous stars as extragalactic distance indicators was greatly advanced when Kudritzki et al (1999a,b) developed the wind momentum -luminosity relationship (WLR).…”

Section: Introductionmentioning

confidence: 99%

A FIVE-YEAR SPECTROSCOPIC AND PHOTOMETRIC CAMPAIGN ON THE PROTOTYPICAL Α CYGNI VARIABLE AND a-Type SUPERGIANT STAR DENEB

Richardson

Morrison

Kryukova

et al. 2010

The Astronomical Journal

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Deneb is often considered the prototypical A-type supergiant, and is one of the visually most luminous stars in the Galaxy. A-type supergiants are potential extragalactic distance indicators, but the variability of these stars needs to be better characterized before this technique can be considered reliable. We analyzed 339 high resolution echelle spectra of Deneb obtained over the five-year span of 1997 through 2001 as well as 370 Strömgren photometric measurements obtained during the same time frame. Our spectroscopic analysis included dynamical spectra of the Hα profile, Hα equivalent widths, and radial velocities measured from Si II λλ 6347, 6371. Time-series analysis reveals no obvious cyclic behavior that proceeds through multiple observing seasons, although we found a suspected 40 day period in two, non-consecutive observing seasons. Some correlations are found between photometric and radial velocity data sets, and suggest radial pulsations at two epochs. No correlation is found between the variability of the Hα profiles and that of the radial velocities or the photometry. Lucy (1976) found evidence that Deneb was a long period single-lined spectroscopic binary star, but our data set shows no evidence for radial velocity variations caused by a binary companion.

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On the Separation BT Balmer-Line Photometry on High and Low Luminosity Stars having H_alpha in Emission

Cited by 24 publications

References 0 publications

Emission-line effects in H alpha, H beta, H gamma and UVBY photometry for B-type stars.

Emission-line effects in H alpha, H beta, H gamma and UVBY photometry for B-type stars.

The young open cluster NGC 663 and its Be stars

A FIVE-YEAR SPECTROSCOPIC AND PHOTOMETRIC CAMPAIGN ON THE PROTOTYPICAL Α CYGNI VARIABLE AND a-Type SUPERGIANT STAR DENEB

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