A New Spectrum Variable: 5 Lacertae.

Hynek, J. A.

doi:10.1086/143974

Cited by 6 publications

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“…On the basis of unpublished Mt. Wilson radial velocities, Hynek (1938) had suggested that the radial velocity of HD 69479/80 is variable. In a major and very public-spirited effort, Abt (1970Abt ( , 1973 listed the radial velocities, measured from about 23,000 Mt.…”

Section: Radial Velocities and Orbit Of The Cool Starmentioning

confidence: 99%

Composite-Spectrum Binaries, Paper XXIII: HD 69479/80, a 90-day binary with a cool-giant primary

Griffin,

Griffin

2020

Preprint

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HD 69479/80 is a composite-spectrum binary whose components are a late-G giant and an early-A dwarf. The orbit has a period of only 91 days (which seems short for a system containing a cool giant with a radius of ∼13 solar radii), and a very small, but probably significantly non-zero, eccentricity. We separated the component spectra by a procedure of spectral subtraction, using a standard single giant spectrum as a template, and found the closest match to the spectrum of the cool component to be that of 15 Cyg (G8 III). We measured the radial velocity of the secondary component from each uncovered spectrum, solved the SB2 orbit for the system, and derived a mass ratio m1 / m2 of 1.318. Fitting synthetic spectra to the spectra of the secondary component indicated a T eff of 9250 K, log g = 3.75, and a rotational velocity of ∼90 km s −1 . We determined the difference in absolute magnitude, δV, between the component stars to be 1.07 mag, the late-type component being the brighter; we could thence calculate radii and luminosities for both components, plot their H-R diagram positions, and fit evolutionary tracks. The best-fitting tracks indicated masses of 2.9 M⊙ for the giant and 2.2 M⊙ for the dwarf, which was fully in keeping with the mass ratio given by the SB2 orbit. The track for the dwarf star confirms that this component has begun to evolve away from the ZAMS. Fitting the corresponding isochrone to those H-R diagram positions indicated a log (age) of the system of approximately 8.60 Gyr since the cool star evolved from the ZAMS, which is a little younger than the ages deduced for many cool giants. We also detected the λ 6707-Å lithium line in the spectrum of the giant component, thus adding to the evidence that it is near the start of its primary ascent of the red-giant branch.

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Section: Radial Velocities and Orbit Of The Cool Starmentioning

confidence: 99%

Composite-Spectrum Binaries, Paper XXIII: HD 69479/80, a 90-day binary with a cool-giant primary

Griffin,

Griffin

2020

Preprint

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“…Therefore, it seems likely that the radial velocity of the K star does not change by any appreciable amount above intrinsic observational and measuring errors or the intrinsic velocity variation of the K bright giant star. Hynek (1938) noted that the spectrum of the K star was composite, with the sharp early-type Ca n K-line of an A0 star showing through the haze of the broad-blended K-line of the K primary. This observer has confirmed the presence of the characteristic Balmer series of hydrogen of a late-B star to the violet of the Ca n K-line and on well-exposed plates, was able to measure the radial velocities of several of these fairly sharp lines of the secondary of the composite spectrum.…”

Section: The Radial Velocity Of the K Primary Starmentioning

confidence: 99%

“…The ß 1 Cygni system (HR 7417; ADS 12540; m v = 3.24) has long been known to be triple in character; consisting of a K3 II primary (Bidelman 1958), a B8 V (Johnson and Morgan 1953) visual companion (HR 7418; m v -5.11) at a separation of 34.8 arc seconds, and a B9 V (Hynek 1938;Bahng 1958) secondary which forms a composite spectrum with the primary K star. Radial velocities of the stars of the visual pair had been obtained as early as 1898 (e.g., Campbell 1919;Adams and Joy 1923) and it had been speculated by Campbell (1919) that the velocity of the K star was slowly variable over time.…”

Section: Introductionmentioning

confidence: 99%

The 'orbit' of Beta 1 Cygni

Hendry

1981

PASP

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The resolution of ß 1 Cyg by the technique of speckle interferometry (and later by visual means) has led to speculations of a recent increase in separation between the two stars of the composite spectrum. Radial velocities from recently obtained spectra as well as those already in the literature have provided relatively complete coverage from 1898 to 1980 and show no essential change in the radial velocity of the K star or its B-star companion during this time, leading to the conclusion that either the period of ß 1 Cyg is considerably longer than suspected or that the two stars are physically unrelated. Inconsistencies between the speckle observations are commented upon.

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“…The variability in velocity and spectrum of 5 Lacertae 1 was announced by one of us in 1938. 2 The star has proved to be a spectroscopic binary system, and is noteworthy because of the large values of its period and eccentricity.…”

Section: Ohio Wesleyan Universitymentioning

confidence: 99%

The Composite-Spectrum Star 5 Lacertae

Hynek¹,

Stanger²

1959

PASP

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The variability in velocity and spectrum of 5 Lacertae 1 was announced by one of us in 1938. 2 The star has proved to be a spectroscopic binary system, and is noteworthy because of the large values of its period and eccentricity.For over 20 years the radial velocity of the star had been considered constant (-12 km/sec) ; then in a period of four years or less it rose to its maximum value (about +20 km/sec). Because it had been listed in the Lick Catalogue as a constant-velocity star, only a few spectrograms taken near the critical epoch exist. Since then the star has been under periodic observation with the prism spectrograph (27 Â/mm at HÔ) at the Perkins Observatory, and elsewhere.The spectrum is composite (K5 lb, AO). The fainter continuous spectrum of the companion is plainly evident in the violet portion of the spectrum, filling in the lines of the KS primary. The secondary has been classed as AO by the manner in which the broad K line of the primary is filled in, or "washed out," by the continuous spectrum of the companion. Only a secondary close to AO in spectral class, with a strong Hs line, could produce by superposition with a K5 both a faint broad K line and a strong broad H line in the composite spectrum, owing to the nearly coincident wavelengths of H and He.Sharp H and K lines, with emission edges, appear superposed on the already composite H and K lines. These may not come from the secondary, however, as their radial velocities are erratic.There is good evidence that these lines arise in an expanding gas mass surrounding the primary.Further, the sharp K line is not always filled in by the spectrum of the secondary, and the sharp H line, which occurs in the * On leave from Ohio State University. 310

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A New Spectrum Variable: 5 Lacertae.

Cited by 6 publications

References 0 publications

Composite-Spectrum Binaries, Paper XXIII: HD 69479/80, a 90-day binary with a cool-giant primary

Composite-Spectrum Binaries, Paper XXIII: HD 69479/80, a 90-day binary with a cool-giant primary

The 'orbit' of Beta 1 Cygni

The Composite-Spectrum Star 5 Lacertae

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