HD 169981 -an overlooked photometric binary?

Lehmann, H.; Hildebrandt, G.; Panov, K. P.; Scholz, G.

doi:10.1051/0004-6361:20010641

Cited by 5 publications

(6 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the period search we used a modified Scargle diagram (see Lehmann et al 1999) in which the ordinate S gives the reduction in the sum of squares. It is S = 1 − σ/σ 0 , where σ is the variance of the residuals of a sine-wave fit and σ 0 is the total variance of the data.…”

Section: Search For Short-term Periodsmentioning

confidence: 99%

The eclipsing binary star RZ Cas

Lehmann

Mkrtichian

2003

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. In a first report on the results of a multi-site campaign in 2001 of photometric and spectroscopic observations of the active semi-detached Algol-type system RZ Cas, we concentrate on the radial velocity (RV) variations. Using weak absorption lines we obtain an improved orbital solution for both components. In the orbital RV curve we observe a strong, asymmetric rotation effect. For the first time we detect rapid spectroscopic multi-mode pulsations in an Algol system. Whereas the photometrically observed oscillations were dominated by monoperiodic pulsations at frequency 64. . Both modes show amplitude variations over the orbital phase with a a minimum at orbital phases φ = 0.6-0.8 and a maximum just after the primary minimum ( f 2 ) and at φ ≈ 0.25 ( f 1 ). The different shape of amplitude modulation of the f 1 and f 2 modes points to different (l, m) mode structures. The modulation itself can be explained by assuming a variable extinction due to gas streams and an inhomogeneous accretion annulus that weakens the light from different regions of the primary depending on its orbital position. This assumption is well supported by the gas density distribution obtained in preliminary hydrodynamic simulations. We found strong variations and cycle-to-cycle variable shapes of the orbital RV-curves of Balmer lines that have maximum magnitude in the Hα line indicating a strong variability of mass-transfer rates and a non-stationary circumbinary envelope.

show abstract

Section: Search For Short-term Periodsmentioning

confidence: 99%

The eclipsing binary star RZ Cas

Lehmann

Mkrtichian

2003

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…A detailed description of the periodogram and a discussion of its statistical properties can be found in Lehmann et al (1999). The program is used to search in the residuals of an assumed multiple frequency model for possible additional frequencies.…”

Section: Period Finding Techniquesmentioning

confidence: 99%

A new analysis of the radial velocity variations of the eclipsing and spectroscopic binary EN Lacertae

Lehmann¹,

Harmanec

Aerts³

et al. 2001

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. An analysis of 1236 new electronic spectra of the eclipsing binary EN Lac from four observatories and of 994 radial velocities (RV hereafter) from photographic spectra, published by several authors, has allowed us to disentangle the RV variations due to orbital motion and due to pulsations of the star. New, accurate orbital elements as well as precise values of the three pulsation periods, already known from the previous studies, were derived. The accuracy of the orbital solution has been substantially improved after the observed RV changes were properly prewhitened for the short-term oscillations. The amplitude of the dominant RV oscillation with a period of P1 = 0.d 16916703 was found to vary with a 74 year cycle. The amplitudes of the two other RV oscillations, having periods of P3 = 0.d 18173256 and P2 = 0. d 17085554, vary on much shorter time scales of 674 d and 331 d, respectively. The value of P2 derived here does not correspond to a one year alias of the value found by several authors from photometry but appears to be an intrinsic period. The time scales of the amplitude modulations found for P1 and P3 are in good agreement with previous photometric results. For the first time we present evidence of line profile variations of EN Lac. They correlate well with the short-term RV variations but they alternatively occur with periods corresponding either to the fundamental periods or to the first harmonics of P1 to P3. An analysis of the RV scatter along the orbital phase curve for the new spectra, obtained over a relatively short interval of time, gives some indication of a sharp increase of this scatter when the stars are approaching periastron. Since this could be a signature of forced oscillations, the effect is worth further study, though it appears rather marginal at present .

show abstract

“…Concerning HD 169981 the derived value of the surface gravity of log g = 3.3 favours the primary to be an early Atype giant as postulated by Lehmann et al (2001) in their binary model. Most of the investigated elements have solar-like abundances and only carbon and oxygen show some slight underabundance.…”

Section: Discussionmentioning

confidence: 62%

“…This HD 169981 8700 ± 100 3.3 ± 0.1 2.05 ± 0.1 2 Lyn 9310 ± 100 4.1 ± 0.1 2.00 ± 0.1 assumption is justified because the binary consists of an A-type primary and a K-type secondary having a significant difference in luminosity of about 6 mag (Lehmann et al 2001). …”

Section: Atmospheric Abundancesmentioning

confidence: 99%

Binary nature and elemental abundances of 2 Lyn and HD 169981

Lehmann

Егорова

Scholz³

et al. 2003

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. We analyse high-resolution spectrograms of the early A-type stars HD 169981 and 2 Lyn. For the spectroscopic and photometric binary HD 169981 we determine the abundances of certain chemical elements. The derived atmospheric parameters show the star to be an A giant. The abundances of the elements Mg, Si, Ti, Cr, and Fe are very close to solar, only C and O show slight underabundances. 2 Lyn has been primarily studied for the occurrence of radial velocity variations. The star is probably a spectroscopic binary with a period of about 3.6 years. Preliminary orbital elements are derived. The search for shorter radial velocity variations gives hints of periods of 69.2, 1.56 and 1.53 days. Both of the last-mentioned periods are in the order of the expected rotation period of the star. The stellar parameters are estimated and for certain elements we determined the abundances.

show abstract

HD 169981 -an overlooked photometric binary?

Cited by 5 publications

References 8 publications

The eclipsing binary star RZ Cas

The eclipsing binary star RZ Cas

A new analysis of the radial velocity variations of the eclipsing and spectroscopic binary EN Lacertae

Binary nature and elemental abundances of 2 Lyn and HD 169981

Contact Info

Product

Resources

About