Secondary stars in CVs – the observational picture

Beuermann, K.

doi:10.1016/s1387-6473(00)00020-8

Cited by 19 publications

(27 citation statements)

References 24 publications

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“…We use the re-calibration of the K-band surface brightness of late type stars by Beuermann (2000) which yields S K = 4.37 ± 0.22 for a dwarf of spectral type M3-5 and near-solar composition. With K = 12.19 .…”

Section: Distance Of Ex Hydraementioning

confidence: 99%

Multi-wavelength spectrophotometry of EX Hydrae

Eisenbart

Beuermann

Reinsch

et al. 2002

A&A

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Abstract. We present phase-resolved infrared and optical spectrophotometry of the intermediate polar EX Hya supplemented by archival ultraviolet data. The spin-modulated emission from the accretion funnel and the emission from the accretion disk or ring contain substantial optically thin components. The white dwarf dominates the unmodulated flux in the ultraviolet and is identified by numerous absorption lines. Metal absorption in the accretion curtain may add to the observed spectral features. The secondary star is of spectral type M4 ± 1 and is detected by its ellipsoidal modulation. We derive a distance of 65 ± 11 pc which makes EX Hydrae one of the closest cataclysmic variables with a known distance. The luminosity derived from the integrated overall spectral energy distribution is 3 × 10 32 erg s −1 . The accretion rate of 3 × 10 15 g s −1 (for an 0.6 M white dwarf) is in reasonable agreement with the rates expected from angular momentum loss by gravitational radiation and from the observed spin-up of the white dwarf.

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Section: Distance Of Ex Hydraementioning

confidence: 99%

Multi-wavelength spectrophotometry of EX Hydrae

Eisenbart

Beuermann

Reinsch

et al. 2002

A&A

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“…This method assumes that all K-band emission originates from the secondary star. Almost all secondary stars in CVs lie on or near the ZAMS (Zero Age Main Sequence) for near-solar metallicity within the uncertainties (Warner, 1995;Beuermann et al, 1998;Beuermann, 2000;Kolb & Baraffe, 2000). However, if one tries to measure the absolute magnitude of the secondary star, contributions to the light from the other components contaminate the results.…”

Section: Introductionmentioning

confidence: 97%

A new absolute magnitude calibration with 2MASS for cataclysmic variables

Bilir

et al. 2007

New Astronomy

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Using reliable trigonometric measurements, we find that the absolute magnitude of cataclysmic variables depends on the orbital period and de-reddened (J − H) 0 and (H −K s ) 0 colours of 2MASS (Two Micron All Sky Survey) photometric system. The calibration equation covers the ranges 0.03256 and 2.0 < M J < 11.7; It is based on trigonometric parallaxes with relative errors of (σ π /π) ≤ 0.4. By using the period-luminositycolours (PLCs) relation, we estimated the distances of cataclysmic variables with orbital periods and 2MASS observations and compared them with distances found from other methods. We suggest that the PLCs relation can be a useful statistical tool to estimate the distances of cataclysmic variables.

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“…Using a sample of main sequence stars with appropriate metallicity, the F λ or S λ for different photometric bands have been calibrated as functions of color or spectral type (Beuermann et al 1999;Beuermann 2000Beuermann , 2006. The distance is found to be proportional to the stellar radius of the secondary star which is given by Roche geometry.…”

Section: Distance Of V1309 Orimentioning

confidence: 99%

“…and with a 4π average magnitude of the unheated secondary of 2 The distance of 745 pc quoted by Beuermann (2000) did not include dereddening and was based on an a slightly different calibration of F 7500 . K = 13.48, its absolute K-band magnitude would be M K = 4.59 +0.10 −0.19 , where the errors refer to the full range of secondary masses of 0.4 to 0.6 M , with 0.46 M the nominal mass.…”

Section: Distance Of V1309 Orimentioning

confidence: 99%

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The secondary star and distance of the polar V1309 Orionis

Reinsch¹,

Kim²,

Beuermann³

2006

A&A

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Context. The first phase-resolved JHK light curves of the eclipsing polar (AM Herculis binary) V1309 Ori are presented and interpreted. Aims. We separate the contributions from the secondary star and from other sources with the aim of determining a photometric distance. Methods. Simple model calculations show that the accretion stream and the cyclotron source on the accreting white dwarf are minor contributors to the infrared light, allowing an accurate determination of spectral type and absolute flux of the secondary star.Results. The unilluminated backside of the secondary star as seen in eclipse has spectral type dM0 to dM0+. Its dereddened magnitude is K = 13.58 at orbital phase φ = 0 (eclipse). Using the calibrated surface brightness of M-stars and the published mass of the secondary, M 2 = 0.46 M , we obtain a distance d = 600 ± 25 pc which scales as M 1/2 2 . The radius of the Roche-lobe filling secondary exceeds the main-sequence radius of an M0 star by 21 +11 −6 %. Conclusions. The debated origin of the infrared light of V1309 Ori has been settled in favor of the secondary star as the main contributor and an accurate distance has been derived that will place estimates of the luminosity and synchronization time scale on a more secure basis.

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Secondary stars in CVs – the observational picture

Cited by 19 publications

References 24 publications

Multi-wavelength spectrophotometry of EX Hydrae

Multi-wavelength spectrophotometry of EX Hydrae

A new absolute magnitude calibration with 2MASS for cataclysmic variables

The secondary star and distance of the polar V1309 Orionis

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