Detection of an H$alpha$ Zeeman pattern in the cool magnetic white dwarf G99-47

Journal Article · Mon Dec 15 04:00:00 EST 1975 · Astrophys. J., Lett., v. 202, no. 3, pp. L139-L143

OSTI ID:4050484

Liebert, J; Angel, J R.P.; Landstreet, J D

An apparent H$alpha$ absorption feature has been detected in image tube scans of the cool magnetic white dwarf G99-47, previously classified as DC (featureless). The broad approx.2.5 A EW line is centered some 21 A shortword from the normal H$alpha$ position. This lines is interpreted as the $pi$ component of H$alpha$-shifted by the quadratic Zeeman effect in a surface field of approx.15x10$sup 6$ gauss. This interpretation is supported by the detection of the characteristic circular polarization of the sigma components at +-350 A in data obtained with the multichannel spectrophotometer. Both results are fitted well by a simple, centered dipole model with a mean longitudinal field of 5.6x10$sup 6$ gauss. However, the longitudinal field strength indicated from the continuum circular dichroism theory is about a factor of four smaller. The strength of the H$alpha$ absorption and absence of other detectable Balmer and Ca ii lines are consistent with G99-47 being a very cool, metal-poor DA star. (AIP)

• Research Organization: Department of Astronomy, University of California at Berkeley
• NSA Number: NSA-33-024033
• OSTI ID: 4050484
• Journal Information: Astrophys. J., Lett., v. 202, no. 3, pp. L139-L143, Journal Name: Astrophys. J., Lett., v. 202, no. 3, pp. L139-L143; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

*WHITE DWARF STARS-- ZEEMAN EFFECT
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CALCIUM
LYMAN LINES
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SPECTRA