A radio and optical study of the active young F star HR 1817 (=HD 35850)
[ X ]
Tarih
2002
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
C S I R O Publishing
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
This paper presents the results of a multiwavelength observational study of the active young F-type star HR 1817. The star was monitored at 4.80 and 8.64 GHz over 2 x 12 h allocations with the Australia Telescope Compact Array on 8 and 9 December, 2000. The Anglo-Australian Telescope was used for simultaneous optical spectropolarimetry during a 2 h period on 9 December. The low levels of observed radio emission have characteristics that are similar to those seen in other active stars, and a gyrosynchrotron mechanism is proposed to explain them; this is supported by the relatively low fractions of circular polarisation measured in HR 1817. Comparison of the emissions from 4.80 and 8.64 GHz shows a very strong cross-correlation peak, indicative of a common origin, although the shift of this peak indicates that 8.64 GHz variations tend to precede those at 4.80 GHz by, typically, similar to20 min. The optical spectropolarimetry reveals polarisation signals characteristic of surface magnetic fields, with profile changes indicating a complex dynamo-type magnetic topology is present on the star. This result makes HR 1817 the star with the earliest spectral type on which dynamo magnetic fields have been detected directly up to now.
Açıklama
Anahtar Kelimeler
stars : activity, stars : coronae, stars : individual (HR 1817), radio continuum : stars, techniques : miscellaneous, techniques : Zeeman Doppler imaging
Kaynak
Publications of The Astronomical Society of Australia
WoS Q Değeri
Q3
Scopus Q Değeri
Q1
Cilt
19
Sayı
4
