Open AccessThe 1998 decline of V854 Centauri
Author(s) -
Skuljan Lj.,
Cottrell P. L.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05689.x
Subject(s) - physics , astrophysics , blueshift , redshift , photometry (optics) , emission spectrum , line (geometry) , astronomy , spectral line , galaxy , stars , geometry , mathematics , optics , photoluminescence
Abstarct Photometry and low‐ to high‐resolution spectroscopy have been obtained throughout the 1998 decline of V854 Centauri. This is the most complete coverage of a decline of this star. Various emission lines which are typical of an RCB decline have been observed. Their evolution is consistent with the classification into three groups according to the E 1 /E 2 /BL line‐region model. However, some of the line characteristics indicate a different origin from that suggested by the model. The low‐excitation sharp emission lines (E 2 group), visible throughout the whole decline, show a blueshift of about 3 km s −1 and a complex profile indicating a shell with its outer region expanding faster than the inner parts. The estimated position of this region is at about 3.5 R * , assuming the dust cloud condensation occurs at about 2 R * . The high‐excitation lines of C i , O i and Mg i , classified as E 1 , exhibit a redshift of a few km s −1 relative to the stellar velocity, indicating a possible photospheric origin. The broad lines (BL group) show a constant absolute flux throughout the decline phase and therefore the region of their origin does not seem to be affected or obscured by the dust cloud causing the decline. The high‐velocity Na i D absorption components, at a velocity of about −400 km s −1 , show a constantly increasing blueshift interpreted as an acceleration of the gas associated with the dust cloud formation.