dc.contributor.author |
Bhat, S. S |
|
dc.contributor.author |
Paul, K. T |
|
dc.contributor.author |
Subramaniam, A |
|
dc.contributor.author |
Mathew, B |
|
dc.date.accessioned |
2020-11-19T13:37:02Z |
|
dc.date.available |
2020-11-19T13:37:02Z |
|
dc.date.issued |
2016-06 |
|
dc.identifier.citation |
Research in Astronomy and Astrophysics, Vol. 16, No. 05, pp. 76 |
en_US |
dc.identifier.issn |
1674-4527 |
|
dc.identifier.uri |
http://prints.iiap.res.in/handle/2248/7242 |
|
dc.description |
Restricted Access © IOP Publishing http://dx.doi.org/10.1088/1674-4527/16/5/076 |
en_US |
dc.description.abstract |
We present an optical spectroscopic study based on 41 spectr
a of 4 Her and 32 spectra of 88 Her,
obtained over a period of 6 months. We estimate the rotationa
l velocity of these stars from He
I
lines in the
blue spectral region (4000–4500
̊
A). We find that these stars are likely to be rotating at a fract
ional critical
rotation of
∼
0.80. We measure the average
I
p
/I
c
ratio to quantify the strength of the H
α
line and obtain
1.63 for 4 Her and 2.06 for 88 Her. The radius of the H
α
emission region is estimated to be
R
d
/R
∗
∼
5.0,
assuming a Keplerian disk. These stars are thus found to be fa
st rotators with a relatively small H
α
emission
region. We detect
V/R
variation of the H
α
spectral line during the observed period. We re-estimate th
e
periods for both stars and obtain a period of
∼
46 d and its harmonic of 23.095 d for 4 Her, and a period of
∼
86 d for 88 Her. As these two cases are shell stars with binarie
s and have low H
α
EW with the emission
region closer to the central star, the
V/R
variation and a change in period may be an effect of the binary
on
the circumstellar disk. |
en_US |
dc.language.iso |
en |
en_US |
dc.publisher |
IOP Publishing |
en_US |
dc.subject |
Stars: emission-line, Be |
en_US |
dc.subject |
Circumstellar matter |
en_US |
dc.subject |
Stars: individual (4 Her, 88 Her) |
en_US |
dc.subject |
Stars: rotation |
en_US |
dc.subject |
Techniques: spectroscopic |
en_US |
dc.title |
Spectroscopic study of Be-shell stars : 4 Her and 88 Her |
en_US |
dc.type |
Article |
en_US |