Observations of the 44 Be stars presented here, were carried out
between April 1998 and January 2000 on the 1.2 m. Cassegrain
telescope of the Mount Abu Infrared Observatory, India. All the
observations were made using a fibre linked astronomical grating
spectrograph (FLAGS), recently made operational (Banerjee et al.
1999). The spectrograph has a Czerny Turner configuration with f/10optics of 1.5 m focal length. It is mounted on a bench and light
from the f/13 Cassegrain focal plane of the telescope is fed into it
by means of an optical fibre (fibre type FIP 320385415, manufactured
by Polymicro Technologies, U.S.A.). The dispersing element is a 2400
lines/mm Jobin Yvon holographic grating used in first order. It gives a
reciprocal dispersion of 0.135 Å pixel at the detector and a
spectral coverage of about 25 Å per CCD frame.
The resolving power of the spectrograph, constrained
primarily by the 320 micron diameter of
the core of the
optical fibre, is approximately 13000 at the
H
wavelength. We have used a CCD with a Kodak KAF 1600 grade 1
chip as the detector. The main limitation of the detector is that it
is only thermo-electrically cooled and does not generally permit cooling
below
C. Incidentally, we are trying to acquire a liquid nitrogen
cooled CCD for the spectrograph with which we plan to continue the
Be star programme.
All our spectra have been obtained at
C. Consequently the dark
count level has been just sufficient to given moderate S/N ratios in our
spectra vis-a-vis those obtained by some other observers like for example
Hanuschik et al. (1996). Nevertheless, our data compares
reasonably well
with earlier studies of Dachs et al. (1986), and Andrillat &
Fehrenbach (1982), and should supplement the existing data base of
emission line profiles of Be stars, especially in regards to their
temporal variation. Indeed, even at its present performance level,
FLAGS does provide adequate resolving power and S/N ratio to detect
fine structures like wine-bottle inflections in the profiles. As
pointed out by Hanuschik (1996), these structures become
apparent only
when high resolution and S/N profiles are available (Hanuschik 1986,
1987; Hanuschik et al. 1988; Doazan et al. 1991;
Slettebak et al. 1992; Dachs et al. 1992).
HR No. | Name | HD No. | mv | Epoch |
193 | Omi Cas | 4180 | 4.54 | 23.12.98 |
264 | Gamma Cas | 5394 | 2.47 | 23.12.98 |
264 | Gamma Cas | 5394 | 2.47 | 29.11.99 |
335 | Phi And | 5394 | 4.25 | 22.12.98 |
496 | Phi Per | 10516 | 4.07 | 30.1.00 |
1087 | Psi Per | 22192 | 4.23 | 22.12.98 |
1165 | Eta Tau | 23630 | 2.87 | 30.11.99 |
1180 | 28 Tau | 23862 | 5.09 | 30.11.99 |
1273 | 48 Per | 25940 | 4.04 | 23.12.98 |
1508 | 56 Eri | 30076 | 5.9 | 16.3.99 |
1622 | 11 Cam | 32343 | 5.08 | 15.3.99 |
1660 | 105 Tau | 32991 | 5.89 | 15.3.99 |
1789 | 25 Psi Ori | 35439 | 4.95 | 30.1.00 |
1858 | 120 Tau | 36576 | 5.69 | 14.4.99 |
1910 | Zet Tau | 37202 | 3 | 16.3.99 |
1934 | Ome Ori | 37490 | 4.57 | 22.12.98 |
1956 | Alpha Col | 37795 | 2.64 | 13.4.99 |
2284 | FR CMa | 44458 | 5.64 | 19.2.99 |
2343 | Nu Gem | 45542 | 4.15 | 12.4.99 |
2356 | Beta MonA | 45725 | 4.6 | 28.11.98 |
2358 | Beta MonC | 45727 | 5.6 | 28.11.98 |
2492 | 10 CMa | 48917 | 5.2 | 23.12.98 |
2538 | 13 K Cma | 50013 | 3.96 | 15.3.99 |
2749 | 28 Ome Cma | 56139 | 3.85 | 20.2.99 |
2787 | 57150 | 4.69 | 14.4.99 | |
2817 | 58050 | 6.41 | 26.11.98 | |
2825 | 58343 | 5.33 | 20.2.99 | |
2845 | 3 Beta CMi | 58715 | 2.9 | 12.4.99 |
3135 | 65875 | 6.51 | 23.12.98 | |
3237 | MX Pup | 68980 | 4.78 | 13.4.99 |
3858 | 83953 | 4.77 | 19.2.99 | |
3946 | 86612 | 6.21 | 14.4.99 | |
4621 | Del Cen | 105435 | 2.6 | 14.4.99 |
4696 | 5 Crv | 107348 | 5.21 | 14.4.99 |
4787 | 5 KDra | 109387 | 3.87 | 19.2.99 |
5193 | Mu Cen | 120324 | 3.04 | 21.2.99 |
5440 | Eta Cen | 127972 | 2.31 | 21.2.99 |
5778 | 4 The Crb | 138749 | 4.14 | 12.4.99 |
5941 | 48 Lib | 142983 | 4.88 | 15.3.99 |
6118 | Chi Oph | 148184 | 4.42 | 28.4.98 |
6118 | Chi Oph | 148184 | 4.42 | 15.3.99 |
6510 | Alpha Ara | 158427 | 2.95 | 13.4.99 |
6712 | 66 Oph | 164284 | 4.64 | 12.4.99 |
7106 | 10 Beta Lyr | 174638 | 3.45 | 12.4.99 |
7763 | 34 P Cyg | 193237 | 4.81 | 30.11.99 |
8773 | 4 Beta Psc | 217891 | 4.53 | 27.11.98 |
The details of the observations are presented in Table 1.
The table
gives the HR number, the star name, the HD number, the magnitude mvand the epoch of observation for all the stars that have been studied.
Each of the spectra was obtained with an integration time of 10 min.
Calibration of the wavelength scale on the
detector was done using the identified lines of the solar spectrum
(Kurucz et al. 1984). The rest wavelength of the
laboratory H
line was determined
by using a hydrogen spectral lamp. The hydrogen lamp calibration frames
were taken regularly before, in between and after the object frames to
keep a check on the instrument performance and the position of the
H
rest wavelength.
Copyright The European Southern Observatory (ESO)