J/A+A/546/A92 Spectra of HD 120678 (Gamen+, 2012)
The discovery of a shell-like event in the O-type star HD 120678.
Gamen R., Arias J.I., Barba R.H., Morrell N.I., Walborn N.R., Sota A.,
Maiz Apellaniz J., Alfaro E.J.
<Astron. Astrophys., 546, A92-92 (2012)>
=2012A&A...546A..92G 2012A&A...546A..92G
ADC_Keywords: Binaries, spectroscopic ; Spectroscopy ; Radial velocities
Keywords: binaries: spectroscopic - stars: early-type -
stars: emission-line, Be - stars: individual: HD 120678
Abstract:
We report the detection of a shell-like event in the Oe-type star HD
120678.
HD 120678 has been intensively observed as part of a high-resolution
spectroscopic monitoring program of southern Galactic O stars and
Wolf-Rayet stars of the nitrogen sequence.
An optical spectrogram of HD 120678 obtained in June 2008 shows strong
H and HeI absorption lines instead of the double-peaked emission
profiles observed both previously and subsequently, as well as a
variety of previously undetected absorption features, mainly of OII,
SiIII and FeIII. Photometric data reveal that the development of the
absorption spectrum coincided with a remarkable dip in the V-band
lightcurve. The "shell phase" of HD 120678 did not persist for very
long: the V magnitude recovered its previous average value in fewer
than 120 days, whereas H and He emission lines became detectable one
year later. Similar spectral variations have been observed in a few Be
stars, and they are usually interpreted as changes in the
circumstellar disk.
Description:
We observed the spectrum of HD 120678 from the Complejo Astronomico
El Leoncito (CASLEO) in Argentina, as well as from the La Silla (ESO)
and Las Campanas (LCO) Observatories in Chile, during several nights
between May 2006 and September 2011. Most of the observations were
obtained with the echelle spectrographs attached to the 2m class
telescopes of these observatories. Three additional spectrograms were
taken with the MIKE spectrograph at the 6.5m LCO/Magellan II (Clay)
telescope. Two more spectrograms were obtained with the Boller &
Chivens (B&C) spectrograph attached to the 2.5m LCO/du Pont telescope
in the context of the GOSSS project.
The 10 spectra are shown in the Figure 1.
Objects:
----------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------
13 52 56.41 -62 43 14.3 HD 120678 = CD-62 784
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 31 30 Radial velocities of some lines measured in the
spectra of HD 120678
spectra.dat 19 10 List of spectra (wavelength range: 446/470nm)
sp/* . 10 Individual spectra as FITS files
--------------------------------------------------------------------------------
Byte-by-byte Description of file: spectra.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "YYYY-MM-DD" ObsDate Observation date
12- 19 A8 --- FileName Name of the FITS file with spectrum,
in subdirectory sp
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.3 d HJD Heliocentric Julian date (HJD-2450000)
10- 14 F5.1 km/s V5411 ? Radial velocity of HeII5411 absorption line
16- 20 F5.1 km/s V4686 ? Radial velocity of HeII4686 absorption line
22- 26 F5.1 km/s V5875b ? Radial velocity of the violet component of
the HeI5875 emission line
28- 31 F4.1 km/s V5875r ? Radial velocity of the red component of the
HeI5875 emission emission line
--------------------------------------------------------------------------------
Acknowledgements:
Roberto Gamen, rgamen(at)fcaglp.unlp.edu.ar
(End) Patricia Vannier [CDS] 18-Jan-2013