J/AJ/156/174 Visual photometry for the Be star µ Centauri (Aguayo+, 2018)
Multi-epoch L-band spectroscopy of the Be star µ Centauri prior to outburst.
Aguayo G., Mennickent R.E., Granada A., Otero S.
<Astron. J., 156, 174 (2018)>
=2018AJ....156..174A 2018AJ....156..174A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Be ; Photometry ; Optical
Keywords: circumstellar matter - infrared: stars - stars: emission-line, Be -
stars: mass-loss
Abstract:
With the aim of contributing to the understanding of the disk formation
process in Be stars, we pursued a one-year spectroscopic observing
campaign of the Be star µ Centauri in the L-band, using VLT/ISAAC.
We present the nine near-IR spectra we obtained in an epoch of relative
photometric quiescence prior to an outburst of ΔV=0.4 magnitude.
Visual estimates during the epoch of our L-band spectroscopy are also
presented for the first time, together with the unpublished complete
visual light curve between the years 1998 and 2014. We observe significant
and monotonic changes in emission line strength of Bracket-α and
Pfund-γ lines relative to Humphreys lines, and also in the continuum
slope. We interpret these observed changes in terms of important changes
to the column density of the line emitting regions, moving from an
optically thin to an optically thick stage just prior to a major outburst.
For each observing date, we provide estimates for the column density and
relative extension of the line emitting region. If the changes observed
toward the end of our observing campaign were related to mass-loss changes
from the central star, they would correspond to an increase in a factor
of two in the mass of the disk in the innermost region. If related to
the visual outburst observed one month later, the variability observed
in our spectra would be the first detection of the early disk formation
process in the L-band.
Description:
Visual photometry was performed by Sebastian Otero from Buenos Aires,
Argentina using the Argelander method (Argelander 1843,
1843nus..book.....A 1843nus..book.....A) which consists in the observation of a target star
and non-variable stars as comparison stars with magnitudes and colors
as similar as possible to the variable star. This observational method
has been recently validated for bright variable stars (Carciofi et al.
2012ApJ...744L..15C 2012ApJ...744L..15C; Chesneau et al. 2014A&A...563A..71C 2014A&A...563A..71C; Stefl et al.
2003A&A...402..253S 2003A&A...402..253S) and results compared with photoelectric photometry
with a resulting accuracy of 0.05 mag or better for bright naked eye
stars like µ Centauri (Otero, Fraser & Lloyd 2001IBVS.5026....1O 2001IBVS.5026....1O;
Otero & Moon 2006JAVSO..34..156O 2006JAVSO..34..156O).
Objects:
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RA (ICRS) DE Designation(s)
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13 49 36.99 -42 28 25.4 µ Centauri = * mu. Cen
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table8.dat 21 905 Visual photometry for µ Centauri
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See also:
J/A+AS/129/289 : Long-term spectrophotometry of Be stars (Moujtahid+ 1998)
J/ApJ/652/458 : BVRHα photometry of candidates Be stars
(Wisniewski+, 2006)
J/MNRAS/463/1162 : Infrared photometry of Be stars (Chen+, 2016)
J/AJ/155/53 : Outbursts and disk variability in Be stars
(Labadie-Bartz+, 2018)
Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 10 F10.4 d MJD Modified Julian Date (JD-2400000.5)
12- 16 F5.3 mag Vmag [3.078/3.566] Visual magnitude
18- 21 F4.2 mag e_Vmag [0.03/0.15] Uncertainty in Vmag
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 19-Mar-2019