J/A+A/587/A115 Luminous blue variables NACO and VISIR images (Martayan+, 2016)
Luminous blue variables:
An imaging perspective on their binarity and near environment.
Martayan C., Lobel A., Baade D., Mehner A., Rivinius T., Boffin H.M.J.,
Girard J., Mawet D., Montagnier G., Blomme R., Kervella P., Sana H.,
Stefl S., Zorec J., Lacour S., Le Bouquin J.-B., Martins F., Merand A.,
Patru F., Selman F., Fremat Y.
<Astron. Astrophys. 587, A115 (2016)>
=2016A&A...587A.115M 2016A&A...587A.115M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, blue
Keywords: stars: variables: S Doradus - stars: Wolf-Rayet - stars: imaging -
binaries: general - stars: winds, outflows
Abstract:
Luminous blue variables (LBVs) are rare massive stars with very high
luminosity. They are characterized by strong photometric and
spectroscopic variability related to transient eruptions. The
mechanisms at the origin of these eruptions is not well known. In
addition, their formation is still problematic and the presence of a
companion could help to explain how they form.
This article presents a study of seven LBVs (about 20% of the known
Galactic population), some Wolf-Rayet stars, and massive binaries. We
probe the environments that surround these massive stars with near-,
mid-, and far-infrared images, investigating potential nebula/shells
and the companion stars.
To investigate large spatial scales, we used seeing-limited and near
diffraction-limited adaptive optics images to obtain a differential
diagnostic on the presence of circumstellar matter and to determine
their extent. From those images, we also looked for the presence of
binary companions on a wide orbit. Once a companion was detected, its
gravitational binding to the central star was tested. Tests include
the chance projection probability, the proper motion estimates with
multi-epoch observations, flux ratio, and star separations.
Description:
The stars in our sample were selected for their properties to
investigate the binary nature of LBVs and to study the envelope
structure.
To study the binarity and the environment of the objects, two cameras
with good spatial resolution were used. The first one is NACO with its
adaptive optics facility and the second is VISIR. Both cameras allow
near- to mid-IR observations. Our observations are summarized in
Table 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 46 9 Catalogue of objects surrounding HD168625 in a
radius of 18" as shown in Fig. 1
tableb2.dat 52 238 Catalogue of objects surrounding the Pistol Star
within a box of 14"x14" as defined in Fig. A1-A8
list.dat 162 7 List of fits images
fits/* . 7 Individual fits images
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Table2: Summary of the NACO and VISIR observations.
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Date Inst. Mode Length Seeing Transparency
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17/06 + 01/08/2010 NACO SM 4x1 h 0.8" clear
17-18/07/2011 NACO VM 1. n 0.65-0.8" clear
18-19/07/2011 a NACO VM 0.5 n 0.55-0.65" clear-thin
20/07/2011 b VISIR VM 0.5 n 1.0 -1.5" thin-thick
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Notes. The service mode (SM) or visitor mode (VM) is indicated in Col. 3.
The length of the observations is given in hours or in nights in Col. 4.
Columns 5 and 6 provide the weather condition: R-band image quality and
sky transparency.
Note on Date:
(a) a NACO technical problem prevented observation of the star WR102ka.
(b) a significant fraction of the planned observations were not performed
owing to the weather.
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Star Star name
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 34 F5.2 arcsec DEs Declination (J2000)
36 A1 --- l_Lpmag Limit flag on Lpmag
37- 41 F5.2 mag Lpmag NACO Lp (3.80um) magnitude (1)
43- 46 F4.2 mag e_Lpmag ? rms uncertainty on Lpmag
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Note (1): The NACO Lp magnitude is provided as an indication.
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Byte-by-byte Description of file: tableb2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Star Star name (1)
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 27 F5.2 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 40 F5.2 arcsec DEs Declination (J2000)
42- 46 F5.2 mag Kmag ?=99 NACO K magnitude (2)
47 A1 --- u_Kmag Uncertainty flag on Kmag (1)
49- 52 F4.2 mag e_Kmag ?=9 rms uncertainty on Kmag
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Note (1): Stars with (+) are blended and their magnitude is not accurate
(indicated with :).
Note (2): The NACO K magnitude is provided as an indication. An offset of the
zeropoint may exist (magnitudes may have to be corrected by about +1 mag).
Entries with K mag values of 99 indicate there are no reliable measurements.
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star name
13- 24 A12 --- Class Classification (from table1) (1)
26 A1 --- n_Class [c] c: Classification form Raw et al.
(2012A&A...542A..95R 2012A&A...542A..95R)
28- 36 F9.5 deg RAdeg Right Ascension of center (J2000)
37- 45 F9.5 deg DEdeg Declination of center (J2000)
47- 52 F6.4 arcsec/pix scale Scale of the image
54- 57 I4 --- Nx Number of pixels along X-axis
59- 62 I4 --- Ny Number of pixels along Y-axis
64- 87 A24 --- Obs.Date Observation date
89- 92 I4 Kibyte size Size of FITS file
94-139 A46 --- FileName Name of FITS file, in subdirectory fits
141-162 A22 --- Title Title of the FITS file
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Note (1): Candidate LBV stars are identified with "cLBV".
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Acknowledgements:
Christophe Martayan, cmartaya(at)eso.org
(End) Patricia Vannier [CDS] 02-Mar-2016