J/A+A/459/669 JHKs photometry around α Cen (Kervella+, 2006)
Deep imaging survey of the environment of α Centauri.
I. Adaptive optics imaging of α Cen B with VLT-NACO.
Kervella P., Thevenin F., Coude Du Foresto V., Mignard F.
<Astron. Astrophys., 459, 669-678 (2006)>
=2006A&A...459..669K 2006A&A...459..669K
ADC_Keywords: Stars, double and multiple ; Photometry, infrared
Keywords: techniques: high angular resolution - stars: individual: alpha Cen -
stars: planetary systems - stars: solar neighbourhood -
astronomical data bases: miscellaneous - infrared: stars
Abstract:
alpha Centauri is our closest stellar neighbor, at a distance of only
1.3pc, and its two main components have spectral types comparable to
the Sun. This is therefore a favorable target for an imaging search
for extrasolar planets. Moreover, indications exist that the
gravitational mass of alpha Cen B is higher than its modeled mass,
the difference being consistent with a substellar companion of a few
tens of Jupiter masses.
We searched for faint comoving companions to alpha Cen B. As a
secondary objective, we built a catalogue of the detected background
sources.
We used the NACO adaptive optics system of the VLT in the J, H, and Ks
bands to search for companions to alpha Cen B. This instrument allowed
us to achieve a very high sensitivity to point-like sources, with a
limiting magnitude of m_Ks∼18 at 7" from the star. We complemented
this data set with archival coronagraphic images from the HST-ACS
instrument to obtain an accurate astrometric calibration.
Description:
We thus observed the environment of alpha Cen B using the Nasmyth
Adaptive Optics System (NAOS) of the Very Large Telescope (VLT),
coupled to the CONICA infrared camera. The combination of these two
devices is abbreviated as NACO. The first series of observations were
obtained between February 18 and April 10, 2004.
We repeated the same observations one year later in order to identify
the proper-motion companions, using the Ks filter only because all
the sources identified in the J and H bands were also detected in Ks.
One image of the southern field was obtained in July 2004, but due to
operational constraints, the remaining observations were conducted in
February-March 2005.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table7.dat 56 252 Position and photometry of the sources detected
around α Cen
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [KTC2006] Sequential number
5- 6 I2 h RAh Right ascension (ICRS, Ep=J2004.5)
8- 9 I2 min RAm Right ascension (ICRS, Ep=J2004.5)
11- 16 F6.3 s RAs Right ascension (ICRS, Ep=J2004.5)
18 A1 --- DE- Declination sign (ICRS, Ep=J2004.5)
19- 20 I2 deg DEd Declination (ICRS, Ep=J2004.5)
22- 23 I2 arcmin DEm Declination (ICRS, Ep=J2004.5)
25- 29 F5.2 arcsec DEs Declination (ICRS, Ep=J2004.5)
31- 34 F4.1 mag Jmag ? J magnitude
36- 38 F3.1 mag e_Jmag ? rms uncertainty on Jmag
40- 43 F4.1 mag Hmag ? H magnitude
45- 47 F3.1 mag e_Hmag ? rms uncertainty on Hmag
49- 52 F4.1 mag Ksmag ? Ks magnitude
54- 56 F3.1 mag e_Ksmag ? rms uncertainty on Ksmag
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 11-May-2007