J/A+A/493/931 MAD observations of σ Ori (Bouy+, 2009)
A deep look into the cores of young clusters. I. σ-Orionis.
Bouy H., Huelamo N., Martin E.L., Marchis F., Barrado Y Navascues D.,
Kolb J., Marchetti E., Petr-Gotzens M.G., Sterzik M., Ivanov V.D.,
Koehler R., Nuernberger D.
<Astron. Astrophys., 493, 931-946 (2009)>
=2009A&A...493..931B 2009A&A...493..931B
ADC_Keywords: Associations, stellar; Stars, nearby ; Photometry, infrared
Keywords: stars: formation - stars: low-mass, brown dwarfs -
stars: planetary system - techniques: high angular resolution -
stars: early-type
Abstract:
Nearby young clusters are privileged places to study the star
formation history. Over the last decade, the sigma-Orionis cluster
has been a prime location for the study of young very low mass stars,
substellar and isolated planetary mass objects and the determination
of the initial mass function.
To extend previous studies of this association to its core, we
searched for ultracool members and new multiple systems within the
1.5'x1.5' central region of the cluster.
We obtained deep multi-conjugate adaptive optics (MCAO) images of the
core of the sigma-Orionis cluster with the prototype MCAO facility MAD
at the VLT using the H and Ks filters. These images allow us to detect
companions fainter by DeltaH∼5mag as close as 0.2" on a typical source
with H=14.5mag. These images were complemented by archival SofI
Ks-band images and Spitzer IRAC and MIPS mid-infrared images.
Description:
MAD is a prototype instrument performing wide field-of-view, real-time
correction for atmospheric turbulence.
MAD was built by the European Southern Observatory (ESO) with the
contribution of two external consortia to prove the feasibility of
MCAO on the sky in the framework of the 2nd generation VLT
instrumentation and of the European Extremely Large Telescope.
During the on-sky demonstration run of MAD held in November 2007, a
region of 1.5'x1.5' centered on the sigma-Orionis cluster was
observed in the H and Ks filters.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 111 36 Catalog of sources detected in the MAD images
table8.dat 69 398 NTT/SofI Ks-band photometry
--------------------------------------------------------------------------------
See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/478/667 : The Mayrit catalogue (Caballero, 2008)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_MAD [*+] PMO/BD object (1)
2- 12 A11 --- --- [SigOri-MAD]
13- 14 I2 --- MAD SigOri-MAD number (SigOri-MAD-NN)
16- 17 I2 h RAh Right ascension (J2000)
19- 20 I2 min RAm Right ascension (J2000)
22- 25 F4.1 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 37 F4.1 arcsec DEs Declination (J2000)
39- 43 F5.2 mag Hmag ? H magnitude
45- 48 F4.2 mag e_Hmag ? rms uncertainty on Hmag (2)
50 A1 --- l_Ksmag Limit flag on Ksmag
51- 55 F5.2 mag Ksmag Ks magnitude
57- 60 F4.2 mag e_Ksmag ? rms uncertainty on Ksmag (2)
62- 88 A27 --- OName Other name
90-111 A22 --- Com Comments
--------------------------------------------------------------------------------
Note (1): Note as follows:
* = objects with H-band luminosity corresponding to a
Planetary-Mass Object (PMO), defined here as M≤0.012M☉
+ = objects with H-band luminosity corresponding to a
Brown Dwarf (BD), defined here as 0.012<M≤0.072M☉)
Note (2): The errors include the zeropoint uncertainties.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- --- [SigOri-SofI]
13- 15 I3 --- SofI SigOri-SofI number (SigOri-SofI-NNN)
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 26 F4.1 s RAs Right ascension (J2000)
28 A1 --- DE- Declination sign (J2000)
29- 30 I2 deg DEd Declination (J2000)
32- 33 I2 arcmin DEm Declination (J2000)
35- 38 F4.1 arcsec DEs Declination (J2000)
40- 44 F5.2 mag Ksmag Ks magnitude (1)
46- 61 A16 --- 2MASS Nearest 2MASS source name (2)
64- 69 I6 --- Mayrit ? Nearest Mayrit source name (2)
--------------------------------------------------------------------------------
Note (1): The error on the photometry is dominated by the zeropoint
uncertainty (0.19mag).
Note (2): The 2MASS and Mayrit 2008, Cat. J/A+A/478/667 nearest matches
within 5" are indicated. Because of the higher spatial resolution of
the SofI image compared to these two catalogs, the same 2MASS or
Mayrit source is sometimes associated to several SofI sources.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Mar-2009