J/A+A/591/A84 Search for UMa group companions (Ammler-von Eiff+, 2016)
Coronagraphic search for wide substellar companions among members of
the Ursa Major moving group.
Ammler-von Eiff M., Bedalov A., Kranhold C., Mugrauer M., Schmidt T.O.B.,
Neuhaeuser R., Errmann R.
<Astron. Astrophys. 591, A84 (2016)>
=2016A&A...591A..84A 2016A&A...591A..84A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, double and multiple ; Positional data ;
Photometry
Keywords: binaries: visual - stars: imaging - brown dwarfs -
open clusters and associations: individual: Ursae Major -
solar neighborhood
Abstract:
We present the results of a survey to detect low-mass companions of
Ursa Major (UMa) group members, carried out in 2003-2006 with NACO at
the ESO VLT. While many extra-solar planets and planetary candidates
have been found in close orbits around stars by the radial velocity
and the transit methods, direct detections at wider orbits are rare.
The UMa group, a young nearby stellar association at an age of about
200-600Myr, has not yet been addressed as a whole although its members
represent a very interesting sample to search for and characterize
substellar companions by direct imaging.
Our goal was to find or to provide detection limits on wide substellar
companions around nearby UMa group members using high-resolution
imaging.
We searched for faint companions around 20 UMa group members within
30pc. The primaries were placed below a semi-transparent coronagraph,
a rarely used mode of NACO, to increase the dynamic range of the
images. In most cases, second epoch images of companion candidates
were taken to check whether they share common proper motion with the
primary.
Description:
The astrometric and photometric data of companion candidates of
members of the Ursa Major (UMa) group are presented. They were
identified by coronagraphic observations obtained with the S27 camera
of NACO at the ESO VLT, Chile, in 2003-2006. Most of the candidates
were observed a second time to assess whether they share the proper
motion of the star. For this purpose, the change in position with
respect to the star was compared to the stellar parallactic and proper
motion known from Hipparcos. This way, all candidates with two epochs
of observations were rejected being distant background objects. The
layout of the included table deviates from the article version to
facilitate automatic reading, i.e. the epoch date and the primary name
are added to each row, and the candidate identifier is added to the
corresponding data set for each epoch.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 70 11 Basic stellar data of the stars in table D1
(from table A2 of the article)
tabled1.dat 128 214 Astrometry and photometry of candidates
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See also:
J/AJ/105/226 : UMa Group (Soderblom+ 1993)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Star name
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 22 F5.2 s RAs Right ascension (J2000)
24 A1 --- DE- Declination sign (J2000)
25- 26 I2 deg DEd Declination (J2000)
28- 29 I2 arcmin DEm Declination (J2000)
31- 34 F4.1 arcsec DEs Declination (J2000)
36- 41 F6.2 mas plx Parallax (from Hipparcos, van Leeuwen, 2007,
Cat. I/311)
43- 46 F4.2 mas e_plx rms uncertainty on plx
48- 56 A9 --- SpType MK spectral type (1)
58 A1 --- r_SpType [bcd] Reference for SpType (2)
60- 64 F5.3 mag Vmag V magnitude
66- 70 F5.3 mag Ksmag 2MASS Ks magnitude (Skrutskie et al., 2006,
Cat. VII/233)
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Note (1): For spectroscopic binaries, the spectral type is displayed for
both components.
Note (2): Reference for SpType as follows:
b = HD 147584: mean value of M4 of the range given by Skuljan et al.
(2004MNRAS.352..975S 2004MNRAS.352..975S) (M1V-M7V)
c = HD 175742: SB1 (Tokovinin et al., 2006, Cat. J/A+A/450/681);
literature not unanimous on the parameters (Eggleton & Tokovinin, 2008,
Cat. J/MNRAS/389/869)
d = HIP 104383: Balega et al. (2004, Cat. J/A+A/422/627)
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Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Name of stellar target (HD or HIP ID)
12- 21 A10 "date" Epoch1 Date of 1st epoch observation (1)
23- 28 A6 --- IDSeq1 Sequential ID of companion candidates
in 1st epoch (IDNNNN)
30- 36 F7.3 arcsec SepRA1 ? 1st epoch RA separation from central star
38- 42 F5.3 arcsec e_SepRA1 ? Error bar of SepRA1
44- 49 F6.3 arcsec SepDE1 ? 1st epoch DE separation from central star
51- 55 F5.3 arcsec e_SepDE1 ? Error bar of SepDE1
57- 66 A10 "date" Epoch2 ? Date of 2nd epoch observation (1)
68- 73 A6 --- IDSeq2 Sequential ID of companion candidates in
in 2nd epoch (IDNNNN) (2)
75- 81 F7.3 arcsec SepRA2 ? 2nd epoch RA separation from central star
83- 87 F5.3 arcsec e_SepRA2 ? Error bar of SepRA2
89- 94 F6.3 arcsec SepDE2 ? 2nd epoch DE separation from central star
96-100 F5.3 arcsec e_SepDE2 ? Error bar of SepDE2
102-105 F4.1 mag Ksmag ? Ks band magnitude of candidate (3)
107-109 F3.1 mag e_Ksmag ? Error bar of Ks band magnitude
111-114 I4 mas oSepRA ? Offset between epochs in (RA) (4)
116-118 I3 mas e_oSepRA ? Error bar of oSepRA
120-123 I4 mas oSepDE ? Offset between epochs (DE) (4)
125-127 I3 mas e_oSepDE ? Error bar of oSepDE
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Note (1): In several cases, observations from different nights were added up to
obtain a single image with an average date. See Table E.1 in the article.
Note (2): The identifier in the 2nd epoch is identical to the one given in the
1st epoch if it is the same candidate.
Note (3): Notes to the photometric measurement of candidates are not included
in this version of the Table D.1.
Note (4): Difference in the position of a candidate with respect to the star,
i.e. SepRA2-SepRA1 and SepDE2-SepDE1, respectively. The nature of the
candidate, i.e. whether it is a background object or a co-moving companion,
can be assessed by a comparison of these columns to Table E.2 in the article.
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Acknowledgements:
Matthias Ammler-von Eiff, ammler(at)mps.mpg.de
(End) M. Ammler-von Eiff [MPS Goettingen], P. Vannier [CDS] 16-Mar-2016