J/ApJ/671/2040 Polarisation of candidates Be stars (Wisniewski+, 2007)
The role of evolutionary age and metallicity in the formation of classical Be
circumstellar disks.
II. Assessing the evolutionary nature of candidate disk systems.
Wisniewski J.P., Bjorkman K.S., Magalhaes A.M., Bjorkman J.E., Meade M.R.,
Pereyra A.
<Astrophys. J., 671, 2040-2058 (2007)>
=2007ApJ...671.2040W 2007ApJ...671.2040W
ADC_Keywords: Magellanic Clouds ; Stars, Be ; Polarization
Keywords: circumstellar matter - galaxies: clusters: individual (Bruck 60,
NGC 330, NGC 346, NGC 371, NGC 456, NGC 458, LH 72, NGC 1818,
NGC 1858, NGC 1948, NGC 2004, NGC 2100) - Magellanic Clouds -
stars: emission-line, Be - techniques: polarimetric -
stars: individual (pi Aquarii, BD +61 154, MWC 349A)
Abstract:
We present the first detailed imaging polarization observations of six
SMC and six LMC clusters, known to have large populations of B-type
stars that exhibit excess Hα emission from 2-CD photometric
studies, to constrain the evolutionary status of these stars and hence
better establish links between the onset of disk formation in
classical Be stars and cluster age and/or metallicity. We parameterize
and remove the interstellar polarization (ISP) associated with each
line of sight, thereby isolating the presence of any intrinsic
polarization. We use the wavelength dependence of this intrinsic
polarization to discriminate pure gas disk systems, i.e., classical Be
stars, from composite gas-plus-dust disk systems, i.e., Herbig Ae/Be
or B[e] stars.
Description:
The imaging polarimetry data presented in this study were obtained
with the Cerro Tololo Inter-American Observatory (CTIO)7 1.5m
telescope. between 2001 Oct 17 and 2001 Nov 27.
Objects:
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RA (2000) DE Designation(s)
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00 51 41.7 -73 13 47 Bruck 60 = DEM S 60
05 32 12. -66 27 LH 72 = LH 72
00 56 18.7 -72 27 50 NGC 330 = Cl Kron 35
00 59 18. -72 10 48 NGC 346 = Cl Kron 39
01 03 25. -72 04 24 NGC 371 = Cl Kron 48
01 13 50. -73 18 00 NGC 456 = Cl Kron 65
01 14 53.4 -71 32 59 NGC 458 = Cl Kron 69
05 04 13.8 -66 26 02 NGC 1818 = KMHK 491
05 09 56.1 -68 54 06 NGC 1858 = LH 31
05 24 20.0 -66 24 12 NGC 1948 = DEM L 175a
05 30 40.2 -67 17 14 NGC 2004 = KMHK 991
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 53 1792 Total polarization of candidate Be stars
table7.dat 53 1792 Intrinsic polarization of candidate Be stars
table8.dat 67 369 Classifying the intrinsic polarization of
individual candidate Be stars
table13.dat 56 120 IR colors of candidate Be stars
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See also:
J/A+AS/119/271 : Be stars uvbyβ photometry (Fabregat+, 1996)
J/A+AS/125/75 : UBV photometry of Be stars (Pavlovski+ 1997)
J/A+AS/129/289 : Long-term spectrophotometry of Be stars (Moujtahid+ 1998)
J/A+AS/134/489 : Be stars in MC young clusters (Keller+ 1999)
J/A+A/317/448 : BVRHalpha photometry of NGC 1818 (Grebel 1997)
J/A+A/376/144 : BV(RI)CHα photometry of NGC 663 (Pigulski+, 2001)
J/other/NewA/9.509 : IRAS observations of Be stars (Zhang+, 2004)
J/other/NewA/10.325 : 2MASS observations of Be stars (Zhang+, 2005)
J/MNRAS/361/1055 : BVI photometry of LMC Be stars (Sabogal+, 2005)
J/ApJ/622/1052 : byHα photometry of NGC 3766 (McSwain+, 2005)
J/A+A/462/683 : Velocities in SMC field of NGC 330 (Martayan+, 2007)
J/A+A/472/577 : NGC 330 Be stars and binaries (Martayan+, 2007)
J/A+A/478/659 : OGLE Be stars in Galactic Bulge (Sabogal+, 2008)
J/ApJ/652/458 : Candidates Be stars BVRHa photometry (Wisniewski+, 2006)
Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- ID Candidate Be star identification
21 A1 --- Filt [ubvri] Filter used in the observation
23- 27 F5.2 % Polt ? Total polarization (1)
29- 34 F6.2 deg polPAt ? Position angle of total polarization
36- 41 F6.3 % Qt ? Stokes Q polarization
43- 47 F5.2 % Ut ? Stokes U polarization
49- 53 F5.2 % e_Polt ? Polarization error
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Note (1): Interstellar plus intrinsic components.
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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- 19 A19 --- ID Candidate Be star identification
21 A1 --- Filt [ubvri] Filter used in the observation
23- 27 F5.2 % Poli ? Intrinsic polarization
29- 34 F6.2 deg polPAi ? Position angle of intrinsic polarization
35- 40 F6.2 % Qi ? Stokes Q polarization
42- 46 F5.2 % Ui ? Stokes U polarization
49- 53 F5.2 % e_Poli ? Polarization error
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- ID Candidate Be star identification
21- 22 A2 --- Jump Polarization Balmer jump present?
24- 27 A4 --- PAdes Polarization position angle description (1)
29- 31 F3.1 --- Class Be star classification (2)
33- 67 A35 --- Comm Additional comments
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Note (1): Position angle was flat (F), linearly sloped (S), or randomly
variable (V) while the numbers indicate the σ level of such
characterizations.
Note (2): The likelihood each object is a bona-fide classical Be star based
on the 4 point classification scheme described in the text.
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Byte-by-byte Description of file: table13.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- ID Candidate Be star identification (1)
21- 34 A14 --- Class Polarimetric designation (2)
36- 40 F5.2 mag J-H 2MASS (J-H) color index
42- 46 F5.2 mag H-K 2MASS (H-K) color index
48- 51 F4.2 mag e_J-H Error in J-H (3)
53- 56 F4.2 mag e_H-K Error in H-K (3)
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Note (1): Near-IR colors are tabulated for all candidate Be stars in
clusters investigated in this paper which were detected in all three
2MASS photometric bands.
Note (2): Polarimetric designation as follows:
Type-1:Bal-J = Type-1 sources which we assert are most likely to be
classical Be stars
Type-2:ES = Type-2 sources which exhibit electron scattering
intrinsic polarimetric signatures and are thus
likely classical Be stars
Type-2-4,other = All other sources, regardless of whether they were
detected via our polarimetric survey or not
Note (3): Obtained by adding individual filter errors in quadrature.
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History:
From electronic version of the journal
References:
Wisniewski & Bjorkman, Paper II, 2006ApJ...652..458W 2006ApJ...652..458W (Cat. J/ApJ/652/458)
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 10-Nov-2009