J/PASP/106/949 Multicolor polarimetry of Be stars (McDavid, 1994)
Multicolor polarimetry of selected Be stars: 1990-93
McDavid D.
<Publ. Astron. Soc. Pac. 106, 949 (1994)>
=1994PASP..106..949M 1994PASP..106..949M (SIMBAD/NED Reference)
ADC_Keywords: Stars, Be ; Photometry, UBVRI ; Polarization
Abstract:
Optical polarization data in the UBVRI filter system for eight bright
northern Be stars are presented here as the continuation of a
long-term monitoring project begun in 1984. There are no strong cases
of night-to-night variability, and the only star showing unmistakable
changes in polarization from year to year over the nine years covered
by the program is Pi Aquarii. Even though the observed sample spans a
wide range in spectral type, vsini, and degree of intrinsic
polarization, the normalized wavelength dependence of the polarization
is surprisingly similar for all of the stars. Analysis of the
wavelength dependence of the variable polarization of π Aqr in terms
of a simple equatorial-disk model suggests that changes in the
circumstellar electron number density alone may be sufficient to
account for the observations, but it is not clear what real physical
mechanism is involved.
Addresses:
McDavid D.
Limber Observatory, Timber Creek Road, P.O. Box 63599,
Pipe Creek,Texas 78063
Explanatory Note:
Tables 3-12 include data from two previous publications:
McDavid, D. 1986PASP...98..572M 1986PASP...98..572M and McDavid, D. 1990PASP..102..773M 1990PASP..102..773M.
Objects:
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RA (2000) DE Designation(s)
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03 29 04.1 +59 56 25 2H Cam = HD 21291
16 20 38.1 -24 10 08 omicron Sco = HD 147084
00 56 42.2 +60 43 01 gamma Cas = HD 5394
01 43 39.4 +50 41 20 phi Per = HD 10516
04 08 39.5 +47 42 47 48 Per = HD 25940
05 37 38.6 +21 08 34 zeta Tau = HD 37202
15 58 11.3 -14 16 45 48 Lib = HD 142983
16 27 01.3 -18 27 21 chi Oph = HD 148184
22 25 16.5 +01 22 38 pi Aqr = HD 212571
23 01 55.1 +42 19 34 omicron And = HD 217675
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 44 8 Program Be stars
table2 11 5 Filter system parameters
table3 62 40 Polarization of 2H Cam (standard star)
table4 62 40 Polarization of ο Sco (standard star)
table5 62 40 Polarization of γ Cas
table6 62 45 Polarization of φ Per
table7 62 45 Polarization of 48 Per
table8 62 45 Polarization of ζ Tau
table9 62 45 Polarization of 48 Lib
table10 62 45 Polarization of χ Oph
table11 62 45 Polarization of π Aqr
table12 62 40 Polarization of ο And
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Star name
9- 14 I6 --- HD HD (Cat. III/135) catalog number
16- 19 I4 --- HR BS (Cat. V/50) catalog number
21- 24 F4.2 mag Vmag Visual magnitude (BSC4, See Cat. V/50)
26- 40 A15 --- Sp Spectral type (1)
42- 44 I3 km/s vsini vsini (1)
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Note (1): According to Slettebak, A. 1982ApJS...50...55S 1982ApJS...50...55S
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Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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1 A1 --- Passband Filter system passband
3- 6 I4 0.1nm Wavelength Effective wavelength
8- 11 I4 0.1nm FWHM Bandpass
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Byte-by-byte Description of file: table3 table4 table5 table6 table7 table8
Byte-by-byte Description of file: table9 table10 table11 table12
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Bytes Format Units Label Explanations
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1- 2 I2 --- Month Month of observations
4- 5 I2 yr Year-1900 Year (offset 1900) of observation
7 A1 --- Passband [UBVRI] Filter system passband
9- 10 I2 --- nobs []? Number of observations
12- 16 F5.2 % q []? Mean normalized Stokes parameter q
18- 21 F4.2 % e_q []? rms uncertainty on q
23- 27 F5.2 % u []? Mean normalized Stokes parameter u
29- 32 F4.2 % e_u []? rms uncertainty on u
34- 37 F4.2 % p Mean degree of polarization
39- 42 F4.2 % e_p []? rms uncertainty on p
44- 48 F5.1 deg theta Mean equatorial position angle
50- 53 F4.1 deg e_theta []? rms uncertainty on theta
55- 58 F4.2 % dpi []? Instrumental precision of q, u, or p (1)
60- 62 F3.1 deg dthetai []? Instrumental precision of theta (2)
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Note (1): dpi = mean instrumental error in the degree of polarization for each
set of measurements according to photon statistics, unless photon
statistics gives a value less than 0.02%, in which case the error is
approximated as 0.02% due to atmospheric scintillation for the
200-second integration time
Note (2): dthetai = mean instrumental error in equatorial position angle of the
polarization, based on the relation dthetai=28.65(dpi/p)
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Origin: AAS CD-ROM series, Volume 3, 1995
(End) David McDavid [Limber Obs.] 12-Sep-1994, Patricia Bauer [CDS] 16-Feb-1995