CDROM/PASP/V106/P0949
Multicolor Polarimetry of Be Stars (McDavid
1994)
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Multicolor Polarimetry of Selected Be Stars: 1990-93
David McDavid
<1994, PASP, 106, 949>
=1994PASP..106..949M
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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 Pi 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.
Explanatory Note:
Tables 3-12 include data from two previous publications: McDavid, D.
1986,
PASP, 98, 572 and McDavid, D. 1990, PASP, 102, 773.
File Summary:
------------------------------------------------------------------------------File Name
Lrecl
Records
Explanations
------------------------------------------------------------------------------table1.dat
44
8
Program Be stars
table2.dat
11
5
Filter system parameters
table3.dat
62
40
Polarization of 2H Cam (standard star)
table4.dat
62
40
Polarization of Omicron Sco (standard
star)
table5.dat
62
40
Polarization of Gamma Cas
table6.dat
62
45
Polarization of Phi Per
table7.dat
62
45
Polarization of 48 Per
table8.dat
62
45
Polarization of Zeta Tau
table9.dat
62
45
Polarization of 48 Lib
table10.dat
62
45
Polarization of Chi Oph
table11.dat
62
45
Polarization of Pi Aqr
table12.dat
62
40
Polarization of Omicron And
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Byte-by-byte Description of file: table1.dat
------------------------------------------------------------------------------Bytes
Format
Units
Label
Explanations
------------------------------------------------------------------------------1- 7
A7
--Name
Star name
8-14
I7
--HD
HD catalog number
15-19
I5
--HR
BS catalog number
20-24
F5.2
mag
V
Visual magnitude (BSC4)
25
1X
----Blank
26-40
A15
--Sp
*Spectral type
41-44
I4
km/s
vsini
*vsini
------------------------------------------------------------------------------Notes for file: table1.dat
------------------------------------------------------------------------------Sp, vsini:
According to Slettebak, A. 1982, ApJS, 50, 55
------------------------------------------------------------------------------Byte-by-byte Description of file: table2.dat
------------------------------------------------------------------------------Bytes
Format
Units
Label
Explanations
------------------------------------------------------------------------------1
A1
--Passband
Filter system passband
2- 6
I5
0.1nm
Wavelength Effective wavelength
7-11
I5
0.1nm
FWHM
Bandpass (fwhm)
------------------------------------------------------------------------------Byte-by-byte Description of file: table3.dat table4.dat table5.dat
table6.dat
table7.dat table8.dat table9.dat table10.dat table11.dat table12.dat
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Format
Units
Label
Explanations
------------------------------------------------------------------------------1- 2
I2
mo
Month
Month of observations
3- 5
I3
yr
Year
Year-1900
6
1X
----Blank
7
A1
--Passband
Filter system passband
8-10
I3
--nobs
[]? Number of observations
11-16
F6.2
%
q
[]? Mean normalized Stokes
parameter q
17-21
F5.2
%
dq
[]? Standard deviation in q
22-27
F6.2
%
u
[]? Mean normalized Stokes
parameter u
28-32
F5.2
%
du
[]? Standard deviation in u
33-37
F5.2
%
p
Mean degree of polarization
38-42
F5.2
%
dp
[]? Standard deviation in p
43-48
F6.1
deg
theta
Mean equatorial position angle
49-53
F5.1
deg
dtheta
[]? Standard deviation in theta
54-58
F5.2
%
dpi
*[]? Instrumental precision of q,
u, or p
59-62
F4.1
deg
dthetai
*[]? Instrumental precision of
theta
------------------------------------------------------------------------------Notes for file: table3.dat table4.dat table5.dat table6.dat table7.dat
table8.dat table9.dat table10.dat table11.dat table12.dat
------------------------------------------------------------------------------dpi:
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
dthetai:
dthetai = mean instrumental error in equatorial position angle of the
polarization, based on the relation dthetai=28.65(dpi/p)
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(End)
David McDavid [Limber Obs.] 12Sep-1994