J/ApJ/786/120 Spectropolarimetric survey of classical Be stars (Draper+, 2014)
Disk-loss and disk-renewal phases in classical Be stars.
II. Contrasting with stable and variable disks.
Draper Z.H., Wisniewski J.P., Bjorkman K.S., Meade M.R., Haubois X.,
Mota B.C., Carciofi A.C., Bjorkman J.E.
<Astrophys. J., 786, 120 (2014)>
=2014ApJ...786..120D 2014ApJ...786..120D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Be ; Spectral types ; Effective temperatures ;
Polarization ; Equivalent widths
Keywords: circumstellar matter -
stars: individual: pi Aqr, 60 Cyg, 48 Lib, psi Per, phi Per, 28 Cyg,
66 Oph, gamma Casseopia, omega Ori, FY CMa, 59 Cyg
Abstract:
Recent observational and theoretical studies of classical Be stars
have established the utility of polarization color diagrams (PCDs) in
helping to constrain the time-dependent mass decretion rates of these
systems. We expand on our pilot observational study of this
phenomenon, and report the detailed analysis of a long-term
(1989-2004) spectropolarimetric survey of nine additional classical Be
stars, including systems exhibiting evidence of partial
disk-loss/disk-growth episodes as well as systems exhibiting long-term
stable disks. After carefully characterizing and removing the
interstellar polarization along the line of sight to each of these
targets, we analyze their intrinsic polarization behavior. We find
that many steady-state Be disks pause at the top of the PCD, as
predicted by theory. We also observe sharp declines in the Balmer jump
polarization for later spectral type, near edge-on steady-state disks,
again as recently predicted by theory, likely caused when the base
density of the disk is very high, and the outer region of the edge-on
disk starts to self absorb a significant number of Balmer jump
photons. The intrinsic V-band polarization and polarization position
angle of γ Cas exhibits variations that seem to phase with the
orbital period of a known one-armed density structure in this disk,
similar to the theoretical predictions of Halonen & Jones. We also
observe stochastic jumps in the intrinsic polarization across the
Balmer jump of several known Be+sdO systems, and speculate that the
thermal inflation of part of the outer region of these disks could be
responsible for producing this observational phenomenon. Finally, we
estimate the base densities of this sample of stars to be between
∼8x10-11 and ∼4x10-12 g/cm3 during quasi steady state periods
given there maximum observed polarization.
Description:
The spectropolarimetric data analyzed in this study were obtained by
the University of Wisconsin's HPOL spectropolarimeter, mounted on the
0.9 m Pine Bluff Observatory (PBO) telescope. Data obtained before
1995 were recorded using a dual Reticon array detector spanning the
wavelength range of 3200-7600 Å with a spectral resolution of 25 Å
(Wolff et al. 1996AJ....111..856W 1996AJ....111..856W). Beginning in 1995, HPOL's detector
was upgraded to a 400x1200 pixel CCD camera that provided coverage
from 3200 to 6020 Å at a resolution of 10 Å and 5980-10500 Å
at a resolution of 7 Å (Nordsieck & Harris 1996, Polarimetry of the
Interstellar Medium (ASP Conf. Ser. 97), ed. W. G. Roberge & D. C. B.
Whittet (San Francisco, CA: ASP), 1000).
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
15 58 11.37 -14 16 45.7 48 Lib = HD 142983
03 36 29.38 +48 11 33.5 psi Per = HD 22192
01 43 39.64 +50 41 19.4 phi Per = HD 10516
20 09 25.62 +36 50 22.6 28 Cyg = HD 191610
18 00 15.80 +04 22 07.0 66 Oph = HD 164284
00 56 42.53 +60 43 00.3 gamma Casseopia = HD 5394
05 39 11.15 +04 07 17.3 omega Ori = HD 37490
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File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 78 11 Target Star Summary
table2.dat 50 151 Raw HPOL Data
table5.dat 45 151 Intrinsic Polarization
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See also:
II/220 : Polarisation of Be stars (McDavid, 1986-1999)
J/PASP/106/949 : Multicolor polarimetry of Be stars (McDavid, 1994)
J/A+A/368/912 : Polarization and rotational velocities of Be stars
(Yudin, 2001)
J/A+A/440/305 : Fundamental parameters of fast-rotating B stars
(Fremat+, 2005)
J/A+A/459/137 : Bright Be shell stars (Rivnius+, 2006)
J/ApJ/709/1306 : Spectropolarimetry of 60 Cyg and π Aqr
(Wisniewski+, 2010)
J/other/BASI/39.517 : Spectroscopy of classical Be stars (Mathew+, 2011)
J/A+A/550/A79 : Hα and Hβ lines of northern Be stars
(Catanzaro, 2013)
J/ApJ/768/128 : K-band calibrated visibilities of 24 Be stars
(Touhami+, 2013)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Name Target identifier
18- 25 A8 --- SpType Spectral type (1)
27- 31 I5 deg Teff Effective temperature
33- 35 I3 deg e_Teff ? Uncertainty in Teff
37 I1 --- r_Teff [1/3] Teff reference (2)
39 A1 --- l_Inc1 [~] Limit flag on Inc1
40- 43 A4 deg Inc1 ? Disk inclination
45 I1 deg e_Inc1 ? Uncertainty in Inc1
47- 49 A3 --- r_Inc1 Inc1 reference(s) (3)
51- 52 I2 deg Inc2 ? Disk inclination
54 I1 --- r_Inc2 [6]? Inc2 reference (3)
56- 57 I2 --- HPOLRet [2/53] Number of HPOL Reticon Nights
59- 60 I2 --- HPOLCCD [3/57] Number of HPOL CCD Nights
62- 68 A7 --- WUPPE Wisconsin Ultraviolet Photo-Polarimeter
Experiment (WUPPE) observation ? (4)
70- 78 A9 --- SName Short name used in tables 2 and 5
--------------------------------------------------------------------------------
Note (1): Spectral types were adopted from SIMBAD, except for 48 Lib which is
identified as B3 in a more detailed study (Stefl et al. 2012A&A...540A..76S 2012A&A...540A..76S).
Note (2): Reference as follows:
1 = Fremat et al. (2005, J/A+A/440/305);
2 = Cantanzaro (2013, J/A+A/550/A79);
3 = Koubsky et al. (2000A&A...356..913K 2000A&A...356..913K).
Note (3): Reference as follows:
4 = Delaa et al. (2011A&A...529A..87D 2011A&A...529A..87D);
5 = Touhami et al. (2013, J/ApJ/768/128);
6 = Fremat et al. (2005, J/A+A/440/305);
7 = Rivinius et al. (2006, J/A+A/459/137);
8 = Stefl et al. (2012A&A...540A..76S 2012A&A...540A..76S).
Note (4): If the target was observed with the Wisconsin Ultraviolet
Photo-Polarimeter Experiment (WUPPE), the mission which took the data is
listed.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- SName Target identifier
14- 22 F9.1 d JD Julian Date of observation
24- 29 F6.3 % Q Raw V band Q polarization
31- 37 F7.4 % U Raw V band U polarization
39- 43 F5.3 % Error Error in the polarization
45- 50 F6.2 0.1nm EW Hα equivalent width; Angstroms
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- SName Target identifier
14- 22 F9.1 d JD Julian Date of observation
24- 30 F7.4 % Q Intrinsic V band Q polarization
32- 38 F7.4 % U Intrinsic V band U polarization
40- 45 F6.4 % Error Error in the polarization
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Wisniewski et al., Paper I, 2010ApJ...709.1306W 2010ApJ...709.1306W, Cat. J/ApJ/709/1306
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 22-Jun-2017