CDROM/PASP/V106/P0949 Multicolor Polarimetry of Be Stars (McDavid 1994) ================================================================================ Multicolor Polarimetry of Selected Be Stars: 1990-93 David McDavid <1994, PASP, 106, 949> =1994PASP..106..949M ================================================================================ 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 -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Bytes 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) -------------------------------------------------------------------------------- ================================================================================ (End) David McDavid [Limber Obs.] 12-Sep-1994