J/AZh/81/1104 Optical spectrum of Cyg OB2 No. 12 (Klochkova+, 2004)
The optical spectrum of the LBV candidate in the Cyg OB2 association.
Klochkova V.G., Chentsov E.L.
<Astron. Zh. 81, 1104 (2004)>
=2004AZh....81.1104K 2004AZh....81.1104K
=2004ARep..48..1005K 2004ARep..48..1005K
ADC_Keywords: Stars, blue; Stars, variable; Equivalent widths; Radial velocities
Abstract:
We have obtained the first high spectral-resolution (R=15000 and
60000) optical spectra for the extremely luminous star No.12,
identified with the IR-source IRAS 20308+4104 in the Cyg OB2
association. We have identified about 200 spectral features at
4552-7939Å, including interstellar NaI, KI and numerous DIBs, which
are in the strongest absorptions in the spectrum, along with the HeI,
CII, SiII lines. A two-dimensional spectral classification indicates
that the star's spectral type is B5±0.5 Ia+. Our analyses of the
radial velocities pattern shows the presence of a radial velocity
gradient in the stellar atmosphere due to the infall of matter onto
the star. The strong H(alpha) emission line displays broad Thompson
wings and time-variable core absorption, providing evidence that the
stellar wind is inhomogeneous and slightly blue-shifted P Cygni
absorption profile. We conclude that the wind is time-variable.
Objects:
-------------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------------
20 32 40.9 +41 14 29 VI CYG 12 = HIP 101364
-------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 65 202 Line identifications, equivalent widths,
residual intensities, and heliocentric radial
velocities for the spectra of Cyg OB2-No.12
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- El Element (1)
8- 14 A7 --- Mult ? Multiplet number
17- 23 F7.2 0.1nm Lambda Wavelength expressed in Angstroem
24 A1 --- u_Lambda [:] Uncertainty flag on Lambda
27- 30 F4.2 0.1nm EW1 ? Equivalent width for June 12, 2001
31 A1 --- u_EW1 [:] Uncertainty flag on EW1
32 A1 --- n_EW1 [*] *: triplets combined equivalent width
34- 37 F4.2 --- r1 ? Residual intensity for June 12, 2001
38 A1 --- u_r1 [:] Uncertainty flag on Lambda
41- 43 I3 km/s HRV1 ? Heliocentric radial velocity for
June 12, 2001
44 A1 --- u_HRV1 [:] Uncertainty flag on HRV1
48- 51 F4.2 0.1nm EW2 ? Equivalent width for April 12, 2003
52 A1 --- u_EW2 [:] Uncertainty flag on EW2
55- 58 F4.2 --- r2 ? Residual intensity for April 12, 2003
59 A1 --- u_r2 [:] Uncertainty flag on Lambda
62- 64 I3 km/s HRV2 ? Heliocentric radial velocity for
April 12, 2003
65 A1 --- u_HRV2 [:] Uncertainty flag on HRV2
--------------------------------------------------------------------------------
Note (1): DIB = extremely strong diffuse interstellar band
--------------------------------------------------------------------------------
(End) Veta Avedisova [INASAN] 06-Apr-2006