J/A+A/311/484 CH Cyg 1991-1995 UBV-JHKLM photometry (Munari+, 1996)
UBV-JHKLM photometry of CH Cygni over 1978-1995: dust properties and doubts on
the triple star model.
Munari U., Yudin B.F., Kolotilov E.A., Tomov T.V.
<Astron. Astrophys. 311, 484 (1996)>
=1996A&A...311..484M 1996A&A...311..484M (SIMBAD/NED BibCode)
ADC_Keywords: Photometry, UBVRIJKLMNH
Keywords: binaries: symbiotic - individual stars: CH Cyg - infrared stars
Abstract:
We present new UBV-JHKLM photoelectric photometry of the symbiotic
binary CH Cyg covering the period 1991-1995, which extend our
monitoring started in 1978. The large and highly homogeneous set of
data that we have accumulated in the last eighteen years is reviewed
and discussed. By July 1995 the outbursting component has returned to
the same conditions which characterized the previous minimum in
1988-1989. In J, H, K CH Cyg shows a long term modulation that can be
fitted with a sinusoid of 32 year period. It may be a dust obscuration
event similar to those known to undergo in symbiotic Miras. The cool
giant exhibits in the infrared a variability of large amplitude, best
described as chaotic-like. The only detectable periodicity is 1980
days. The photometric properties of the cool giant denounce a clear
partnership with the spheroidal component of the Galaxy. This lowers
the estimated distance to ∼120pc and the cool giant mass to
∼1.0M☉. Several episodes of dust condensation in the wind of the
giant are identified. One is in full progress at the time of writing.
The dust condensation temperature is found to be ∼1,000K. The
condensed dust grains absorb selectively in the infrared but are large
enough to absorb neutrally in the UBV wavelength region. There is no
evidence for dust condensing in an hypothetical wind or ejected
material from the outbursting white dwarf. The recently proposed
triple-star model for CH Cyg is confronted with photometric
observations. Several serious discrepancies are outlined and
individually discussed. We believe that, without additional evidences
and careful modelling, the triple star model cannot survive the
comparison with the photometric observations. The low amplitude
(2.6km/s) and periodic (756 days) radial velocity variations
apparently do not trace an orbital motion. They may be due to one of
the many superimposed pulsation modes of the highly variable M giant.
Objects:
---------------------------------------------------------
RA (2000) DE Name
---------------------------------------------------------
19 24 33.0 +50 14 30 CH Cyg = HD 182917 = BD+49 2999
---------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1 25 58 1991-1995 CH Cyg UBV photoelectric photometry
table1.tex 73 64 LaTeX version of table1
table2 36 35 1991-1995 CH Cyg JHKLM photoelectric photometry
table2.tex 75 51 LaTeX version of table2
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 I7 d JD Julian date
9- 13 F5.2 mag Umag U magnitude
15- 19 F5.2 mag Bmag B magnitude
21- 24 F4.2 mag Vmag V magnitude
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 I7 d JD Julian date
9- 12 F4.2 mag Jmag J magnitude
14- 18 F5.2 mag Hmag ? H magnitude
20- 24 F5.2 mag Kmag ? K magnitude
26- 30 F5.2 mag Lmag ? L magnitude
32- 36 F5.2 mag Mmag ? M magnitude
--------------------------------------------------------------------------------
(End) Patricia Bauer [CDS] 02-Apr-1996