Open AccessProper Motions of Dust Shells Surrounding NML Cygni
Author(s) -
W. C. Danchi,
W. H. Green,
D. D. S. Hale,
Kathryn E. McElroy,
John D. Monnier,
Peter Tuthill,
C. H. Townes
Publication year - 2001
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/322237
Subject(s) - physics , astrophysics , supergiant , wavelength , luminosity , proper motion , radial velocity , maser , circumstellar dust , outflow , angular diameter , astronomy , star (game theory) , stars , optics , galaxy , meteorology
The distribution of dust emitted by the supergiant star NML Cygni has been resolved by interferometry at 11 μm wavelengths at various times over a period of 6 yr. Results show there are two discrete dust shells, which have both moved away from the star approximately the same amount during the 6 yr period. This allows determination of the time between ejection of material forming the two shells to be 65 ± 14 yr. Assuming the radial outflow velocity can be derived from Doppler-measured velocities of masers surrounding the star, its distance can be calculated from the observed angular motion to be 1220 ± 300 pc. This decreases the luminosity of the star by about 1 mag over that deduced from the distance 1900 pc previously assumed.
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