A Spectroscopic and Photometric Study of MWC 342 and Its B[e] Phenomenon over the Last 40 Years
Akniyazova A.Z. Miroshnichenko A.S. Zharikov S.V. Van Winckel H. Manset N. Raj A. Chojnowski S.D. Khokhlov S.A. Reva I.V. Kokumbaeva R.I. Omarov C.T. Grankin K.N. Agishev A.T. Vaidman N.L.
June 2025Multidisciplinary Digital Publishing Institute (MDPI)
Galaxies
2025#13Issue 3
MWC 342 (V1972 Cyg) was discovered nearly 90 years ago as an early-type emission-line star. It was among the first hot stars whose strong infrared excess was detected in the early 1970s. Several mostly short-term photometric and spectroscopic studies resulted in contradictory conclusions about the nature and evolutionary status of MWC 342. It has been classified as a pre-main-sequence Herbig Be star, an evolved suspected binary system, and a long-period variable star. Suggestions on the nature of the secondary component to this B0/B1 primary included a cool M-type giant and an X-ray source. We collected medium- and high-resolution optical spectra of MWC 342 taken in 1994–2024 as well as optical photometric data taken in 1986–2024. Analysis of these data shows strong variations in the object’s brightness and spectral line properties at various time scales, but no strictly periodic phenomena have been found. Inparticular, such a long-term dataset allowed us to reveal the optical brightness variations over a nearly 20-year-long quasi-period, as well as their anti-correlation with the H (Formula presented.) emission-line strength. Also, we did not confirm the presence of He ii emission lines and absorption lines of the star’s atmosphere that were suspected in previously published studies.
circumstellar matter , emission-line stars , photometry , spectroscopy
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Faculty of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi Ave., 71, Almaty, 050040, Kazakhstan
Department of Physics and Astronomy, University of North Carolina—Greensboro, Greensboro, 27402, NC, United States
Fesenkov Astrophysical Institute, Observatory, 23, Almaty, 050020, Kazakhstan
Instituto de Astronomía, Universidad Nacional Autónoma de Mexico, AP 106, BC, Ensenada, 22800, Mexico
Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D bus 2401, Leuven, 3001, Belgium
Canada-France-Hawaii Telescope Corporation, 65–1238 Mamalahoa Hwy, Kamuela, 96743, HI, United States
Indian Centre for Space Physics, 466 Barakhola, Netai Nagar, West Bengal, Kolkata, 700099, India
Uttar Pradesh State Institute of Forensic Science (UPSIFS), Aurawan, P.O. Banthra, Uttar Pradesh, Lucknow, 226401, India
NASA Ames Research Center, Moffett Field, 94035, CA, United States
Crimean Astrophysical Observatory, Scientific Research Institute, Nauchny, 298409, Russian Federation
Faculty of Physics and Technology
Department of Physics and Astronomy
Fesenkov Astrophysical Institute
Instituto de Astronomía
Instituut voor Sterrenkunde
Canada-France-Hawaii Telescope Corporation
Indian Centre for Space Physics
Uttar Pradesh State Institute of Forensic Science (UPSIFS)
NASA Ames Research Center
Crimean Astrophysical Observatory
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