Resolving the circumstellar environment of the Galactic B[e] supergiant star MWC 137, II : nebular kinematics and stellar variability
| Autor: | Alexei Moiseev, David O. Jones, Dieter H. Nickeler, Julieta Paz Sánchez Arias, Lydia Sonia Cidale, T. Liimets, Michaela Kraus |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
individual (MWC 137) [stars]
Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences circumstellar matter Spectral line Nordic Optical Telescope law.invention early-type [stars] Telescope purl.org/becyt/ford/1 [https] massive [stars] law 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Emission spectrum 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics::Galaxy Astrophysics Physics Solar mass Nebula 010308 nuclear & particles physics Astronomy and Astrophysics purl.org/becyt/ford/1.3 [https] Astrophysics - Astrophysics of Galaxies Photometry (astronomy) Astrophysics - Solar and Stellar Astrophysics 13. Climate action Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Astrophysics::Earth and Planetary Astrophysics Supergiant |
| Zdroj: | CONICET Digital (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas instacron:CONICET The Astronomical Journal |
| Popis: | The Galactic B[e] supergiant MWC 137 is surrounded by a large-scale optical nebula. To shed light on the physical conditions and kinematics of the nebula, we analyze the optical forbidden emission lines [NII] 6548,6583 and [SII] 6716,6731 in long-slit spectra taken with ALFOSC at the Nordic Optical Telescope. The radial velocities display a complex behavior but, in general, the northern nebular features are predominantly approaching while the southern ones are mostly receding. The electron density shows strong variations across the nebula with values spreading from about zero to ~800 cm$^{-3}$. Higher densities are found closer to MWC~137 and in regions of intense emission, whereas in regions with high radial velocities the density decreases significantly. We also observe the entire nebula in the two [SII] lines with the scanning Fabry-Perot interferometer attached to the 6-m telescope of the Special Astrophysical Observatory. These data reveal a new bow-shaped feature at PA = 225-245 and a distance 80" from MWC 137. A new H$\alpha$ image has been taken with the Danish 1.54-m telescope on La Silla. No expansion or changes in the nebular morphology appear within 18.1 years. We derive a mass of 37 (+9/-5) solar masses and an age of $4.7\pm0.8$ Myr for MWC 137. Furthermore, we detect a period of 1.93 d in the time series photometry collected with the TESS satellite, which could suggest stellar pulsations. Other, low-frequency variability is seen as well. Whether these signals are caused by internal gravity waves in the early-type star or by variability in the wind and circumstellar matter currently cannot be distinguished. Comment: 18 pages, 12 figures, Table 1 is only available in electronic form, submitted to AJ |
| Databáze: | OpenAIRE |
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