The nature of BX Mon, a peculiar star characterized by a composite spectrum and very long period photometric variability, has been investigated. The star has been included in an extensive program of ESO observations of emission line stars. New results are discussed based on coordinated optical (IDS) and infrared observations made in February 1983, on high resolution H alpha spectrophotometry made with CAT-CES in February 1984, and on infrared photometry of March 1985. The 1983 spectrum is composite with prominent hydrogen and weak He I emission lines, and a cool continuum with strong TiO absorptions. The red-infrared energy distribution, corrected for an interstellar extinction of (B-V) = 0.2, suggests for the cool component an M5 III spectral type in agreement with the strength of the TiO red bands. A distance of 2800 pc is estimated for the system. An excess with respect to the M continuum is present shortward of 600 nm and is attributed to a hotter component and to nebular emission. The 1984 H alpha profile is complex, with two-component emission, and a broad red red-shifted shell absorption probably produced in a wind from the cool giant with a velocity of 59 km/s. The observations indicate that presently the cool M-type component of BX Mon is rather stable - certainly not a Mira variable in agreement with its being an S-type symbiotic. The reported photometric variability could be attributed to the hot component.
Viotti, R., Altamore, A., Ferrari Toniolo, M., Friedjung, M., Persi, P., Rossi, C., et al. (1986). The symbiotic star BX Monocerotis. ASTRONOMY & ASTROPHYSICS, 159, 16-21.
The symbiotic star BX Monocerotis
ALTAMORE, Aldo;
1986-01-01
Abstract
The nature of BX Mon, a peculiar star characterized by a composite spectrum and very long period photometric variability, has been investigated. The star has been included in an extensive program of ESO observations of emission line stars. New results are discussed based on coordinated optical (IDS) and infrared observations made in February 1983, on high resolution H alpha spectrophotometry made with CAT-CES in February 1984, and on infrared photometry of March 1985. The 1983 spectrum is composite with prominent hydrogen and weak He I emission lines, and a cool continuum with strong TiO absorptions. The red-infrared energy distribution, corrected for an interstellar extinction of (B-V) = 0.2, suggests for the cool component an M5 III spectral type in agreement with the strength of the TiO red bands. A distance of 2800 pc is estimated for the system. An excess with respect to the M continuum is present shortward of 600 nm and is attributed to a hotter component and to nebular emission. The 1984 H alpha profile is complex, with two-component emission, and a broad red red-shifted shell absorption probably produced in a wind from the cool giant with a velocity of 59 km/s. The observations indicate that presently the cool M-type component of BX Mon is rather stable - certainly not a Mira variable in agreement with its being an S-type symbiotic. The reported photometric variability could be attributed to the hot component.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
