A new HCN maser in IRAS 15082-4808

Abstract

We have identified a new vibrational HCN maser at 89.087 GHz in the asymptotic giant branch (AGB) star IRAS 15082-4808, a maser which is thought to trace the innermost region of an AGB envelope. The observations of this maser at three epochs are presented: two positive detections and one null detection. The line profile has varied between the positive detections, as has the intensity of the maser. The major component of the maser is found to be offset by -2.0+/-0.9 km/s with respect to the systemic velocity of the envelope, as derived from the 88.631 GHz transition of HCN. Similar blueshifts are measured in the other 9 sources where this maser has been detected. Maser variability with pulsation phase has been investigated for the first time using the 10 stars now available. Comparisons with AGB model atmospheres constrain the position of the formation region of the maser to the region between the pulsation shocks and the onset of dust acceleration, between 2 and 4 stellar radii.

11 pages, 10 figures, accepted MNRAS, minor correction to equation 1

References in corpus (4)

• SiO in C-rich circumstellar envelopes of AGB stars: effects of non-LTE chemistry and grain adsorption
• Evolved star water maser cloud size determined by star size
• Linear polarization of submillimetre masers. Tracing magnetic fields with ALMA
• Polarization morphology of SiO masers in the circumstellar envelope of the AGB star R Cassiopeiae

Cited by in corpus (5)

• Widespread HCN maser emission in carbon-rich evolved stars
• Radiative Transfer of HCN: Interpreting observations of hyperfine anomalies
• A molecular line survey of a sample of AGB stars and planetary nebulae
• Charting Circumstellar Chemistry of Carbon-rich AGB Stars: I. ALMA 3 mm spectral surveys
• Vibrationally excited HCN transitions in circumstellar envelopes of carbon-rich AGB stars