EXOTIC METAL MOLECULES IN OXYGEN-RICH ENVELOPES: DETECTION OF AlOH (X{sup 1}{sigma}{sup +}) IN VY CANIS MAJORIS

Journal Article · Sat Mar 20 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/712/1/L93; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21305080

Tenenbaum, E D

A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris (VY CMa), an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 {yields} 8 and J = 7 {yields} 6 lines at 1 mm were measured with the ARO Submillimeter Telescope, while the J = 5 {yields} 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths of 16-23 km s{sup -1}, as found for NaCl in this source, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H{sub 2} was found to be {approx}1 x 10{sup -7} for a source size of 0.26'' or 22 R{sub *} . In contrast, AlCl was not detected with f {<=} 5 x 10{sup -8}. AlOH is likely formed just beyond the photosphere via thermodynamic equilibrium chemistry and then disappears due to dust condensation. The AlOH/AlO abundance ratio found in VY CMa is {approx}17. Therefore, AlOH appears to be the dominant gas-phase molecular carrier of aluminum in this oxygen-rich shell. Local thermodynamic equilibrium calculations predict that the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides. The apparent predominance of aluminum-bearing molecules in VY CMa may reflect proton addition processes in H-shell burning.

• OSTI ID: 21305080
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 712; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ABUNDANCE
ALUMINIUM
DUSTS
HYDROGEN
LINE WIDTHS
LTE
OXIDES
OXYGEN
PHOTOSPHERE
PROTONS
RADIANT HEAT TRANSFER
SODIUM CHLORIDES
STARS
TELESCOPES