Open AccessAccurate positions of H 2 O masers in the Large Magellanic Cloud
Author(s) -
Lazendic J. S.,
Whiteoak J. B.,
Klamer I.,
Harbison P. D.,
Kuiper T. B. H.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05251.x
Subject(s) - maser , physics , large magellanic cloud , astrophysics , astronomy , antenna (radio) , radio telescope , telescope , spitzer space telescope , galaxy , telecommunications , computer science
Positions with subarcsecond accuracy have been measured for seven 22‐GHz H 2 O masers associated with H ii regions in the Large Magellanic Cloud (LMC); two of the masers are new detections. Initial position measurements were obtained with the 70‐m antenna of the Canberra NASA Deep Space Network during a period of more than two years in which the antenna was used to monitor the maser emission. The positions were further improved using 22‐GHz observations involving three antennas of the Australia Telescope Compact Array. The positions have been compared with those of 1.6‐GHz continuum emission and other LMC masers (of OH and CH 3 OH). The H 2 O maser positions range from within 1 arcsec (270 mpc) of the centre of a compact H ii component to beyond the boundary of significant continuum emission. Three of the four masers located near continuum peaks are close to OH masers. In two cases the positional agreement is better than 0.2 arcsec (53 mpc); in the third case the agreement is worse (0.9 arcsec) but the positions of the individual H 2 O features appear to be spread over more than 1 arcsec. The velocities of the OH masers are within the spread of the H 2 O velocities. The three H 2 O masers offset from continuum centres are located 3–7 arcsec from optical or infrared phenomena probably associated with very early stages of star formation; no other molecular masers are known in these directions.