2014AJ....148...97D -
Astron. J., 148, 97 (2014/November-0)
Astrometrically registered simultaneous observations of the 22 GHz H2O and 43 GHz SiO masers toward R Leonis Minoris using KVN and Source/Frequency phase referencing.
DODSON R., RIOJA M.J., JUNG T.-H., SOHN B.-W., BYUN D.-Y., CHO S.-H., LEE S.-S., KIM J., KIM K.-T., OH C.-S., HAN S.-T., JE D.-H., CHUNG M.-H., WI S.-O., KANG J., LEE J.-W., CHUNG H., KIM H.-R., KIM H.-G., LEE C.-H., ROH D.-G., OH S.-J., YEOM J.-H., SONG M.-G. and KANG Y.-W.
Abstract (from CDS):
Oxygen-rich asymptotic giant branch (AGB) stars can be intense emitters of SiO (v = 1 and 2, J = 1 ⟶ 0) and H2 O maser lines at 43 and 22 GHz, respectively. Very long baseline interferometry (VLBI) observations of the maser emission provide a unique tool to probe the innermost layers of the circumstellar envelopes in AGB stars. Nevertheless, the difficulties in achieving astrometrically aligned H2O and v = 1 and v = 2 SiO maser maps have traditionally limited the physical constraints that can be placed on the SiO maser pumping mechanism. We present phase-referenced simultaneous spectral-line VLBI images for the SiO v = 1 and v = 2, J = 1 ⟶ 0, and H2O maser emission around the AGB star R LMi, obtained from the Korean VLBI Network (KVN). The simultaneous multi-channel receivers of the KVN offer great possibilities for astrometry in the frequency domain. With this facility, we have produced images with bona fide absolute astrometric registration between high-frequency maser transitions of different species to provide the positions of the H2 O maser emission and the center of the SiO maser emission, hence reducing the uncertainty in the proper motions for R LMi by an order of magnitude over that from Hipparcos. This is the first successful demonstration of source frequency phase referencing for millimeter VLBI spectral-line observations and also where the ratio between the frequencies is not an integer.
Abstract Copyright:
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Journal keyword(s):
astrometry - masers - stars: AGB and post-AGB - stars: individual: RLMi - techniques: interferometric
Simbad objects:
4
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