2004A&A...426..131S


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.18CET01:00:15

2004A&A...426..131S - Astronomy and Astrophysics, volume 426, 131-144 (2004/10-4)

High resolution observations of SiO masers: Comparing the spatial distribution at 43 and 86 GHz.

SORIA-RUIZ R., ALCOLEA J., COLOMER F., BUJARRABAL V., DESMURS J.-F., MARVEL K.B. and DIAMOND P.J.

Abstract (from CDS):

We present sub-milliarcsecond observations of SiO masers in the late-type stars IRC+10011 and χ Cyg. We have used the NRAO Very Long Baseline Array (VLBA) to map the 43GHz (v=1,2 J=1-0) and the 86 GHz (v=1,2 J=2-1) SiO masers. All the transitions have been imaged except the v=2 J=2-1 in IRC+10011. We report the first VLBI map of the v=1 J=2-1 28SiO maser in IRC+10011 as well as the first VLBA images of SiO masers in an S-type Mira variable, χ Cyg. In this paper we have focused on the study of the relative spatial distribution of the different observed lines. We have found that in some cases the observational results are not reproduced by the current theoretical pumping models, either radiative or collisional. In particular, for IRC+10011, the v=1 J=1-0 and J=2-1 28SiO lines have different spatial distributions and emitting region sizes, the J=2-1 emission being located in an outer region of the envelope. For χ Cyg, the distributions also differ, but the sizes of the masing regions are comparable. We suggest that the line overlaps between ro-vibrational transitions of two abundant molecular species, H2O and 28SiO, is a possible explanation for the discrepancies found between the observations and the theoretical predictions. We have introduced this overlapping process in the calculations of the excitation of the SiO molecule. We conclude that the line overlaps can strongly affect the excitation of SiO and may reproduce the unexpected observational results for the two sources studied.

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Journal keyword(s): masers - techniques: interferometric - stars: circumstellar matter - stars: AGB and post-AGB

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 IRC +10011 OH* 01 06 25.9889735162 +12 35 52.890666456   20.7   18.26 14.01 M8 392 0
2 * omi Cet Mi* 02 19 20.79210 -02 58 39.4956   7.63 6.53 5.03   M5-9IIIe+DA 1413 0
3 V* TX Cam Mi* 05 00 51.1569959503 +56 10 54.093107078       14.02   M9-9.5 326 0
4 V* VX Sgr s*r 18 08 04.0431479808 -22 13 26.629744195 11.72 9.41 6.52 3.90 2.11 M8.5Ia 538 0
5 * chi Cyg S* 19 50 33.9243904 +32 54 50.609683 7.02 6.06 4.24 1.81 -0.01 S6-9/1-2e 659 0
6 3C 454.3 QSO 22 53 57.74798 +16 08 53.5611   16.57 16.10 15.22   ~ 2441 2

    Equat.    Gal    SGal    Ecl

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2019.11.18-01:00:15

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