HIGH-RESOLUTION VLBA OBSERVATIONS OF THREE 7 mm SiO MASERS TOWARD VX Sgr AT FIVE EPOCHS

Journal Article · Fri Jul 20 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/754/1/47· OSTI ID:22039292

Su, J B; Shen, Z -Q; Chen, X; Jiang, D R ^[1]; Jiyune, Yi ^[2]; Yun, Y J ^[3]

---

1. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China)
2. Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)
3. Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)

VX Sgr is a red supergiant at an adopted distance of 1.6 kpc with intense 43 GHz SiO maser emission. In this paper, we present the high-resolution very long baseline interferometry (VLBI) observations of SiO masers toward VX Sgr at five epochs. We used the Very Long Baseline Array to map the J = 1{yields}0 (v = 1, 2) {sup 28}SiO masers and confirmed a ring-like structure. In the first two epochs, the v = 1 masers form a ring, but v = 2 maser spots residing only in the southern and northern regions do not form a complete ring. In the third epoch, the two masers are distributed in a ring structure and the v = 2 masers are a bit closer to the central star. In the last two epochs, many new maser spots appear and overlap each other. These overlapping maser spots can be related to the shock waves and reflect the collisional pumping. We compare the observations with the pumping models and speculate that the real pumping mechanism may be complex in VX Sgr and vary with time. The J = 1{yields}0 (v = 0) {sup 29}SiO line emission is also detected, but is too weak to produce any VLBI map.

• OSTI ID: 22039292
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 754; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
COMPARATIVE EVALUATIONS
DISTANCE
EMISSION SPECTRA
GHZ RANGE
INTERFEROMETRY
MASERS
RESOLUTION
SHOCK WAVES
SILICON 29
SILICON OXIDES
STARS