Time monitoring observations of SiO J = 2-1 and J = 3-2 maser emission toward late-type stars

Jina Kang, Se Hyung Cho, Hyun Goo Kim, Hyun Soo Chung, Hyo Ryung Kim, Duk Gyoo Roh, Chang Won Lee, Sang Joon Kim

Research output: Contribution to journalArticlepeer-review

Abstract

We present the results of simultaneous time monitoring observations of SiO J = 2-1 and J = 3-2 maser emission for 10 late-type stars (8 Mira variables, 1 OH/IR star, and 1 supergiant) with the 14 m radio telescope at Taeduk Radio Astronomy Observatory from 1999 January to 2001 February. The SiO v = 1, J = 2-1 and J = 3-2 maser emission was detected at almost all observational epochs. The SiO v = 2, J = 2-1 maser was detected from 4 late-type stars (VY CMa, R Cas, χ Cyg, R Leo) and the v = 2, J = 3-2 maser was detected from 7 stars (R Aqr, TX Cam, R Cas, χ Cyg, W Hya, R Leo, IK Tau). The v = 3, J = 2-1 and J = 3-2 masers were also detected from χ Cyg and TX Cam, respectively. Based on these observational data, line profile and peak velocity variations with respect to stellar velocity, antenna temperatures, and their ratio variations as a function of optical phase of central star were investigated. As main results, the line profile and the peak velocity variation of the v = 1.J = 3-2 maser with pulsation phase was found to differ from the v = 1, J = 2-1 transition. Similarly, the J = 2-1 and J = 3-2 transitions also differ between rovibrational transitions at a given pulsation phase. However, it is difficult to find significant correlations between the peak velocity variation relative to the stellar velocity of either the J = 3-2 or, J = 2-1 transitions over pulsation phase, due to limited time sampling in these data. The peak and integrated antenna temperature (PT and IT) ratios among rotational ladders and vibrational states are investigated. These ratios between rotational ladders of the v = 1, J = 2-1, and J = 3-2 masers are averaged to be the peak antenna temperature ratio, PT(v = 1, J = 3-2)/PT(v = 1, J = 2-1) ≈ 0.29, and the integrated antenna temperature ratio, IT(v = 1. J = 3-2)/IT(v = 1, J = 2-1) ≈ 0.21, respectively. In the v = 2 state, these ratios are PT(v = 2, J = 3-2)/PT(v = 2, J = 2-1) ≈ 7.94 and IT(v = 2. J = 3-2)/IT(v = 2, J = 2-1) ≈ 8.50, respectively. The peak and integrated antenna temperature ratios between vibrational states are also averaged to be PT(v = 2, J = 3-2)/PT(v = 1, J = 3-2) ≈ 1.29, IT(v = 2. J = 3-2)/IT(v = 1. J = 3-2) ≈ 1.02, PT(v = 2. J = 2-1)/PT(v = 1. J = 2-1) ≈ 0.06, and IT(v = 2. J = 2-1)/IT(v = 1, J = 2-1) ≈ 0.05, respectively. These intensity ratios for the r = 2. J = 2-1 and r = 2, J = 3-2 masers suggest that line overlaps operating in the v = 2, J = 2-1 transition do not similarly affect the v =2, J = 3-2 transition.

Original languageEnglish (US)
Pages (from-to)360-385
Number of pages26
JournalAstrophysical Journal, Supplement Series
Volume165
Issue number1
DOIs
StatePublished - Jul 2006
Externally publishedYes

Keywords

  • Circumstellar matter
  • Masers
  • Stars: late-type
  • Stars: oscillations

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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