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ksp:simultaneous_monitoring_of_kvn_4_bands_toward_evolved_stars [2015/03/12 10:40]
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ksp:simultaneous_monitoring_of_kvn_4_bands_toward_evolved_stars [2015/03/12 17:25]
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 |  Dong-Hwan Yoon  |  dhyoon83@kasi.re.kr  |  SNU/KASI (Doctor course)  |   |  Dong-Hwan Yoon  |  dhyoon83@kasi.re.kr  |  SNU/KASI (Doctor course)  |  
 |  Dong-Jin Kim    |     djkim89@kasi.re.kr    Yonsei Univ/KASI (Master course)  |   |  Dong-Jin Kim    |     djkim89@kasi.re.kr    Yonsei Univ/KASI (Master course)  |  
-|  Sung-Chul Yoon  |    yoon@astro.snu.ac.kr  |  SNU  +|  Sung-Chul Yoon  |    yoon@astro.snu.ac.kr  |  SNU  |
 |  Richard Dodson  |    rdodson@kasi.re.kr    |   ICRAR (Australia)  |   |  Richard Dodson  |    rdodson@kasi.re.kr    |   ICRAR (Australia)  |  
 |  Maria Rioja           maria.rioja@uwa.edu.au  |  OAN (Spain)  |   |  Maria Rioja           maria.rioja@uwa.edu.au  |  OAN (Spain)  |  
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 ==== Status of Research Progress (Details for KVN Evolved Star KSP members ► KVN ES Wiki Page) ==== ==== Status of Research Progress (Details for KVN Evolved Star KSP members ► KVN ES Wiki Page) ====
 +
 +=== KVN Single Dish Surveys and Monitoring Observations ===
 +
 +At the first stage of KVN single dish operation, we have carried out simultaneous surveys of SiO and H2O masers toward 166 evolved stars which are known as both SiO and H2O maser sources. We detected both SiO and H2O masers from 112 stars at one epoch (Kim et al. 2010, Paper I). As the second and third surveys, we have carried out those observations toward previous 83 SiO-only detected sources and 152 H2O-only detected sources, respectively (Cho & Kim 2012: Paper II, Kim, Cho, & Kim 2013: Paper III).
 +We insured a large number of new both SiO and H2O maser sources. We also performed statistical studies based on these homogeneous data (Kim, Cho, & Kim 2014: Paper IV). Simultaneous observations of SiO and H2O masers toward 252 OH/IR stars (Cho et al. 2013), 164 post-AGB and 132 AGB stars (Yoon et al. 2014), and 47 symbiotic stars (Cho et al. 2010) were added. 
 +Based on these surveys, we have also performed monitoring observations toward about 60 relatively strong SiO and H2O maser sources for single dish researches and future KVN and KaVA (KVN+VERA) VLBI observations. They are composed of semi-regular variables, Mira variables, OH/IR stars, and several post-AGB stars including water fountain sources at different evolutionary stages. From 2014A observing season, we selected 16 KVN KSP candidate sources and performed regular intensive monitoring of 22 GHz H2O and 43/86/129 GHz SiO maser lines. 
 +
 +=== VLBI Feasibility Test Observations for Key Science Program ===
 +
 +A simultaneous fringe survey at 22/43/86/129 GHz bands was performed toward 41 sources in 2013 April (Yun et al. 2015 in prep.). The objects were selected from KVN single dish monitoring sources including 7 water fountain sources and post-AGB stars. Five frequencies of H2O: 22.235 GHz, SiO v = 1, J = 1-0: 43.122 GHz, SiO v = 2, J = 1-0: 42.821 GHz, SiO v = 1, J = 2-1: 86.243 GHz, and SiO v = 1, J = 3-2: 129.363 GHz were observed simultaneously. On source integration time was from 30 to 70 minutes depending on sources. The correlation was done with the DiFX correlator. As a result, both SiO and H2O maser fringes were detected from 15 sources among 30 both H2O and SiO maser sources (50%) at one epoch. The fringe of 129 GHz SiO maser was detected from 6 sources (17%) and fringes at all 4 bands were detected from 4 sources. The fringe detection rates of 22, 43, 86 GHz bands were 62, 83, 54 %, respectively. We also performed 4 band snapshot imaging observations toward 14 sources in 2013 May. On source integration time of snapshot was from 40 to 160 minutes. The sample snapshot images of VY CMa simultaneously obtained at 4 bands are shown in Figure 4. These results of the fringe survey and the snapshot
 +imaging inform a promising future of simultaneous observations at four bands of KVN. We also carried out full track imaging at 4 bands toward several stars via Open Use and pilot project of KSP. All four-band images including 129 GHz were obtained from VY CMa, IK Tau (Cho et al. 2015 in prep.). For registering these different maser lines, Multi-Frequency Phase Referencing (MFPR) was highly required together with astrometry. Therefore, SFPR technique for KSP with the astrometric alignment of the SiO masers with respect to H2O maser emission are under testing like R LMi by Dodson et al. (2014).
 +
 +|  {{ :ksp:esksp-fig1.jpg?600 |}}  |
 +| Figure: Snapshot image of maser spots observed from supergiant VY CMa. All maser lines were observed simultaneously at 4 bands for 1 hour. From the very left panel, each image corresponds to 22 GHz H2O, 43 GHz SiO, 42 GHz SiO, 86 GHz SiO, and 129 GHz SiO, respectively. The color bar of 22 GHz H2O maser map represents the velocity along the line of sight, and the color bar of SiO maser maps represents the integrated intensity. The contour of 129 GHz SiO maser map also represents the integrated intensity. |
 +==== Related Publications ====
 +
 +Jaeheon Kim, Se-Hyung Cho, Chung Sik Oh, & Do-Young Byun, "Simultaneous Observations of SiO and H2O Masers toward Known Stellar SiO and H2O Maser Sources. I.", ApJS, 188, 209 (Paper I), 2010 April 
 +
 +Se-Hyung Cho & Jaeheon Kim, "Simultaneous Observations of SiO and H2O Masers toward Symbiotic Stars", ApJ, 719, 126, 2010 August   
 +
 +Se-Hyung Cho & Jaeheon Kim, "Simultaneous Observations of SiO and H2O Masers toward Known Stellar SiO Maser Sources", AJ, 144, 129 (Paper II), 2012 November
 +
 +Jaeheon Kim, Se-Hyung Cho, & Sang Joon Kim, "Simultaneous Observations of SiO and H2O Masers toward Known Stellar H2O Maser Sources", AJ, 145, 22 (Paper III), 2013 January 
 +
 +Jaeheon Kim, Se-Hyung Cho, & Sang Joon Kim, "Statistical Study Based on Simultaneous SiO and H2O Maser Surveys toward Evolved Stars", AJ, 147, 22 (Paper IV), 2014 January
 +
 +Dong-Hwan Yoon, Se-Hyung Cho, Jaeheon Kim, Young Joo Yun, & Yong-Sun Park, “SiO and H2O Maser Survey toward Post-AGB and AGB Stars”, ApJS, 211, 15, 2014 March
 +
 +Dodson, Richard, Rioja, María, Jung, Tae-Hyun et al., “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” AJ, 148, 97, 2014 November 
 +
 +Se-Hyung Cho, Jaeheon Kim, & Youngjoo Yun, “First Detection of 22 GHz H2O Masers in TX Camelopardalis”, JKAS, 47, 293, 2014 December
 +
 +Chi-Young Cho, Se-Hyung Cho et al., “SiO and H2O Maser Survey toward OH/IR Stars” 2013 MS Thesis (Sejong Univ.), 2015 ApJS in prep
 +
 +
 +
 +
  
  
  
  
ksp/simultaneous_monitoring_of_kvn_4_bands_toward_evolved_stars.txt · Last modified: 2019/04/11 10:23 (external edit)