Initial Sciences with the SMA

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Initial Sciences with the SMA

• Hiroko Shinnaga
• Harvard-Smithsonian Center for Astrophysics
• Submillimeter Array (SMA)

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The Submillimeter Array

• Eight 6-m diameter dish antennas
• Baseline 8 508 m
• Up to 200 m baselines tried so far.
• Receivers 230 GHz, 345 GHz (to be dual
  polarization), 690 GHz bands
• To come on line ? 820 GHz, 460 GHz bands
• Maximum resolution e.g. 0.2 at 345 GHz
• Field of View 60 15
• Location 4080m in altitude
• Good weather condition
• Tau at 225 GHz 0.05 weather
• ? 10 during May November
• ? 27 during December April
• Sensitivity e.g., DS 2mJy at 345 GHz 20 mJy
  for 690 GHz under 1mm water vapor level, with 8
  hours integration time

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The Submillimeter Array

• Location Valley at the summit of Mauna Kea
• Reuleaux triangle configurations
• Interferometer shapes offer the most complete
  sampling in the Fourier space of the image
• (Keto 1997).

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Antenna Configurations

• Keto 1997

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Reuleaux Triangle

• Keto 1997

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Bandwidth and Correlator Setting
USB 2 GHz
LSB 2 GHz
10 GHz separation

• Bandwidth 2GHz for each sideband
• Freq. resolution
• 250 kHz at the highest end
• 406 kHz, 812 kHz modes are commonly used.

Beuther et al. in prep.
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Massive Star IRAS18089-1732
1mm band
0.8mm band
Beuther et al. in prep.
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SMA Initial 7 Science Projects
2. Low-mass star forming regions/disks
1. Solar System
3. High-mass stars
6. Nearby galaxy
7. Distant galaxy
4. Evolved star
5. Galactic Center

• 16 papers will be published in ApJL.

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Evolved Star Project

• Evolved stars are interesting targets to study.
• Image disks and outflows of nearby sources.
• Detect polarization of molecular emission to
  investigate circumstellar magnetic field.
• Study (episodic) mass loss activity.
• Study chemistry surrounding the envelope.
• Four papers are being prepared from the project.
• V Hya CO 3-2, 2-1 imaging
• IRC10216 CS 14-13 imaging
• EP Aqr CO 2-1 imaging
• VY CMa SiO 5-4 v1 maser imaging polarization
  measurements

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Submillimeter Frequencies

• Synthesis imaging of
• CO 2-1, 3-2, 6-5
• CS 14-13
• HCN 4-3
• Masers (SiO, H2O).
• Etc

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IRC10216 CS 14-13 Imaging

• Young et al. 2004

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IRC10216 CS 14-13 Imaging

• Young et al. 2004

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658 GHz Water Maser
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V Hya CO 2-1 / 3-2

• Hirano, Shinnaga et al. in prep.

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Interferometric Observations of SiO High J
Transition Maser Associated With VY CMa With the
SMA

• Hiroko Shinnaga
• Harvard-Smithsonian Center for Astrophysics
• Submillimeter Array (SMA)

Collaborators James M.Moran, Ken H. Young, Paul
T.P. Ho
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Images of SiO High J Maser Spots

• Taking advantage of high s/n ratio, relative
  positions of maser spots can be measured with
  reasonable accuracies by fitting 2D Gaussian.
• Typical position accuracy
• 100 x 150 mas.
• Plot made assuming the component 2 is located
  at the position of the star.
• Seem to trace the edge of the SiO bipolar
  outflows structure.
• A couple of maser spots are located outer
  circumstellar region.
• Due to higher optical depth compared to low J
  transitions?