Workshop Ringberg-April 13-17, 2004

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SUBMILLIMETER STUDY OF STAR FORMING REGIONS
AND RADIATIVE TRANSFER MODELING -- AN APPROACH
R. S. THAMPI, PRL, INDIA
Workshop Ringberg-April 13-17, 2004
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PLAN OF MY PRESENTATION
OVER VIEW OF OUR PROGRAME
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MOLECULES AS COOLENTS
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• ROLE OF
  HYDRIDES IN ISM
• Simple hydride molecules are of great importance
  in astrophysics and astro-chemistry.
• Physically they dominate the cooling of dense,
  warm phases of the ISM, such as the cores and
  disks of YSOs.
• Chemically they are often stable end points of
  chemical reactions, or may represent important
  intermediate stages of the reaction chains, which
  can be used to test the validity of the process.
• Due to the low moment of inertia, the hydrides
  rotate rapidly and so have their fundamental
  spectral lines in the submillimeter.
• Depending on the cloud geometry and temperature
  profile they may be observed in emission or
  absorption.
• Species such as HCl, HF, OH, CH, CH, NH2, NH3,
• H2O, H2S, H3O and even H3 have been detected.
• For example, the most important coolant for many
  regions, H2O, has a possible range of deduced
  abundance of a factor of 1000.
• In circum stellar envelopes and planetary
  nebulae, the CH and OH radicals are predicted to
  be the products of photochemical processes which
  depend on a variety of factors, and since CH and
  OH contain three of the most abundant elements in
  the stellar ejecta, their transitions near 2 THz
  will be critical indicators for these processes.
  In particular, CH has strong transitions at
  180.6, 149.5, 149.2, and 125.0 ?m with low-lying
  energy levels.

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Atmospheric Important molecules Atmospheric Important molecules Interstellar molecules Interstellar molecules
Molecules Frequency (GHz) Molecules Frequency (GHz)
BrO 624.8, 650.2 H2O ortho, H2O-para 556.936 1669.905, 1113.343
HCl 625.9 O2 2502.3
HO2 649.7, 660.5 H2O 2531.9
H2O 2532 O3 2509.6
OH 2509, 2514 H37Cl 625.9
O3 625,625.4, 2509,2543 N2O 652.8
O2 2502 CH3CN 624.8,626.4
CH3CN 660.7 81BrO 624.8
SO2 660.9, 624.9, 625.8 H2O2 625
81BrO 624.8,650.2 HNO3 624.6,650
H2O2 625 HF LiH,, NaH 1232.476 , 887.2 868.6
H37Cl 625 CH 532.8, 536.8
HNO3 624.6,650 KH, CuH 202, 404, 468
HOCl 625.1 HCO 624.087
HO2 649.7,660.5 NH2D HDO, D2O 494.454 893.639, 607.3496
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SUBMILLIMETER STUDY OF STAR FORMING REGIONS
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SITE-MAP
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SUBMILLIMETER INSTRUMENTATION
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OPTICALLY PUMPED MOLECULAR LASER
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SCHOTTKY DIODE
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Superconductor-Insulator- Superconductor (SIS)
Mixer
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Bolometers
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BACKEND ELECTRONICS
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LABORATORY SETUP
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RADIATIVE TRANSFER MODELING
Why modeling of star forming regions ? Star
forming interstellar clouds are in fact complex
systems they have irregular three-dimensional
shapes and complicated velocity fields, the
densities extend over many orders of magnitude,
and the temperatures range from about 10K to
several million K. There are myriads of reactions
going on among the particles. The relevant
geometric scales range from atomic sizes to light
years.
We then compare these models with observations
taken from telescopes and satellites
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RT EQUATION
Using more than one transition from the same
molecule can give detailed information on its
excitation temperature, which in turn is related
to the kinetic temperature and density of the
gas, and velocity component along the line of
sight, using the Doppler shift. Combining this
with optically thin emission from isotopomer
species, the depth along the line of sight can be
studied. The wealth of molecular lines can
together give a full description of the physics
and chemistry of STAR FORMING REGIONS
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DATA ANALYSIS AND RADIATIVE TRANSFER MODELING
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INTERNATIONAL CONFERENCE ON SUBMILLIMETER SCIENCE
AND TECHNOLOGY- ICSST04
THANK YOU
Workshop Ringberg-April 13-17, 2004