Herschel/HIFI
Observations of EXtraOrdinary
Sources: The Orion and Sagittarius B2 Starforming Regions
HEXOS will use both Herschel/HIFI
and PACS
to perform full line surveys of 5 sources in the Orion and Sagittarius
B2 molecular clouds. These two sources contain the best-studied
examples of physical and chemical processes that are prevalent in the
interstellar medium and associated with the birth of massive stars and
stellar clusters. This includes exploring the physical and chemical
conditions that exist in gas in close proximity to massive stars that
is heating and exposed to shocks, in addition to ambient gas that is
directly exposed to radiation from previous generations of star
formation. Herschel offers unprecedented sensitivity and near
continuous spectral coverage across the gaps imposed by the
atmosphere. This will open up a largely unexplored wavelength regime
to high-resolution spectroscopy. Given that these sources have the
richest emission spectra seen for star-forming regions in the Galaxy,
we anticipate that the proposed observations will define the
sub-millimeter/far infrared region of the spectrum and that these data
will form a lasting Herschel legacy. An example of the results
expected from this program is shown in the figure, where we show a plot of the expected
emission from a variety of astrophysical sources (hot core: warm gas
near a massive star; quiescent gas: very cold—T~20 K—dense material
that is the reservoir for future star formation; shocked gas: gas that
has been subject to a strong dynamical collision with fast-moving
material). As can be seen the spectrum of these objects is distinctly
different and Herschel observations will, for the first-time, directly
characterize the emission from these disparate sources a high spectral
resolution. These type of defining observations are simply not
possible from ground-based observatories, and will be useful for
future far-infrared observations in our Galaxy and beyond.
The HEXOS program will essentially provide a near complete chemical
assay of these organic rich sources, including numerous species that
are of direct astrobiological interest such as water and various
complex organics that are pre-cursors to amino acids and DNA bases.
The opening of this spectral range is also an opportunity to detect
the bending transitions of polycyclic aromatic hydrocarbons, whose
identity has eluded astronomers for decades. Our ultimate aim is to
use these data understand the extent of chemical and physical
processes associated with the birth of stars. These results will also
provide the basis to explore the initial conditions for the supply to
organics to young planetary systems and will directly inform on the
chemical processes responsible for molecular formation.
Program Coordinator: E. Bergin
Sub-Program Coordinators and Members:
- Orion BN/KL Survey:
E.
Bergin, T. Bell, G. Blake, P. Caselli, E. Caux, C. Ceccarelli, C. Comito, M. Guedel, E. Herbst, D. Lis, S. Lord,
S. Maret, J. Pearson, T. Phillips, P. Schilke
- Orion S Survey:
R. Plume, E. Bergin, E. Caux, C. Ceccarelli, D. Johnstone, W. Langer, P. Martin, P. Schilke
- Orion Bar:
M. Spaans, J. Stutzki,
C. Joblin, M. Gerin, E. Herbst, P. Martin, V. Ossenkopf,
M. Roellig, P. Schilke, R. Simon
- Large Molecules:
C. Joblin, G. Blake, J. Cernicharo, E. Herbs, G. Malloci,
G. Mulas, J.
Pearson
- Molecular Oxygen:
P. Goldsmith, C. Ceccarelli, D. Lis, G.
Melnick, C. Vastel
- BN/KL Small Maps:
D. Neufeld, E. Bergin, J.
Cernicharo, J. Goicoechea, G. Melnick,
M. Spaans
- Sgr B2(N) Survey:
D. Lis,
T. Bell, C. Comito, S. Lord,
K. Menten, P. Schilke, J. Zmuidzinas
- Sgr B2(M) Survey:
P. Schilke,
C. Comito, D. Lis,
K. Menten, J. Zmuidzinas
- Sgr B2 L-O-S Clouds:
P. Goldsmith,
T. Bell, M. Gerin, D. Lis, G. Melnick, P. Schilke, C.
Vastel, J. Zmuidzinas
- PACS Scans:
J. Cernicharo, P.
Encrenaz, J. Pardo, J. Rodriguez-Goicoechea, B. Tercero,
- Polarization: M. Harwit,
M. Houde, W. Jellema, G. Melnick,
K. Menten, D.
Neufeld
Last modified:
3/27/2009
