The First Detection of Diffuse Interstellar [OII] Emission from the Milky Way using Spatial Heterodyne Spectroscopy

Computer Science – Performance

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

Scientific paper

Using a newly developed Spatial Heterodyne Spectrometer (SHS), we have achieved the first detection of diffuse [OII] 372.6 nm and 372.9 nm emission lines from the warm (10,000 K), low density (0.1 cm-3) ionized component of our Galaxy's interstellar medium (WIM). These [OII] lines are a principal coolant for this wide spread, photoionized gas and are a potential tracer of variations in the gas temperature resulting from unidentified interstellar heating processes that appear to be acting within the Galaxy's disk and halo. We have also detected numerous, weak airglow lines, including terrestrial [OII] emission.
In our SHS system, Fizeau fringes of wavenumber-dependent spatial frequency are produced by a Michelson interferometer modified by replacing the return mirrors with diffraction gratings. These fringes are recorded on a position sensitive detector and Fourier transformed to recover a spectrum over a limited range centered at the grating Littrow wavenumber. SHS combines interferometric and field-widening gains to achieve sensitivities much larger than conventional grating instruments of similar size and resolving power, and comparable to the Wisconsin Hα Mapper (WHAM) Fabry-Perot, but in the near UV where WHAM cannot observe.
Our early results confirm the superb performance of the SHS technique for measurements of spatially extended faint emissions, including the first detection of [OII] emission lines extending out to 20 degrees from the Galactic equator in the longitude range of 110 to 150 degrees. [OII] intensities range from tens of Rayleighs near the Galactic plane to less than one Rayleigh at high Galactic latitudes. The [OII] line profiles clearly show structure indicating emission along the lines of sight from both local interstellar gas and more distant gas in the Perseus spiral arm. Preliminary line ratio comparisons with WHAM [NII] (658.4 nm) and Hα (656.3 nm) observations confirm the utility of the [OII] observations as a temperature diagnostic for the WIM. This work is supported by the National Science Foundation through grants AST-0138228 and AST-0138197. The Wisconsin Hα Mapper is funded by the National Science Foundation through grant AST- 0204973.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

The First Detection of Diffuse Interstellar [OII] Emission from the Milky Way using Spatial Heterodyne Spectroscopy does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The First Detection of Diffuse Interstellar [OII] Emission from the Milky Way using Spatial Heterodyne Spectroscopy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The First Detection of Diffuse Interstellar [OII] Emission from the Milky Way using Spatial Heterodyne Spectroscopy will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-1643458

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.