Transcript for X-Ray Spectroscopy of Supernova Remnants

Slide 1:
I am Donna Young and I work with the NASA/Chandra X-Ray Center outreach office. This is an overview and introduction to the DS9 X-Ray Spectroscopy of Supernova Remnants investigation developed by the Chandra mission. For a more comprehensive introduction to the DS9 image analysis software and individual investigations, please watch the short webinar introduction at the beginning of the imaging section.

Slide 2:
The Chandra X-Ray Observatory is in an extreme orbit that ranges from 16,000 km at closest approach to Earth to more than a third of the distance to the moon. The highly inclined orbit takes 64 hours with 55 uninterrupted hours of observing time. The 2 sets of 4 nested hyperbolic/parabolic mirrors match the grazing incidence of the incoming X-Ray photons and direct them to a focal point at the end of the spacecraft. The photons are detected by one of two scientific instruments – the HRC (high resolution camera) or ACIS (advanced CCD imaging spectrometer). A high energy transmission grating is lowered into the focal plane with the ACIS and a low energy transmission grating for the HRC.

Slide 3:
The photons are detected, converted to a voltage and recorded. Every 8 hours there is a data download to the Deep Space Network (DSN) in Spain, Australia or Goldstone in Barstow, CA. The data is then transmitted through the system to Cambridge, MA where the data is analyzed by Chandra scientists. Unique to X-Ray observations and the mirror/grating/scientific instruments aboard the Chandra spacecraft, for each individual X-ray photon detected the amount of energy, the position (x-y coordinates) and time arrival are known – resulting in a high resolution analysis of the objects being observed.

Slide 4:
There is an extensive teachers guide for this investigation and an answer key, as well as both a pencil and paper version and the version that requires the use of the ds9 image analysis software. The student handout gives a very brief description of the 2 types of supernova events. If a large group is participating in this analysis and the teacher wants to ensure that everyone is on the same skill level, it might be appropriate to do the first two remnants with the pencil and paper version before accessing the Ds9 tools.

Slide 5:
The download instructions for the ds9 software are located at http://chandra-ed.harvard.edu/. The software can be downloaded to Windows, MacOSX or Linux environments. The website also has self-guided tutorials and activities to learn how to use the software and the analysis tools. All the instructions and websites are included within the Analyzing the Ages of Supernova Remnants (SNRs) student handout, so students do not need to learn the software beforehand, or use the tutorials or activities unless the teacher requires it.

Slide 6:
There is a 6-page detailed introduction and background that teachers may download in the pdf format in preparation to starting this investigation. It explains the differences between the Type Ia supernova events (thermonuclear explosion of a white dwarf) and Type II events – the catastrophic collapse of a massive star.

Slide 7:
In the pencil and paper version show here, which uses a screen shot from Ds9; students identify emission lines, and calculate a scale for Kev/cm to identify the amount of energy in Kev for each emission line.

Slide 8:
Students then use the table for energies from X-Ray emission lines to match each emission line with a specific element. The investigation leads students through the analysis of both a Type Ia and a Type II event. The SNRs can be located in the Photo Album to determine if the students have the correct results.

Slide 9:
A task specific scoring rubric is provided to use in assessing the understanding and communication of that understanding by the students. Since the students now know how to use the ds9 tools to analyze the elemental composition for both a Type Ia and Type II supernova event, they can now use those same tools to analyze the spectrum of other supernova remnants in the Chandra X-Ray Center public archive to determine whether they are Type Ia or Type II. Once the results have been determined, students can access the selected SNRs in the Photo Album and determine if their answers agree with the scientific findings.

Slide 10:
The Chandra educational materials website has excellent supporting resources for multiwavelength astronomy and stellar evolution. You can request available ancillary classroom materials using the materials request form. If you have any questions, please email me.