Harvard Astronomy 201b

Module Prototype: Director’s Cut of a WorldWide Telescope Tour

In Special Topics Modules on April 2, 2013 at 4:46 pm

W5: Multigenerational Star Formation

This post, prepared by Alyssa Goodman and used in class on 4/2/13, is intended to give AY201b students an idea of  how ready their interactive module  should be when it is presented, and the level of detail to offer in a presentation.
Click here to view original WWT Tour, or here for Tour description.  Click here to download “Director’s Cut.” In the (Windows or) web version of WWT, go to “Explore, Open…, Tour” and select the file that you’ve downloaded in order to view the Tour. Or (warning, beta!) watch the Director’s Cut tour in WWT/HTML5.

 Background: Who are the original Tour’s authors?

  • Xavier Koenig: A finishing graduate student at the Harvard-Smithsonian Center for Astrophysics when this Tour was created.  His PhD thesis concerned analysis of Spitzer Space Telescope observations of the star-forming region W5.  As of 2013, Dr. Koenig is a postdoctoral fellow at Yale University.

  • Lori Allen: Thesis advisor at the Center for Astrophysics to Xavier Koenig when this Tour was made.  Today, Dr. Allen, is Deputy Director of the Kitt Peak National Observatory.

  • Sanjana Sharma: High-School student at the Winsor School in Boston when this Tour was made.  Sharma was an intern with the WorldWide Telescope Ambassadors group at the Center for Astrophysics before moving to New Haven, where she is in the class of 2014 at Yale.


What points are raised in the WWT Tour narration that could be explored more deeply by an interested viewer? (text in purple, concerning how we know stars ages, are now clickable links within the Tour, as a prototype)

  • small and faint (how small (angle), how faint, #’s)

  • faint diffuse glow, hot gas  (how hot, what does this region look like at other wavelengths)

  • red glow(=warm dust, how warm, and how do we know?)

  • one burst of star formation can cause another (triggered star formation)

  • may have been 3 successive generations of star formation (how do we know which generation is which?)

  • stars…dispersed over time (how fast, how much time? how do we know?)

  • large clusters (what’s the definition of a “cluster” and is it different for young stars?)

  • changing light they emit to infer the presence of multiple objects (how?)

  • disk…that could maybe form planets (discuss how & whether this “hostile” environment matters)

  • comet-shaped tail that glows in the infrared (how does that happen?)

  • pillars compressed from outside…squeezed on inside by internal gravity (how, which forces do what on what time scales?)

  • brand-new stars are emerging (how do we know they are new?)

  • comparison of pillars/mountains W5/Eagle nebula same scale (angular/linear?…turns out both, as these sources are coincidentally at similar distances from us!)

 Additional Resources

  • Video: Spitzer “Hidden Universe” interviews with Allen & Koenig about W5
  • PhD Thesis: Xavier Koenig’s thesis (PDF)

  • Journal Article: Koenig et al. 2008, Clustered and Triggered Star formation in W5: Observations with Spitzer (ADS link)  [Abstract: We present images and initial results from our extensive Spitzer Space Telescope imaging survey of the W5 H II region with the Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS). We detect dense clusters of stars, centered on the O stars HD 18326, BD +60 586, HD 17505, and HD 17520. At 24 μm, substantial extended emission is visible, presumably from heated dust grains that survive in the strongly ionizing environment of the H II region. With photometry of more than 18,000 point sources, we analyze the clustering properties of objects classified as young stars by their IR spectral energy distributions (a total of 2064 sources) across the region using a minimal-spanning-tree algorithm. We find ~40%-70% of infrared excess sources belong to clusters with >=10 members. We find that within the evacuated cavities of the H II regions that make up W5, the ratio of Class II to Class I sources is ~7 times higher than for objects coincident with molecular gas as traced by 12CO emission and near-IR extinction maps. We attribute this contrast to an age difference between the two locations and postulate that at least two distinct generations of star formation are visible across W5. Our preliminary analysis shows that triggering is a plausible mechanism to explain the multiple generations of star formation in W5 and merits further investigation.]

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