Astronomy 210 Class Work (Feb. 19)
1. Star Formation: the ionized gas
(a) Go to Gems of SINGG.
SINGG stands for Survey for Ionization in Neutral-Gas Galaxies and is a
survey for ionized Hα (Balmer n=3 to n=2) emission. The images on
the page show stars in cyan-blue and Hα as orange-red to yellow.
Red tones indicate locations of newly formed hot stars.
Take a look at the spirals ('Big spirals' and 'Edge-on galaxies' as well
as the ones under 'Pairs').
Write a sentence or two listing your
conclusions about the distribution of star formation regions in spirals.
(b) Look at
a multiwavelength comparison of M51. The image at lower right is
a combination of the molecular (red), atomic (blue), and ionized gas (green)
components of the galaxy. How does the distribution of ionized gas compare
to the molecular? to the atomic? What does this suggest about the location
of star formation?
2. Star Formation: UV, IR, Radio Continuum
Star formation is detected at other wavelengths, including ultraviolet
mid-infrared, and radio continuum.
Open the
Multiwavelength Andromeda Galaxy
and take a look at the images.
Compare the ultraviolet, mid-infrared, far-infrared and
radio continuum ('radio') to
the visible wavelength images. (Note that radio continuum is different from
HI, which is an emission line.) Also see
an animation of images at several wavelengths, including
ionized gas and atomic gas.
(a) Write several sentences comparing the images.
(b) What is each wavelength tracing? (Refer to your notes and the
explanations on the M31 multiwavelength webpage.)
(c) Also check out M81.
(Recall that this was the galaxy with HI extensions toward several dwarf compaions.) and M104, the Sombrero Galaxy. Summarize your observations of these galaxies.
Last updated February 18, 2008