29:50 Modern Astronomy
Fall 2002
Lecture 15...October 9, 2002
Where do stars come from? (Cont.)

Announcements:

• Homework # 4 is on the Web.
• Observing expedition tomorrow night (if clear). Meet at 7:30 in LR1 lobby. Sign up for ride, show up if you have your own wheels. Will be back in town by 9:30. Main attractions: & h Persei star cluster and Pleiades. Also see where Algol is.
• Look at Sun today.

Star Formation

Main question about star formation. Stars are big, dense, watery things. Interstellar space is extremely empty. How do these things come into existence?

Lecture 14 pictures on star clusters and nebulae.

(7) Summary Young stars & star clusters seem embedded in and associated with ``Dark Clouds''.

Intermezzo: Nobel Prizes in Physics

Yesterday the announcement made that three scientists won the 2002 Nobel Prize in Physics for discoveries in astronomy. Two for solar neutrinos.

(8) How can we really be sure the Sun is shining by nuclear reactions? The core is hidden by 695,000 kilometers of opaque gases.

(9) Look again at equations (3), (4), (5) of Lecture 12. Note neutrino in the first reactions. Neutrinos are hard to stop. They can go through a parsec of lead before being stop.

Neutrinos generated in solar core come out directly.

(10) A Neutrino Telescope is a strange device. Look at Figure 17.4, p391 of text. With this instrument, neutrinos from the Sun were first detected by Raymond Davis over 30 years ago.

(11) One of the modern devices is Kamiokande in Japan URL of Kamiokande.

(12) With Kamiokande, we can image the neutrinos emitted from the solar core. We can ``see into'' the core of the Sun and see the nuclear reactions going on there. URL of neutrino Sun.

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