Transcript No Slide Title

Announcements
Homework #10: due today
Solutions and study guides will be posted
online.
Final Exam scheduled for May 22nd @
12:15. Bring a scantron form 882-EZ
Need extra help? Come to SCI 242 on
Thursday, 5/17, at either 10AM or 3PM.
1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Stellar Remnants:
White Dwarfs, Neutron Stars, & Black Holes
(Chp. 14)
2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Black Holes:
• Progenitor mass: > 10-20 MSun
• Schwarzscild Radius
• Event Horizon
• What is the event horizon for a 1 MSun object?
• Observational Evidence for the existence of BH’s
• X-Ray Binaries
• Center of the Milky Way
3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Eclipsing X-Ray Binaries
Accretion disk emits x-ray radiation
4
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Mass of central object:
3 Million MSun!!
Orbit of S2: P=15.2 years; a=900 AU
Mass according to Kepler’s laws: 3.5x106 MSun!
Luminosity: below detection threshold
Closest approach: 17 light-hours
5
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
The Milky Way Galaxy
(Chp. 15)
6
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Looking up at the sky at night, we can see that
the Sun is one of (at least) thousands of stars.
We also see that the stars in the sky are not
uniformly spread out.
7
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Very thin (100-1000 pc)
9
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Milky Way
NGC 891
11
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
NGC 1232
12
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Angle between Solar System plane and Galactic plane
 62 degrees
13
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
14
Artist’s depiction of solar system seen from Sedna
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
• Disk
– Distribution of stars, gas, and dust with a diameter
of about 30 kpc (100,000 light-years) and plane
tilted with respect to Earth’s orbit around Sun
– Rotation with all objects circling in the same
direction
– High density of stars near center (10 million stars
per cubic light-year) to low density farther out
(0.003 stars per cubic light-year at Sun)
15
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
• Halo
– Roughly spherical region (disk embedded)
– Contains mainly old stars, such as globular
clusters
• Bulge
– Flattened collection of stars surrounding dense
core of galaxy
– About 1/3 the diameter of the galaxy
16
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
17
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
18
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
19
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Spiral Density Wave: galactic traffic jam
20
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Milky Way:
• Herschel’s star counts
• Shapley’s work with globular clusters
• size (50,000 pc across; 100-1000 pc thick)
• location of Sun (8,000 pc from center)
• Components: bulge, disk, halo
• Motion
• bulge versus disk
• direction of Sun’s motion with respect to spiral arms
• Angle between ecliptic and Milky Way
• Spiral Structure
• “traffic jam”
• young stars found in spiral arms
21
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
4 billion miles from home…
22
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Earth, Moon,
and Jupiter as
seen from
Mars
23
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
24
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
25
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
26
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
The Pale Blue Dot
27
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display