Typical Stellar EvolutionLACC §: 20.2, 21.4, 21.5
• Red Giant Branch
• Horizontal Giant Branch
• Asymptotic Giant Branch
An attempt to answer the “big questions”: What is out there? Where did I come from?
1Thursday, April 29, 2010
HR Diagram
http://outreach.atnf.csiro.au/education/senior/astrophysics/stellarevolution_hrintro.html
2Thursday, April 29, 2010
Low Mass Evolution
http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/W07/Death/Page1.html
3Thursday, April 29, 2010
http://abyss.uoregon.edu/~js/ast122/lectures/lec16.html
The stellar wind causes mass loss for AGB stars. This loss is around 10-4 solar masses per year, which means that in 10,000 years the typical star will dissolve, leaving the central, hot core (the central star in a planetary nebula).
Low and High Mass Evolution
4Thursday, April 29, 2010
http://zebu.uoregon.edu/~imamura/122/images/1_5.gif
Low M Evolution: 1 vs. 5 M☉
Notice how much mass is lost:
1 M☉ to .065 M☉: a loss of 35%
5 M☉ to 1.34 M☉: a loss of 73%
5Thursday, April 29, 2010
http://ircamera.as.arizona.edu/NatSci102/movies/suntrackson.mpg
Low Mass Evolution
6Thursday, April 29, 2010
Main Sequence Turn-Off Point
http://astro.berkeley.edu/~dperley/univage/univage.html
H-R diagrams of two clusters, the open cluster M67 (a young cluster), and the globular cluster M4 (an old cluster). The main sequence is significantly shorter for the older
cluster; the luminosity and temperature of stars at the 'turnoff point' can be used to date these clusters.
7Thursday, April 29, 2010
HR Diagram and Mass
http://physics.uoregon.edu/~jimbrau/astr122/Notes/Chapter17.html
8Thursday, April 29, 2010
Typical Stellar EvolutionLACC §: 20.2, 21.4, 21.5
• Red Giant Branch: H → He in shell; star expands and surface cools (but core temperature increases)
• Horizontal Giant Branch: preceded by a Helium flash; He → C in core, H → He in shell; like a 2nd (brief, semi-return to the) main sequence
• Asymptotic Giant Branch: He → C in shell, H → He in shell; star expands and surface cools (but core temperature increases)
An attempt to answer the “big questions”: What is out there? Where did I come from?
9Thursday, April 29, 2010
LACC HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe,
3rd ed.
• Ch 20, pp. 461-462: 13.
• Ch 22: Tutorial Quizzes accessible from: http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19
Due first class period of the next week (unless there is a test this week, in which case it’s due
before the test).
AstroTeams, be working on your Distance Ladders.
10Thursday, April 29, 2010
Low Mass Stellar EvolutionLACC §: 20.2, 21.4, 21.5
• Hayashi Track
• Typical Evolution
• Planetary Nebula
An attempt to answer the “big questions”: What is out there? Where did I come from?
11Thursday, April 29, 2010
Star Birth -- Hayashi Track
http://www.physics.uc.edu/~sitko/Spring00/4-Starevol/starevol.html
Infrared energy emissions result from the gravitational collapse of the protostar
12Thursday, April 29, 2010
http://abyss.uoregon.edu/~js/ast122/lectures/lec16.html
Low and High Mass Evolution
The stellar wind causes mass loss for AGB stars. This loss is around 10-4 solar masses per year, which means that in 10,000 years the typical star will dissolve, leaving the central, hot core (the central star in a planetary nebula).
13Thursday, April 29, 2010
Low Mass Evolution
http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/W07/Death/Page1.html
14Thursday, April 29, 2010
http://www.ucolick.org/%7Ebolte/AY4_00/week7/low-mass_deathC.html
Planetary NebulaeWith some complications glossed over, the envelope and as much as 50% of the stellar mass is detached from the star and expelled into space leaving the AGB star very hot core exposed.
The high temperature of the "central star" (it is not REALLY a star as there is no fusion energy source) means it has a Planck [or thermal spectrum] curve that peaks way out in the UV and produces many UV and even soft X-ray photons. These collide with the H, He, C and O atoms in the former envelope that we now call a PN. These atoms get ionized, and on recombination the e- drop through the energy levels giving off various lower energy photons (that add up in energy to the original UV or X-ray ionizing photon) as they head for the ground state.
15Thursday, April 29, 2010
http://rst.gsfc.nasa.gov/Front/pne.jpg
Planetary Nebulae
16Thursday, April 29, 2010
http://mais-ccd-spectroscopy.com/Planetary%20Nebula.htm
Planetary Nebulae: Spectrum
17Thursday, April 29, 2010
http://antwrp.gsfc.nasa.gov/apod/ap070629.html
Cat’s Eye Planetary Nebula
http://antwrp.gsfc.nasa.gov/apod/ap080322.html
The Cat's Eye (NGC 6543) is over half a light-year across and represents a final, brief yet glorious phase in the life of a sun-like star. This nebula's
dying central star may have produced the simple, outer pattern of dusty concentric shells by shrugging off outer layers in a series of regular
convulsions. But the formation of the beautiful, more complex inner
structures is not well understood.
At an estimated distance of 3,000 light-years, the faint outer halo is over 5 light-
years across. More recently, some planetary nebulae are found to have halos like this
one, likely formed of material shrugged off during earlier episodes in the star's
evolution. While the planetary nebula phase is thought to last for around 10,000 years, astronomers estimate the age of the outer
filamentary portions of this halo to be 50,000 to 90,000 years.
18Thursday, April 29, 2010
http://oposite.stsci.edu/pubinfo/pr/96/13/Helix.mpg
Planetary Nebulae: A Dying Low Mass (<~10 Msun) Star
19Thursday, April 29, 2010
Low Mass Stellar EvolutionLACC §: 20.2, 21.4, 21.5
• Hayashi Track: for all stars--low and high mass; gravitation contraction heats protostar
• Typical Evolution: Main Sequence → Red Giant → Helium Flash → Horizontal Giant Branch → Asymptotic Giant Branch →
• Planetary Nebula with White Dwarf
An attempt to answer the “big questions”: What is out there? Where did I come from?
20Thursday, April 29, 2010
LACC HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe,
3rd ed.
• Ch 21, p. 485-486: 2 (I want a one word answer), 4&5 (Mention how and where the thermal energy is coming from for each stage: protostar, main sequence, red giant, helium flash, horizontal giant branch, asymptotic giant branch)
• Ch 23: Tutorial Quizzes accessible from: http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19
Due first class period of the next week (unless there is a test this week, in which case it’s due
before the test).
AstroTeams, be working on your Distance Ladders.
21Thursday, April 29, 2010