a1 18 stellar evolution

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




Low Mass Evolution

http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/W07/Death/Page1.html




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




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%




http://ircamera.as.arizona.edu/NatSci102/movies/suntrackson.mpg

Low Mass Evolution






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.




HR Diagram and Mass

http://physics.uoregon.edu/~jimbrau/astr122/Notes/Chapter17.html


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)



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.


http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19






Low Mass Stellar EvolutionLACC §: 20.2, 21.4, 21.5

• Hayashi Track

• Typical Evolution

• Planetary Nebula



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





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).




Low Mass Evolution





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.




http://rst.gsfc.nasa.gov/Front/pne.jpg

Planetary Nebulae






http://mais-ccd-spectroscopy.com/Planetary%20Nebula.htm

Planetary Nebulae: Spectrum




http://antwrp.gsfc.nasa.gov/apod/ap070629.html

Cat’s Eye Planetary Nebula


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.










http://www.atlasoftheuniverse.com/plannebs.html

http://www.atlasoftheuniverse.com/plannebs.html

http://hubblesite.org/newscenter/archive/releases/1997/38

http://hubblesite.org/newscenter/archive/releases/1997/38



http://www.ing.iac.es/~rcorradi/HALOES/

http://www.ing.iac.es/~rcorradi/HALOES/

http://www.astro.washington.edu/balick/WFPC2/

http://www.astro.washington.edu/balick/WFPC2/

http://oposite.stsci.edu/pubinfo/pr/96/13/Helix.mpg

Planetary Nebulae: A Dying Low Mass (<~10 Msun) Star






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



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.








a1 18 stellar evolution

Education

typical star

shell star

low mass evolution http

stellar mass

mass loss

star birth

offdying central star

low mass stellar evolutionlacc