1 / 12

Astronomy 500 November 7, 2008

The Carbon Stars. Astronomy 500 November 7, 2008. The Classical Carbon Star. Stars with luminosities corresponding to late-G, K and M giants but with over abundances of carbon. Come in several flavors: C-R, C-N, C-J,C-H, and C-Hd

caden
Download Presentation

Astronomy 500 November 7, 2008

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Carbon Stars Astronomy 500 November 7, 2008

  2. The Classical Carbon Star • Stars with luminosities corresponding to late-G, K and M giants but with over abundances of carbon. • Come in several flavors: C-R, C-N, C-J,C-H, and C-Hd • Although most are giants or sub-giants, there are also dwarf carbon stars: dC

  3. Collegio Romano Father Angelo Secchi History Circa 1868 +

  4. Spectral Classification System • Originally devised by Keenan and Morgan in 1941 • Revised by Keenan in 1993 to include several classes of carbon stars • Numbers correspond to the strength of the absorption bands

  5. The C-R Stars • Warmest of the carbon stars and most “blue” • Characterized by their prominent Swan bands (C2) at λ4737 and λ5765

  6. The C-N Stars • Generally redder than C-R stars with weaker Swan bands • S-process elements are more prominent

  7. The C-J Stars • Have a remarkably large abundance of 13C (the 12C/13C ratio is less than 13 as compared to 92 in our solar system) • Have significant SiC2 while weaker Ba II and Sr I lines.

  8. The C-H Stars • Dominated by bands of CH in the blue region of the spectrum • Strong (sometimes saturated) G-band which is formed from the Q-branches of the CH (A-X 0-0 and 1-1) bands located near λ4300

  9. The C-Hd Stars • Hydrogen deficient carbon stars with almost complete absence of the G-band and other hydrogen lines. • Stronger than normal of CN and C2

  10. The dC stars • The discovery of the first dwarf carbon star, G77-61, seemed to be a fluke • Characterized by the same lines as their giant cousins but extremely low luminosities • Some have a severe metal deficiency of almost -5.6 dex

  11. References • Wallerstein G, Knapp G. 1998. Annu. Rev. Astrophys.36:369-433 • Dahn CC, et al. 1977. Ap. J. 216:757 • Gray, R.O., Corbally, C.J.; Stellar Spectral Classification. Princeton University Press, Priceton, NJ, 2009. 306-321 • http://www.ucea.it/PreScen/Astronomia.htm • http://www.sil.si.edu/digitalcollections/hst/scientific-identity/CF/display_results.cfm?alpha_sort=s

  12. What does not exist looks so handsome What does exist, where is it? An ocean is hidden. All we see is foam, shapes of dust, spinning, tall as minarets, but I want the wind Dust can’t rise up without wind, I know, but can’t I understand this by some way other than induction? Invisible ocean, wind. Visible foam and dust: This is speech. Why can’t I hear thought? These eyes were born asleep. Why organize a Universe this way? Jalal al-Din Rumi (1207-1273)

More Related