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Please silence your cell phones. AMERICA VOTES! Adric Riedel ASTR86002008 02 05.

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Presentation on theme: "Please silence your cell phones. AMERICA VOTES! Adric Riedel ASTR86002008 02 05."— Presentation transcript:

1 Please silence your cell phones

2 AMERICA VOTES! Adric Riedel ASTR

3 12% of nearby stars are K stars (68% are M stars) K stars are the brightest dwarfs visible to the unaided eye Most of the red color of Pop II stars is K giants All K star temperatures range between roughly 5180K and 3850K Marked by the first appearance of TiO lines Spectra no longer approximate blackbody Not well studied (even the Kaler book has a lot of filler) K dwarfs could have tidally unlocked planets in their habitable zones Commonality of K stars 3 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

4 Luminosity range is smaller for K stars: -9.2 (RW Ceph, K0Ia-0) to 8.46 (HIP 20302, K9V) Luminosity Class VII (White Dwarfs) first appears in K stars (15.43 (GJ 223.2, DZ9) may actually be in the M star range.) Subdwarfs are still distinct in luminosity from Main Sequence stars in the K region. Commonality of K stars 4 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

5 Not all luminosity classes or subtypes are equally meaningful. Keenan, 1985: Spectral Features of K stars 5 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

6 “The letter K represents spectra of the later second type, or intermediate between the second and third types. The letter K may be briefly described as representing the spectra in which the bands K and H, the band G, and the line are the most conspicuous features, and in which the end of the shorter wave length is faint, and the distribution of light is not uniform with different parts of the spectrum. The hydrogen lines in this class are fainter than numerous solar lines” 'Second' and 'Third' are remnants of an earlier system Å is CaI The Henry Draper Catalog (1901) 6 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

7 MKK System (1943) 7 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

8 “The G-band continues to increase in strength until the early K-type stars (about K2) and then begins to fade. The Ca I 4227 line grows gradually in strength until the early K stars, and then becomes dramatically stronger by mid-K... The temperature type may be estimated with precision, even in metal-weak stars by using the ratio of the Cr I 4254 line with the two neighboring Fe I lines at 4250 and Notice that the Cr I line (which arises from a low-lying level) becomes stronger in ratio with the two flanking Fe I lines, being clearly stronger than both by K5. In the K-type dwarfs, the spectral type may be estimated from the ratio of Ca I 4227 to Fe I 4383, in the sense that Ca I/Fe I grows toward later types. By M0, bands due to TiO become visible in the spectrum, and these strengthen quite dramatically toward later types; by M4.5 they dominate the spectrum.” Richard Gray's Spectral Atlas 8 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

9 Classified between 6000A and 9000A, instead of 3800A- 4900A Boundary between K and M set based on continuum slope between 7700A and 8100A Ten types defined, like Cannon (1901), but unlike the MKK system (0,2,3,5) or the revised MK system (added K7 halftype) Beaulieu et al. (2008, in prep) 9 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

10 G band breaks up in cooler subtypes Ca I 4227 Å increases in strength with cooler subtypes Ca II H and K lines weaken with cooler subtypes Ba II visible in giant and supergiant atmospheres (Boeshaar, private communication)... but also more prominent in Barium stars regardless of type. If you look in any atlas of spectral types, you will find the feature at 4077 Å marked as an ultimate line of Sr II, and used as an important criterion in estimating luminosity of the stars. Actually, however, this line is blended with rather strong lines of Y I, La II, Dy II and Fe I ( 4078). The iron line is not sensitive to luminosity, while abundance of the heavy elements is an important factor in determining the strength of the other contributors. (Keenan, 1984) Spectral Features of K stars 10 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

11 Spectral Features of K stars 11 Keenan-McNeil Spectral Atlas Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

12 Heavily studied in the blue part of the spectrum the 'G' band visible in K stars and hotter (where visible) Inversions in the Calcium K bands The 'CN' break at 4215A is stronger for supergiants (though this depends on abundances of Carbon and Nitrogen) Color-magnitude diagrams (also useful for multiplicity) Weeding out luminosity classes 12 Keenan-McNeil Spectral Atlas Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

13 epsilon Pegasi: K2 Ib (Alberio A: K3 II) (Pollux: K0 III & planet) Aldebaran: K5 III Arcturus: K1 III Alpha Centauri B: K1 V epsilon Eridani: K2 V & planet 61 Cygni A&B K5 V & K7 V GJ 223.2: DZ9 (VII) Our Famous K Star Contenders 13 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

14 GJ 223.2: DZ 9 white dwarf 14 SSS plates assembled with Aladin Skyview Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

15 GJ 223.2: DZ 9 white dwarf 15 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

16 epsilon Pegasi: K2 Ib supergiant 16 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

17 Second brightest star in Pegasus, after Alpha Andromeda (!) (http://www.astro.uiuc.edu/~kaler/sow/enif.html) 150 R sun, 10 M sun, 6700 L sun, variable with erratic behavior epsilon Pegasi: K2 Ib supergiant 17 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

18 Aldebaran: K5 III giant 18 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

19 Giant star, has changed to helium fusion 40 R sun, 350 L sun, variable star 13 th brightest star in the sky Aldebaran: K5 III giant 19 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

20 Epsilon Eridani: K2 V dwarf 20 NASA, ESA, and G. Bacon (STScI) Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

21 Nearby young dwarf K star 0.85 M sun, 0.84 R sun, 0.27 L sun. ~600 Myr old (http://www.solstation.com/stars/eps-erid.htm) epsilon Eridani: K2 V dwarf 21 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

22 Alpha Centauri B: K0 V dwarf 22 RECONS Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

23 21 st brightest star in the sky ~17” away from the third brightest star in the sky ~6 Gyr old Only parsecs away 0.92 M sun, 0.51 L sun SUN b GJ0559B V 1.34 K0 V CNS91 RECONSALPHA CEN B, I dare you! Alpha Centauri B: K0 V dwarf 23 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

24 61 Cygni A&B: K5 V & K7 V 24 Lowell Observatory, 1916 & 1951 photos (Possibly assembled by Guy K. McArthur) ‏ Via solstation.com Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

25 61 Cygni AB (K5V, K7V) ‏ and 0.09 Solar Luminosities; 0.6 and 0.5 solar masses Highest proper motion stars known in the 1800s First stars with a known parallax (2/3 arcsec, by Bessel) Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

26 The Morgan & Keenan C,N, and S types extend into K as well, both as giants and dwarfs (Green, P. 1996, IAU symposium) S stars are thought to be halfway between main-sequence stars and C class Carbon Stars, with extra Yttrium and Zirconium in their upper atmospheres. C dwarfs are mass transfer recipients, and are fairly common Various unusual oddballs: C and S stars 26 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

27 Note the extreme VO and ZrO absorption bands that reduce the 'continuum' to spikes. S stars 27 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

28 C 2 bands, CN bands, and apparently presence of C 13 isotopes C stars 28 Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

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30 30 Green, P.J. 1996, IAU #177 invited talk Keenan, P.C. 1985, Calibration of Fundamental Stellar Quantities, 111, 121 Keenan, P.C. 1984, The MK Process and Stellar Classification, 29 Turnshek, et al. “An Atlas of Digital Spectra of Cool Stars” 1985 Star parameters from James Kaler's “Stars”: Politician images courtesy of Google Images Title K star properties K star features Descriptions Luminosity classes Examples: Class VII Class I Class III Class V S and C stars Works Cited

31 Various Oddballs Insert Table of Contents here 31

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