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• Please silence your cell phones

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AMERICA VOTES!
Adric Riedel ASTR8600 2008 02 05
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• 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

• 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

Commonality of K stars
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• 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.

• 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

Commonality of K stars
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• Not all luminosity classes or subtypes are
  equally meaningful.
• Keenan, 1985

• 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

Spectral Features of K stars
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• 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
  4227.0 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
• 4227.0Å is CaI

• 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

The Henry Draper Catalog (1901)
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• 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

MKK System (1943)
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• 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 4260... 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.

• 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

Richard Gray's Spectral Atlas
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• 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)

• 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

Beaulieu et al. (2008, in prep)
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• 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)

• 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

Spectral Features of K stars
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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

Spectral Features of K stars
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Keenan-McNeil Spectral Atlas

• 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)

• 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

Weeding out luminosity classes
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• 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 AB K5 V K7 V
• GJ 223.2 DZ9 (VII)

• 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

Our Famous K Star Contenders
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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

GJ 223.2 DZ 9 white dwarf
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• 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

GJ 223.2 DZ 9 white dwarf
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http//www.seds.org/messier/Pics/More/m15cnoao.jpg

• 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

epsilon Pegasi K2 Ib supergiant
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• Second brightest star in Pegasus, after Alpha
  Andromeda (!) (http//www.astro.uiuc.edu/kaler/so
  w/enif.html)
• 150 Rsun, 10 Msun, 6700 Lsun, variable with
  erratic behavior

• 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

epsilon Pegasi K2 Ib supergiant
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http//www.df9cy.de/image_astro/moon_aldebaran.jpg

• 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

Aldebaran K5 III giant
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• Giant star, has changed to helium fusion
• 40 Rsun, 350 Lsun, variable star
• 13th brightest star in the sky

• 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

Aldebaran K5 III giant
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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

Epsilon Eridani K2 V dwarf
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• Nearby young dwarf K star
• 0.85 Msun, 0.84 Rsun, 0.27 Lsun. 600 Myr old
  (http//www.solstation.com/stars/eps-erid.htm)

• 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

epsilon Eridani K2 V dwarf
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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

Alpha Centauri B K0 V dwarf
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• 21st brightest star in the sky
• 17 away from the third brightest star in the
  sky
• 6 Gyr old
• Only 1.338 parsecs away
• 0.92 Msun, 0.51 Lsun
• SUN 14 39 35.1 -60 50 14.0 3.724 284.8 3 b
  GJ0559B V 1.34 K0 V CNS91 RECONS ALPHA CEN B, I
  dare you!

• 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

Alpha Centauri B K0 V dwarf
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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

61 Cygni AB K5 V K7 V
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• 0.15 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

61 Cygni AB (K5V, K7V)?
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• 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

• 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

Various unusual oddballs C and S stars
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• Note the extreme VO and ZrO absorption bands that
  reduce the 'continuum' to spikes.

• 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

S stars
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• C2 bands, CN bands, and apparently presence of
  C13 isotopes

• 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

C stars
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America's New K Star!
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• 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
  http//www.astro.uiuc.edu/kaler/sow/sowlist.html
• 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

Works Cited
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Various Oddballs
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