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AMERICA
VOTES!
Adric Riedel
ASTR8600
2008 02 05
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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
3
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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
Commonality of K stars
• Luminosity range is smaller for
K stars: -9.2 (RW Ceph, K0Ia0) to 8.46 (HIP 20302, K9V)
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 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
• 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
5
Spectral Features of K stars
• “The letter K represents spectra of the later second type,
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
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
The Henry Draper Catalog (1901)
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
4030-4034 (Mn I) 4300 (G Band)
K0
4290 (G band)
4300 (G Band)
K0,K2,K3,K5
4226 (CaI)
4325 (Fe I)
K2,K3,K5
4383 (Fe I)
4406 (Continuum) K5
4102 (H I)
4096 (Continuum) K0
Luminosity indicators:
4063 (Fe I)
4077 (Sr II)
K0,K2,K3,K5
4071 (Fe I)
4077 (Sr II)
K0,K2,K3
4045 (Fe I)
4077 (Sr II)
K3
4144 (Fe I)
4077 (Sr II)
K0
4260 (Fe I)
4215 (CN break) K3,K5
4325 (Fe I)
4340 (H I)
K3
Intensity of continuous spectrum across 4215 (K0,K2)
MKK System (1943)
• “The G-band continues to increase in strength until the early
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
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.”
Richard Gray's Spectral Atlas
• Classified between 6000A and 9000A, instead of 3800A-4900A
• Boundary between K and M set based on continuum slope
between 7700A and 8100A
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
• 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)
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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
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
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
11
Spectral Features of K stars
Keenan-McNeil Spectral Atlas
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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)
Title
K star properties• Color-magnitude diagrams (also useful for multiplicity)
K star features
Descriptions
Luminosity classes
Examples:
Class VII
Class I
Class III
Class V
S and C stars
Works Cited
12
Weeding out luminosity classes
• epsilon Pegasi: K2 Ib
• (Alberio A: K3 II)
• (Pollux: K0 III & planet)
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
• 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)
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Our Famous K Star Contenders
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
14
GJ 223.2: DZ 9 white dwarf
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
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
16
epsilon Pegasi: K2 Ib supergiant
• Second brightest star in Pegasus, after Alpha Andromeda (!)
(http://www.astro.uiuc.edu/~kaler/sow/enif.html)
• 150 R sun, 10 Msun, 6700 L sun, 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
17
epsilon Pegasi: K2 Ib supergiant
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
18
Aldebaran: K5 III giant
• Giant star, has changed to helium fusion
• 40 R sun, 350 L sun, 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
19
Aldebaran: K5 III giant
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
20
Epsilon Eridani: K2 V dwarf
• Nearby young dwarf K star
• 0.85 Msun, 0.84 R sun, 0.27 L sun. ~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
21
epsilon Eridani: K2 V dwarf
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
22
Alpha Centauri B: K0 V dwarf
• 21st brightest star in the sky
• ~17” away from the third brightest star in the sky
• ~6 Gyr old
• Only 1.338 parsecs away
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
• 0.92 Msun, 0.51 L sun
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!
Alpha Centauri B: K0 V dwarf
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
24
61 Cygni A&B: K5 V & K7 V
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0.15 and 0.09 Solar Luminosities; 0.6 and 0.5 solar masses
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Highest proper motion stars known in the 1800s
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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
25
61 Cygni AB (K5V, K7V)
• The Morgan & Keenan C,N, and S types extend into K as well,
both as giants and dwarfs (Green, P. 1996, IAU symposium)
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
• 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
• 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
27
S stars
• 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
28
C stars
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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
30
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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
Works Cited