Title: But I am constant as the Northern Star Of whose truefixed and resting quality There is no fellow in
1But I am constant as the Northern StarOf whose
true-fixed and resting qualityThere is no fellow
in the firmament.'' William
Shakespeare,
Julius Caesar, 3, 1
2Astronomy C - Variable Stars - 2008
A. Pulsating Variables 1) Long Period
Variables a) Mira type b)
Semiregular 2) Cepheids 3) RR Lyrae B.
Cataclysmic (Eruptive) Variables 1) R
Coronae Borealis 2) Flare Stars 3)
Dwarf Novae 4) X-Ray Binaries 5)
Supernovae a) Type II b) Type
Ia C. Strangers in the Night
3Astronomy C - Variable Stars - 2008
A. Pulsating Variables 1) Long Period
Variables a) Mira type R Cygni
b) Semiregular V725 SGR 2) Cepheids W
Virginis 3) RR Lyrae AH Leo B. Cataclysmic
(Eruptive) Variables 1) R Coronae Borealis
RY Sagittarii 2) Flare Stars UV Ceti
3) Dwarf Novae SU Ursae Majoris 4) X-Ray
Binaries J1655-40, RX J0806.31527 5)
Supernovae a) Type II G11.2-0.3,
SN2006gy b) Type Ia DEM L71,
Keplers SNR C. Strangers in the Night V838 Mon
4Light Curves Variation over Time
Maximum (Maxima)
Minimum (Minima)
Period
Apparent Magnitude vs Julian Day
5A. Pulsating Variable Stars 1) Long Period
Variables (LPVs)
a) Miras
80 1000 days, 2.5 5.0 mag
R Cygni
b) Semiregular Variables
30 1000 days, 1.0 2.0 mag
V725 Sgr
6Semiregular
Mira Instability Strip
72) Cepheid Variable Stars W Virginis (Type
2) Periods of .8 35 days, .3 1.2 mag
8Type I and Type II Cepheid Variable Stars
Type I (Classical) Cepheids Young
high-metallicity stars about 4 times more
luminous than Type II Cepheids Type II
Cepheids Older low-metallicity stars about 4
times less luminous than classical Cepheids.
93) RR Lyrae Variable Stars AH Leo Periods
of .2 1 day, .3 2.0 mag
10Cepheid and RR Lyrae Variable Stars
Period-Luminosity Relationship and The Distance
Modulus
M m -
5log10 (r)
10
Mv 0.75
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12Cepheid Instability Strip
Semiregular
RR Lyrae
Mira Instability Strip
13B. Cataclysmic (Eruptive) Variables
Irregular Period, up to 3 mag
RY Sagittarii
142) Flare Stars faint cool red dwarfs
irregular and unpredictable
UV Ceti
153) Dwarf Novae
Dwarf Novae Close Binary Systems Sun-like main
sequence star, white dwarf , accretion disk
SU Ursae Majoris
Period 30-500 days, 2-5 mag
164) X-Ray Binaries Close Binary Systems
White Dwarf, Neutron Star, or Black Hole
accreting material from a Companion Star
GRO J1655-40
a)
RX J0806.31527
b)
175) Supernovae a) Type II Core Collapse of
a Massive Star
G11.2-0.3
SN 2006gy
18b) Type Ia Thermonuclear Destruction of a
White Dwarf in a Binary System
Keplers SNR
DEM L71
19Supernovae Light Curves
20C. Strangers in the Night
V838 Mon
21AH Leo
W Virginis
R Cygni
V725 SGR
Type II G11.2-0.3, SN 2006gy Type Ia DEM L71,
Kepler
SU Ursae Majoris
RY Sagittarii
Flare Stars UV Ceti
X-Ray Binaries GRO J1655, RXJ0806.31527
???
V838 Mon
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25?
?
26Cosmological Distances
Variables
Cepheids RR Lyrae
Spectroscopic Parallax
27Cosmological Distances
?Spectroscopic Parallax
The Distance Modulus M m - 5log10 (r)
10
?Cepheids
d The Distance Modulus M m - 5log10 (r)
10
28Cosmological Distances Candles
?Type Ia Supernovae Standard Candle
Mv -19.5
29Basic Equations and Relationships
The Distance Modulus M m - 5log10 (r)
10 Keplers 3rd Law (MA MB) a3
p2 v d a v 2p a
vP Fc mac ac v2 r?2 t
t
r 1 pc 206,265 au 3.26
ly 3.08 x 1016m 1 60 arcmin 60 1
60 arcsec 60? Inverse Square Law L
1/r2 Circumference, Area, Surface Area, and
Volume of a Sphere
REARRANGE ALL EQUATIONS FOR EACH VARIABLE
30Phase Diagrams
1) Cepheid Light Curve
2) Superposition of Periods
4) Same data starting at Maxima
3) Same Data Plotted Twice
31 O C Diagrams (Observed minus
Calculated)
Theory Matches Observation
Perfectly Periodic
Perfectly Periodic
Perfectly Periodic
Correct Epoch
Change in Period
Wrong Period
Correct Epoch Correct Period
True Period Shorter then Lenthens
True Period longer
Perfectly Periodic
Periodic
NOT Perfectly Periodic
Period Unchanged Epoch has Changed
Correct Period Wrong Epoch
Different Period Each Day
The slope of each line is the difference
between its period and the estimated period.
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35Stellar Evolution A Journey with Chandra
36Stellar Evolution A Journey with Chandra
37Stellar Cycles Sets and Cosmic Connections
Request URL
http//chandra.harvard.edu/edu/epo/request_special
.html
Stellar Cycles Card Set
38Additional Resources
39The American Association of Variable Star
Observers
40http//www.soinc.org/store/TG-DVD-06v10.htm
UPDATED COACHES MANUAL COMING SOON!!!
(AVAILABLE ONLINE AT THE NSO WEBSITE)