``But I am constant as the Northern Star Of whose true-fixed and resting quality There is no fellow in the firmament.'' William Shakespeare, Julius Caesar, 3, 1
``But I am constant as the Northern Star
Of whose true-fixed and resting quality
There is no fellow in the firmament.''
William Shakespeare,
Julius Caesar, 3, 1
Astronomy C -
Variable Stars -
2008
A. Pulsating Variables:1) Long Period Variables
a) Mira typeb) Semiregular
2) Cepheids3) RR Lyrae
B. Cataclysmic (Eruptive) Variables:1) R Coronae Borealis2) Flare Stars3) Dwarf Novae4) X-Ray Binaries5) Supernovae
a) Type IIb) Type Ia
C. Strangers in the Night
Astronomy C -
Variable Stars -
2008
A. Pulsating Variables:1) Long Period Variables
a) Mira type R Cygnib) Semiregular
V725 SGR
2) Cepheids
W Virginis
3) RR Lyrae
AH Leo
B. Cataclysmic (Eruptive) Variables:1) R Coronae Borealis RY Sagittarii2) Flare Stars UV Ceti3) Dwarf Novae SU Ursae
Majoris
4) X-Ray Binaries J1655-40, RX J0806.3+15275) Supernovae
a) Type II G11.2-0.3, SN2006gy b) Type Ia
DEM L71, Kepler’s
SNR
C. Strangers in the Night: V838 Mon
Light Curves –
Variation over TimeMaximum (Maxima)
Minimum (Minima) Period
Apparent Magnitude vs
Julian Day
A. Pulsating Variable Stars; 1) Long Period Variables (LPVs)
a) Miras
R Cygni
b) Semiregular
Variables
80 –
1000 days, 2.5 –
5.0 mag
30 –
1000 days, 1.0 –
2.0 mag
V725 Sgr
Mira Instability Strip
Semiregular
2) Cepheid Variable StarsW Virginis
(Type 2) [Periods of .8 –
35 days, .3 –
1.2 mag]
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.
Type I and Type II Cepheid Variable Stars
3) RR Lyrae
Variable StarsAH Leo
[Periods of .2 –
1 day, .3 –
2.0 mag]
Cepheid and RR Lyrae
Variable Stars
[Mv
= 0.75]
Period-Luminosity Relationship and The Distance Modulus:
M = m -
5log10 (r)
10
Mira Instability Strip
Semiregular
CepheidInstability Strip
RR Lyrae
B. Cataclysmic (Eruptive) Variables1)
R Coronae Borealis
RY Sagittarii
[Irregular Period, up to 3 mag]
2) Flare Stars –
faint cool red dwarfs[irregular and unpredictable] UV Ceti
3) Dwarf NovaeDwarf Novae: Close Binary Systems
Sun-like main sequence star, white dwarf , accretion disk
SU Ursae
Majoris [Period 30-500 days, 2-5 mag]
4) X-Ray Binaries –
Close Binary Systems
GRO J1655-40
RX J0806.3+1527
White Dwarf, Neutron Star, orBlack Hole accreting material from a Companion Star
a)
b)
5) Supernovae a) Type II –
Core Collapse of a Massive Star
G11.2-0.3 SN 2006gy
b) Type Ia
–
Thermonuclear Destruction of aWhite Dwarf in a Binary System
DEM L71 Kepler’s
SNR
Supernovae Light Curves
C. Strangers in the Night
V838 Mon
R Cygni
V725 SGRType II G11.2-0.3, SN 2006gy Type Ia
DEM L71, Kepler
SU Ursae
Majoris
RY Sagittarii
W Virginis
AH Leo
Flare Stars UV Ceti
X-Ray Binaries GRO J1655, RXJ0806.3+1527
V838 Mon???
?
?
Cosmological DistancesCepheids
The Distance Modulus: M = m -
5log10 (r)
10
Type Ia Supernovae – Standard Candle
Mv
= -19.5
Basic Equations and Relationships
The Distance Modulus: M = m -
5log10
(r)10
Kepler’s
3rd
Law: (MA
+ MB
) = a3
p2
v = d
; a = v
; 2π
a = vP
; Fc
= mac
; ac = v2
= rω2
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
1) Cepheid Light Curve
3) Same Data Plotted Twice
2) Superposition of Periods
4) Same data starting at Maxima
Phase Diagrams
Theory Matches Observation
Perfectly Periodic
Correct EpochCorrect Period
** The slope of each line is the difference between its period and the estimated period.
Perfectly Periodic
Correct Epoch
Wrong Period
**True Period longer
Perfectly Periodic
Change in Period
**True Period Shorterthen Lenthens
Perfectly Periodic
Correct PeriodWrong Epoch
Periodic
Period UnchangedEpoch has Changed
NOT Perfectly Periodic
Different PeriodEach Day
O –
C Diagrams(Observed minus Calculated)
Stellar Evolution –
A Journey with Chandra
Stellar Evolution –
A Journey with Chandra
Stellar Cycles Sets and Cosmic Connections Request URL:http://chandra.harvard.edu/edu/epo/[email protected]
Stellar Cycles Card Set:
Additional Resources:
The American Association of Variable Star Observers
http://www.soinc.org/store/TG-DVD-06v10.htm
UPDATED COACHES MANUAL COMING SOON!!!(AVAILABLE ONLINE AT THE NSO WEBSITE)