LIFECYCLES OF STARS
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M.A.Burleigh 2601/Unit 6 DEPARTMENT OF PHYSICS AND ASTRONOMY LIFECYCLES OF STARS LIFECYCLES OF STARS Option 2601 Option 2601
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LIFECYCLES OF STARS. Option 2601. Stellar Physics. Unit 1 - Observational properties of stars Unit 2 - Stellar Spectra Unit 3 - The Sun Unit 4 - Stellar Structure Unit 5 - Stellar Evolution Unit 6 - Stars of particular interest. Unit 6. Particularly Interesting Stars. - PowerPoint PPT Presentation
Transcript of LIFECYCLES OF STARS
M.A.Burleigh 2601/Unit 6
DEPARTMENT OF PHYSICS AND ASTRONOMY
LIFECYCLES OF STARSLIFECYCLES OF STARS
Option 2601Option 2601
M.R. Burleigh 2601/Unit 6
Stellar PhysicsStellar Physics
Unit 1 - Observational properties of Unit 1 - Observational properties of starsstars
Unit 2 - Stellar SpectraUnit 2 - Stellar Spectra Unit 3 - The SunUnit 3 - The Sun Unit 4 - Stellar StructureUnit 4 - Stellar Structure Unit 5 - Stellar EvolutionUnit 5 - Stellar Evolution Unit 6 - Stars of particular interestUnit 6 - Stars of particular interest
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DEPARTMENT OF PHYSICS AND ASTRONOMY
Unit 6Unit 6
Particularly Interesting StarsParticularly Interesting Stars
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Particularly Interesting StarsParticularly Interesting Stars
Binaries – visual, spectroscopic, Binaries – visual, spectroscopic, eclipsingeclipsing
Variable starsVariable stars Active/interacting binaries (Novae)Active/interacting binaries (Novae) Stellar pulsationsStellar pulsations Cepheid variables and the distance Cepheid variables and the distance
scalescale
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ApparentApparent Stars not physically associated but lie Stars not physically associated but lie close together along the line of sightclose together along the line of sight
VisualVisual Stars can be resolvedStars can be resolved
AstrometricAstrometric Only one star visible but its motion on Only one star visible but its motion on the sky reveals an unseen companionthe sky reveals an unseen companion
SpectroscopicSpectroscopic Unresolved system, see periodic Unresolved system, see periodic shifts/broadening of spectral linesshifts/broadening of spectral lines
SpectrumSpectrum No movement of spectral features but No movement of spectral features but two different spectral signatures two different spectral signatures visiblevisible
EclipsingEclipsing Brightness changes as one star Brightness changes as one star passes in front of the otherpasses in front of the other
Types of binary systemTypes of binary system
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Spectroscopic BinariesSpectroscopic Binaries
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Eclipsing BinariesEclipsing Binaries
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Eclipsing BinariesEclipsing Binaries
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Information from Binary SystemsInformation from Binary Systems
Masses of componentsMasses of components Dimensions of components (particularly Dimensions of components (particularly
in eclipsing systems)in eclipsing systems) Physical characteristics of systemsPhysical characteristics of systems
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(Other) Variable Stars(Other) Variable Stars
Intrinsic variables… i.e. pulsating starsIntrinsic variables… i.e. pulsating stars Geometric (extrinsic) variables… i.e. Geometric (extrinsic) variables… i.e.
eclipsing systemseclipsing systems Naming variables… constellation & Naming variables… constellation &
letters beginning with Rletters beginning with R– R…. To Z, then RR…. To ZZ (i.e. R CrB)R…. To Z, then RR…. To ZZ (i.e. R CrB)– Then Vijk constellation (i.e. V471 Tau)Then Vijk constellation (i.e. V471 Tau)
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Accretion in BinariesAccretion in Binaries
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NovaeNovae
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NovaeNovae
Brightness increases by 10 magnitudes Brightness increases by 10 magnitudes during outburstduring outburst
Rise time 2-3 daysRise time 2-3 days Gradual decline over months (fast Gradual decline over months (fast
novae) or years (slow novae)novae) or years (slow novae) Material ejected with velocities up to Material ejected with velocities up to
~2000km s~2000km s-1-1
Explosions can repeat (recurrent novae)Explosions can repeat (recurrent novae)
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Nova Cassiopeiae 1993 light curve (first 3 months)
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Nova Cassiopeiae 1993 light curve (first 2½ years)
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Nova Cassiopeiae 1995 light curve
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Pulsating StarsPulsating Stars
Pulsating stars are not in hydrostatic Pulsating stars are not in hydrostatic equilibriumequilibrium
Star is partially ionized at some critical Star is partially ionized at some critical depthdepth
Degree of ionization sensitive to small Degree of ionization sensitive to small temperature changestemperature changes
Small perturbation can be “amplified”Small perturbation can be “amplified”
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Phase
MAX. COMPRESSION
Max. opacity & ionisation, min.
photon fluxEXPANSION
Max. expansion
rate
COMPRESSION
Max. compression
rate
MAX. EXPANSION
Min. opacity & ionisation, max.
photon flux
Pressure driving
Gravity (restoring
force)
Cycle of a pulsating star
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TypeType PrototypePrototype MMVV Spectral Spectral classclass
Pulsation Pulsation period period rangerange
CharacterisCharacteristic periodtic period
PopulationPopulation
Classical Classical CepheidsCepheids
CepheiCephei -0.5 to –6-0.5 to –6 F6 to K2F6 to K2 11dd to 50 to 50dd 55dd to 10 to 10dd II
Population Population II Cepheids II Cepheids (W Virginis)(W Virginis)
W VirginisW Virginis 0 to –30 to –3 F2 to G6F2 to G6 22dd to 45 to 45dd 1212dd to 28 to 28dd IIII
RR Lyrae RR Lyrae starsstars
RR LyraeRR Lyrae 0.5 to 10.5 to 1 A2 to F6A2 to F6 1.51.5hh to 24 to 24hh 0.50.5dd IIII
Long-period Long-period variables variables (Mira)(Mira)
CetiCeti 1 to –21 to –2 M1 to M6M1 to M6 130130dd to 500 to 500dd 270270dd DiskDisk
RV Tauri RV Tauri starsstars
RV TauriRV Tauri -3-3 G, KG, K 2020dd to 150 to 150dd 7575dd IIII
Beta Canis Beta Canis Majoris Majoris starsstars
Canis Canis MajorisMajoris
-3-3 B1, B2B1, B2 44hh to 6 to 6hh 55hh II
Semiregular Semiregular red red variablesvariables
HerculisHerculis -1 to –3-1 to –3 K, M, R, N, K, M, R, N, SS
100100dd to 200 to 200dd 100100dd I and III and II
Dwarf Dwarf CepheidsCepheids
ScutiScuti 4 to 24 to 2 A to FA to F 11hh to 3 to 3hh 22hh II
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H-R diagram for pulsating starsH-R diagram for pulsating stars
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Typical Cepheid light curve
Cepheid VariablesCepheid Variables
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Cepheid VariablesCepheid Variables
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Cepheid VariablesCepheid Variables
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The period-luminosity relation for Cepheids
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RedshiftRedshift
Edwin Hubble discovers galaxies are Edwin Hubble discovers galaxies are receding from us (c. 1930)receding from us (c. 1930)
Hubbles Law - speed increases with Hubbles Law - speed increases with distancedistance
Expansion of the Universe - Big Bang Expansion of the Universe - Big Bang theorytheory
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Cepheids in M100Cepheids in M100
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Beyond M100Beyond M100
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DEPARTMENT OF PHYSICS AND ASTRONOMY
Unit 6Unit 6
Particularly Interesting StarsParticularly Interesting Stars
M.R. Burleigh 2601/Unit 6
Particularly Interesting StarsParticularly Interesting Stars
Binaries – visual, spectroscopic, Binaries – visual, spectroscopic, eclipsingeclipsing
Variable starsVariable stars Active/interacting binariesActive/interacting binaries Stellar pulsationsStellar pulsations Cepheid variables and the distance Cepheid variables and the distance
scalescale
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Stellar PhysicsStellar Physics
Unit 1 - Observational properties of Unit 1 - Observational properties of starsstars
Unit 2 - Stellar SpectraUnit 2 - Stellar Spectra Unit 3 - The SunUnit 3 - The Sun Unit 4 - Stellar StructureUnit 4 - Stellar Structure Unit 5 - Stellar EvolutionUnit 5 - Stellar Evolution Unit 6 - Stars of particular interestUnit 6 - Stars of particular interest
M.A.Burleigh 2601/Unit 6
DEPARTMENT OF PHYSICS AND ASTRONOMY
LIFECYCLES OF STARSLIFECYCLES OF STARS
Option 2601Option 2601
