Mu Cephei name was known as “Garnet Star” because of it’s deep red color.
Asteroseismology of Gamma Doradus, Beta Cephei, Delta Scuti and other ‘heat-engine’stars
description
Transcript of Asteroseismology of Gamma Doradus, Beta Cephei, Delta Scuti and other ‘heat-engine’stars
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Asteroseismology of Gamma Doradus, Beta Cephei, Delta
Scuti and other ‘heat-engine’stars
Jørgen Christensen-Dalsgaard
Institut for Fysik og Astronomi, Aarhus Universitet
Dansk AsteroSeismologisk Center
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Mode excitation or damping
Growth rate: amplitude / exp( t), with
In nonadiabatic region, L ' constant
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Simplified excitation
Too hot
(J. P. Cox 1964)
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Simplified excitation
Too cold
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Simplified excitation
Just right!!
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Location of instability region
Note: Decreasing Teff ! increasing mb ! increasing for a given opacity bump
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Opacity bumps
Pamyatnykh (1999; Acta Astron. 49, 119)
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Double-mode Cepheids
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! tdyn / (R3/M)1/2
Double-mode Cepheids
! R, M???
Petersen diagram (J.O. Petersen 1973; Astron. Astrophys 27, 89)
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! tdyn / (R3/M)1/2
Track along instability strip
Old opacity
New (OPAL) opacity
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Massive pulsators
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Excitation calculation
Pamyatnykh (1999; Acta Astron. 49, 119)
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Work integralsCephei SPB Scuti
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Asteroseismologi of Ceph stars Eridani
l = 1
l = 1
l = 0
De Ridder et al. (2004; MNRAS 351, 324)
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Models of Eridani
Pamyatnykh et al. (2004; 350, 1022)
Avoided crossings
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Scuti stars
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ExcitationCephei Scuti
Pamyatnykh (2000; ASP. Conf. Ser. 210, 215)
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Excited modesCephei Scuti
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Instability regions
Pamyatnykh (2000; ASP. Conf. Ser. 210, 215)
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Mode selection
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Analysis techniques
Breger (1995; ASP Conf. Ser. 76, 596)
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FG VirginisBreger et al. (2005; Astron. Astrophys. 435, 955)
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FG Virginis frequencies
Breger et al. (2005)
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FG Virginis frequencies
Breger et al. (2005)
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FG Virginis amplitude distribution
Breger et al. (2005)
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FG Virginis frequency interpretationNo rotation
With rotation, nlm = nl0 + m /2
Templeton et al. (2001; ApJ 563, 999)
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Altair: the brightest Scuti star
Buzasi et al. (2005; ApJ 619, 1072)
Observations with the WIRE satellite
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Doradus stars
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Very slow pulsations
Poretti et al. (2002; Astron. Astrophys. 384, 513)
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Very extended observations
Aerts et al. (2004; Astron. Astrophys. 415, 1079)
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Instability region
Warner et al. (2003; ApJ 593, 1049)
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Convective blocking
Guzik et al. (2002; ASP Conf. Ser. 259, 502)