J Leon Wilde BGSU March 31 st 2005
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Transcript of J Leon Wilde BGSU March 31 st 2005
J Leon Wilde
BGSU
March 31st 2005
Pulsating Variable StarsWelcome
Pulsating Variable StarsOverview
• History of discovery
• What are pulsating variable stars?
• Why are they important?
• Any recent works?
Pulsating Variable StarsHistory
• 1595 – David Fabricius– o Ceti, 11 months
• 1784 – John Goodricke– d Cephei, 5d, 8h, 48min
• ~1912 – Henrietta Leavitt
Pulsating Variable StarsHistory
Pulsating Variable StarsPVS Physics
• Periodic luminosity changes• Radial vs Nonradial• Pressure wave estimation:
Pulsating Variable StarsPVS Physics
Pulsating Variable StarsPVS Physics
• Classes:
Pulsating Variable StarsWho cares?
• Very large luminosities• Distance calibrations
Pulsating Variable StarsRecent work?
• Polaris!• Period
– 1844-2004, increase 4.5s/year– 1963-1966, brief hiatus
• Magnitude– Prior to 1963, 0.1mag– After 1966, sharp decline, 0.05mag
• Seems to no longer pulsate
Pulsating Variable StarsThanks and references
• Thanks!• References:
– http://www.adsabs.harvard.edu/– http://zebu.uoregon.edu/~soper/MilkyWay/cepheid.html– http://www.cartage.org.lb/en/themes/Sciences/Astronomy/
Thestars/energyproduct/EnergyTransport/EnergyTransport.htm– http://antwrp.gsfc.nasa.gov/apod/ap981027.html– http://astro.wsu.edu/worthey/astro/html/lec-women.html– http://www.if.ufrgs.br/oei/stars/aglom/clusters.htm– Polaris article:
http://www.journals.uchicago.edu/PASP/journal/issues/v117n828/205015/205015.html
• Powerpoint presentation available @:http://www.wildealien.com/astro/vst.ppt