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