4/19/2010
Extragalactic Planetary Nebulae: One of the Universe’s Swiss Army Knives
John Feldmeier Case Western Reserve University
Collaborators: Robin Ciardullo (PSU), George Jacoby (WIYN Observatory), Pat Durrell (PSU), Chris Mihos (CWRU), Kara Krelove (ASU), Rachel Kuzio-de Naray (Maryland)
M57 – aka the “Ring” Nebula
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History of Planetary Nebulae (PN)
• First discovered in 1764 by Charles Messier • Given their (inaccurate) name by William Herschel shortly thereafter leading to centuries of problems for innocent astronomers • First spectra taken by William Huggins in 1864
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How do we explain Nebulium? - 1
• Russell (1927) speculated that such lines came from “metastable states” which are collisionally de-excited before they can emit on Earth. • Bowen (1928, 1935) realized that the 5007 and 4959 Angstrom lines were emitted by doubly ionized Oxygen.
15% of the total energy of the nebula are emitted in these lines!
How do we explain Nebulium? - 2
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Planetary Nebulae are dying Stars
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Feldmeier, Ciardullo, & Jacoby (1996)
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M101 – The Pinwheel
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The Planetary Nebulae Luminosity Function (PNLF) does not depend on:
•Galaxy Type •Stellar Population Age •Dust properties
Distance to M101 = 7.7 +/- 0.7 Mpc
Feldmeier, Ciardullo & Jacoby (1997)
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M51 – The Whirlpool
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Discovery of a new galaxy in front of M31!!
Work done by Heather Morrison, Paul Harding, Denise Hurley-Keller (CWRU) and George Jacoby (WIYN)
Galaxy has 100 – 200 billion solar masses, and is being torn apart by M31!
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PN can be found outside of galaxies too!
Virgo Cluster results (15 Mpc)
318 IPN candidates in 0.8% of Virgo (Feldmeier, Ciardullo, Jacoby 1998; Feldmeier et al. 2003; Feldmeier et al. 2004)
About 30 spectroscopically identified (Freeman et al. 2000; Arnaboldi et al 2003)
Result: 15.8% +/- 5% of all stars in the Virgo cluster are intracluster
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Fornax Cluster (D = 17 Mpc) - 138 IPN candidates here.
20% +/- 5% of the starlight is intracluster in nature
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Conclusions
Planetary Nebulae can be used: • To learn about physics of diffuse gas • To obtain distances to nearby galaxies, and determine the Hubble Constant • To measure velocities of stars in interacting or disrupting galaxies • To find large numbers of unseen stars in nearby galaxy clusters
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