Department of Physics and Astronomy Rice University Evolving Ideas About HH Objects Patrick Hartigan Stromfest April 4, 2008 History • The Reflection Nebula Hypothesis • Subsequent Development of Field New Stuff • Conditions near the Star • MHD far from the star
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Department of Physics and Astronomy Rice University
Department of Physics and Astronomy Rice University. Stromfest April 4, 2008. Patrick Hartigan. History The Reflection Nebula Hypothesis Subsequent Development of Field. Evolving Ideas About HH Objects. New Stuff Conditions near the Star MHD far from the star. DISCOVERY!. - PowerPoint PPT Presentation
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Department of Physics and Astronomy
Rice University
Evolving Ideas About HH Objects
Patrick Hartigan Stromfest April 4, 2008
History• The Reflection Nebula Hypothesis• Subsequent Development of Field
New Stuff• Conditions near the Star• MHD far from the star
Herbig 1951, ApJ 113 697
Haro 1952, ApJ 115 572
Ambarzumian, 1954 Comm. Burakan Obs No 13Argues these are related to young stars – coins term HH object
DISCOVERY!
Emission lines… Photoionized… but where is the blue star?
What Causes the Emission Lines?
1956 ApJ 123 379
High ionization, low temperature:“The most obvious means of explaining the ionization is to
assume a strong radiation field in the far-ultraviolet”
HH Objects as Reflection Nebulae ApJ 191, 111, 1974
They are polarized! ApJ 191, L93, 1974
But Wait, Emission Lines Unpolarized ApJ 234, L191, 1979
What went wrong?
Examples can be more complex:
Hartigan et al 1999
What went right?
• Model made TESTABLE PREDICTIONS (i.e. it could be proved wrong)
• Motivated future work
• There are reflection nebulae in these objects
• HH Objects are displaced from host stars
• HH Objects are usually not photoionized nebulae
Spectra, Supersonic Velocities Imply Shocks Schwartz 1975Large Linewidths Imply Bow Shocks Schwartz 1978Proper Motions Imply “Bullets” Herbig and Jones 1981UV Spectra Confirm Shocks Bohm et al 1981 Ortolani and D’Odorico 1980