m82 as playground for galaxy and star formation
Post on 09-Jan-2016
40 Views
Preview:
DESCRIPTION
TRANSCRIPT
M82 as Playground for Galaxy and Star Formation
Wing-Huen IpInstitute of Astronomy
National Central University
Weihai, August 11, 2005
Outline
•Introduction•Star Formation History – Density Wave vs. SSPSF•M82 – A Prototype of Starburst Galaxy•M82 – Dusty Superwind and H Cap•Disk-Halo Interaction•Massive Coronas of Galaxies•Summary
Learning from BATC
• Juei-Hua Hu: NGC 2168 (Exoplanets/V*)
NGC 381 V*
SLT 20-cm (Exoplanets/V*)• Zhong-Yi Lin: Comets Q2; 9P/Tempel 1 (Deep Impact)• Chia-Hao Hsia: H imaging of PNe (also 2.16 m)
H imaging of nearby galaxies (LOT) to compare
with 2Mass NIR data
NGC 6946
From Yi-Tong Chen
Large-scaled Star Formation Process
• Density Wave Theory: Orbital velocity pattern plus gas density enhancement at spiral arms
• Stochastic Self-Propagating Star Formation: Pressure waves generated by supernovae or massive stars plus differential rotation
Test Cases
• Dwarf galaxies (no spiral arms)
• Starburst galaxies (nuclear regions)
• Both types provide information on star formation and galaxy building processes in early universe (Lyman forests with metal absorption lines -> massive coronas ….)
The Rosette Nebula
30 Doradus in LMC
Henize 70 in LMC
2.3 Elephant Trunk of the Rosette Nebula
LOTKenboo WuNCU
http://amundsen.swarthmore.edu/SHASSA/
Diffuse Ionized Gas (DIG) or Reynold Layer
H emission 11 Kpc above M82Devine and Bally (1999)
Continuous H emission out to11-12 kpc from nuclues until a cap-like structure
Shell-like feature (colliminated super-wind?) with blueshifted speed of50-200 km/s
Formation of bow shock from theexpansion of the superwind?
Question: Any similar structure inother wavelengths (BATC obs.?)
Other Important Obs.
• Very extended soft X-ray emission in good correlation with H emission (kT = 0.87 keV); Lehnert et al., 1999; Stevens et al., 2004
• Shock heating (galactic superwind speed ~ 800 km/s); Lehnert et al., 1999.• Galex obs. of UV halos suggested emissio
n of cold gas and dust (until the H cap); Hoopes et al., 2005.
Massive Coronas of Galaxies
• Dark matter halos contain about 10 times the mass of the visible baryonic matter.
• Mass in the extended corona (r ~ 300 kpc) of a spiral galaxy in ionized hot gas could be much larger than the “condensed” baryons (Fukugita and Peebles, 2005)
• Half coronal hot plasma (kT ~ 0.3 kev) and half dark matter!
• Star fomration rate balanced by plasma condensation rate!
NGC 6946
From Yi-Tong Chen
Summary
Still many puzzles and many challenging issues inspired by M82!
top related