Gas Flow Induced by a Strong Bar Potential: Straight Dust Lanes Connecting to a Nuclear

Starburst Ring

David YenDepartment of Mathematics, Fu-Jen Catholic University, Taiwan,

R.O.C.

Lien-Hsuan Lin Department of Physics, National Taiwan University, Taiwan, R.O.C

Chi YuanInstitute of Astronomy and Astrophysics, Academia Sinica,

Taiwan, R.O.C.

Chao-Chin YangDepartment of Astronomy, UIUC

2006,November 1, KASI, Korea

Outline

•NGC1300

•NGC6782

•Comparison with observation

•Gas Flow

•Conclusion

NGC1300

1. Major bar

2. Central ring

3. Straight dust lane

4. Enhance SF at the end of bar

NGC1300 has a central star formation ring and a pair of straight dust lanes.

How does the straight dust lane form?

How about the location of resonance?

p

OLR : outer Lindblad resonanceOILR : outer-inner Lindblad resonance

IILR : inner-inner Lindblad resonance

Lindblad Resonance

Profile

2

2

OILR=8.62kpckpcskmp /1.4

Location of Lindblad Resonance ( NGC1300)

Other effects?

Grid size : 256X256

Ratio of the bar force :1 : 2 : 3 : 3.75 : 4

Effects of the strength of Bar forces

Size of nucleus ring

Straight dust line

Strong bar for NGC1300? Yes!

NGC1300

Comparison with

observations

NGC6782

4050A

NGC6782 has diamond shape double rings.

(km/s)0.01

223.943r+

r=v

kpc15.3

kpc8.9

kpc2.6

km/s/kpc25

=R

=R

=R

=Ω

OLR

CR

ILR

p

Location of Lindblad Resonance ( NGC6782)

Projected with I.A. = 26P.A. = 177P.A.disk = 45

Comparison with

observations

Comparison with

observations

(in rotating frame)Gas Flow

(in rotating frame)Gas Flow

(in rotating frame)

we can see gas flow suddenly changes its direction upon entering the dust lanes, which are known as shocks, and continues to flow down the dust lanes along the leading edge of the bar.

Gas Flow

(in rotating frame)Gas Flow

(in rotating frame)Gas Flow

Conclusion• Our simulations can reproduce dust lanes, central

starburst rings and outer spirals, exact as seen in the nearby barred galaxies.

• NGC1300 is a major bar galaxy, our simulation produced straight lanes and star formation region located at the end of the bar which match the observations well.

• Our results is in excellent agreement with the diamond-shape which generated by the interaction of OLR and ILR for NGC6782.

• Strong bar potentials may lead to shear instability and develop chaotic sub-structures.

• Gas flow suddenly changes its direction upon entering the dust lanes, which are known as shocks, and continues to flow down the dust lanes along the leading edge of the bar.