Academic Journal
Gas Dynamics in the Galactic Bar Region
| العنوان: | Gas Dynamics in the Galactic Bar Region |
|---|---|
| المؤلفون: | R. Fux, Fux R |
| المساهمون: | The Pennsylvania State University CiteSeerX Archives |
| المصدر: | http://arxiv.org/pdf/astro-ph/9811384v1.pdf. |
| سنة النشر: | 1998 |
| المجموعة: | CiteSeerX |
| الوصف: | Many early type barred spiral galaxies exhibit strong dustlanes at the leading edges of their bar (e.g. NGC 1300, NGC 1433), which from gas velocity field measurements and numerical hydrodynamical simulations are known to be the loci of shearing shocks with velocity gaps up to 200 kms −1 across. As an SBbc type galaxy, the Milky Way is expected to present similar dustlanes. Selfconsistent high resolution 3D N-body and SPH simulations allow us to reliably identify their gaseous traces in the Galactic CO and HI ℓ −V distributions. The near-side branch of these dustlanes corresponds to the connecting arm feature and lies below (b < 0) the Galactic plane, while the far side branch, seen nearly end-on, traces a velocity-elongated feature near ℓ = −4 ◦ and is located above the plane. The 3-kpc and 135-km s −1 arms are lateral arms, i.e. inner prolongations of disc spiral arms passing round the bar and finally intersecting the dustlanes at their respective latitudes (Figs. 1a-b). Considering that the latter intersections occur close to the major axis of the bar and within the bar ends, their spatial location can provide new constraints on the inclination angle ϕ and corotation radius RCR of the Galactic bar. Geometrically, if ℓ1 and ℓ2 are the longitudes where the 3-kpc and the 135-km s −1 arms respectively intersect the dustlanes, and s1 and s2 the galactocentric distances of these intersections (Fig. 1c), then: si R◦ sin ℓi sin(ϕ + ℓi) 1 + q (i = 1, 2), ϕ = − cot ℓ2 + q cot ℓ1 where q ≡ s1/s2 is an unknown asymmetry parameter. The 135-km s −1 arm indeed involves higher forbidden velocities than the 3-kpc arm which, according to our models, means that the former arm is closer to the Galactic centre than the latter, i.e. q> 1. The CO observations suggest ℓ1 = 14.5 ◦ and ℓ2 = −4.5 ◦, yielding the constraints shown in Fig. 1d. The length s1 increases for smaller inclination angles. If ϕ ≤ 30 ◦ , then s1 ≥ 2.9 kpc, q ≤ 2 and, since s1 < a and RCR ≈ 1.2a according to numerical simulations and early type galaxy ... |
| نوع الوثيقة: | text |
| وصف الملف: | application/pdf |
| اللغة: | English |
| Relation: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.255.9036; http://arxiv.org/pdf/astro-ph/9811384v1.pdf |
| الاتاحة: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.255.9036 http://arxiv.org/pdf/astro-ph/9811384v1.pdf |
| Rights: | Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
| رقم الانضمام: | edsbas.50D2E8F3 |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |