High resolution observations of the Galactic Center at radio wavelengths have revealed a complex structure of ionized gas called the 'mini-spiral'. The mini-spiral is broken down into individual components including the Northern Arm, Western Arc and Eastern Arm (see below). The mini-spiral is surrounded by a thick ring of molecular material called the Circumnuclear Disk (CND) which is from 2.5 to 4.8 parsecs (50 to 95 arcseconds) in size with an inferred inclination of 60 degrees assuming a circular structure (Gusten et al 1987). It is primarily seen in radio molecular emission from carbon monoxide (CO) or hydrogen cyanide (HCN) molecules.
The motion of the gas comprising the mini-spiral is determined using the Doppler shift of emission lines including the NeII and Bracket gamma hydrogen lines. These studies show that the gas along the Nothern Arm is falling in toward or orbiting around Sgr A*. There are many ideas about the origin of the mini-spiral. Some believe that the it is created by the same type of gravitational perturbation which forms the pretty pattern observed in spiral galaxies. One theory explaining the motion of the gas in the mini-spiral suggests the gas is in a Keplerian orbit around the supermassive black hole. The other interpretation is that the gas is not bound to the galactic center and therefore is on a hyperbolic orbit. Another scenario for the formation of the mini-spiral involves the collision of gas cloudlets within the CND which causes the clouds the lose angular momentum and fall in towards Sgr A*. Indeed the CND appears to have a clumpy structure and the ionized filaments along the mini-spiral are coincident with the inner edge of the CND and appear to terminate in the CND which, in turn, has an impression at the termination point. The CND is not believed to be in dynamical equilibrium meaning that if cloud collisions within the CND are responsible for creating the mini-spiral then material must be provided to replenish the CND. Some of the material could be coming from a nearby Giant Molecular Cloud (GMC) called the "20 km/s cloud".
-------------------------------------------------------------------------------------------------------------
60 degree
The motion of the gas comprising the mini-spiral is determined using the Doppler shift of emission lines including the NeII and Bracket gamma hydrogen lines. These studies show that the gas along the Nothern Arm is falling in toward or orbiting around Sgr A*. There are many ideas about the origin of the mini-spiral. Some believe that the it is created by the same type of gravitational perturbation which forms the pretty pattern observed in spiral galaxies. One theory explaining the motion of the gas in the mini-spiral suggests the gas is in a Keplerian orbit around the supermassive black hole. The other interpretation is that the gas is not bound to the galactic center and therefore is on a hyperbolic orbit. Another scenario for the formation of the mini-spiral involves the collision of gas cloudlets within the CND which causes the clouds the lose angular momentum and fall in towards Sgr A*. Indeed the CND appears to have a clumpy structure and the ionized filaments along the mini-spiral are coincident with the inner edge of the CND and appear to terminate in the CND which, in turn, has an impression at the termination point. The CND is not believed to be in dynamical equilibrium meaning that if cloud collisions within the CND are responsible for creating the mini-spiral then material must be provided to replenish the CND. Some of the material could be coming from a nearby Giant Molecular Cloud (GMC) called the "20 km/s cloud".
-------------------------------------------------------------------------------------------------------------
60 degree
So what’s the problem? Well, if the solar wind was completely gone, galactic cosmic rays should be streaming in from all directions. Instead, Voyager found them coming preferentially from one direction. Furthermore, even though the solar particles had dropped off, the probe hasn’t measured any real change in the magnetic fields around it. That's hard to explain because the galaxy’s magnetic field is thought to be inclined 60 degrees from the sun’s field.
-----------------------------------------------------
Does our solar system rotate parallel or perpendicular to the galactic disc?
Neither. You have created a false dilemma. There are lots and lots of other possibilities; in fact, there are an uncountably infinite number of other possibilities. The ecliptic plane is inclined at about a 60 degree angle with respect to the galactic plane. With the possible exception of systems fairly close to the galactic core, the orientation of planetary systems with respect to the galaxy is more or less random.
-----------------------------------------------------------
Assuming our solar system is at a 60degree angle in respect to the galactic plane, the planets would still not trail behind the sun like they do in the video. The theory of relativity(as well as our observation of the planets in our solar system) show that the sun's gravity acting on the planets are enough to form a flat plane. If you want to know why things usually flatten out google that, but the short explanation is that no matter what the original conditions are, collisions/gravity will spin the objects into more of a disk formation. This is why we don't see spherical galaxies, and why the majority of our solar system is relatively flat, or on a much smaller scale why the rings around Saturn are so flat. The speed of the solar system going through the galaxy would not cause the planets to trail behind because masses that are in orbit aren't just trailing along holding on by a
thread they are bound rather strongly.
----------------------
Does our solar system rotate parallel or perpendicular to the direction of the expansion of the universe?The answer is neither. There is no "direction" to the universe's expansion. In technical terms, it is simply a real valued, time varying parameter - the so called "scale factor" - in the FLRW metric.In practical terms, a lower dimensional mind picture might help you. Imagine a rubber 2-sphere as a model for a two spatial dimension universe, and we draw little pictures on the outside: we'll make them look like galaxies if you like. In particular, draw a straight line segment on the surface. Then we blow the sphere slowly up by pumping air into it. Now, what is the direction of the expansion relative to the line segment's direction? If the expansion is isotropic and the sphere just becomes an every swelling bigger sphere, the proper distances between pairs of points joined by a line segment in any direction increases at the same rate. The expansion is uniform and has no preferred direction.
கருத்துகள் இல்லை:
கருத்துரையிடுக