These three chief components of the Milky Way are thought to have formed at different times, with the halo taking shape first. The oldest globular clusters in our galaxy are 13.5 billion years old, meaning they formed just 200 million years or so after the Big Bang that created the universe...
The Milky Way is a barred spiral galaxy with a visible diameter between 150,000 and 200,000 light-years. It is estimated to contain 100-400 billion stars and at least that number of planets. The dark matter halo around the Milky Way may span as much as 2 million light years. The ...
The Milky Way galaxy has several components, such as the bulge, disk and halo. Unravelling the assembly history of these stellar populations is often restricted because of difficulties in measuring accurate ages for low-mass, hydrogen-burning stars. Unlike these progenitors, white dwarf stars, the...
Milky Way Galaxy- the galaxy containing the solar system; consists of millions of stars that can be seen as a diffuse band of light stretching across the night sky Milky Way,Milky Way System extragalactic nebula,galaxy- (astronomy) a collection of star systems; any of the billions of systems...
The Milky Way’s stellar halo is the visible portion of what is more broadly called the galactic halo. This galactic halo is dominated by invisible dark matter, whose presence is only measurable through the gravity that it exerts. Every galaxy has its own halo of dark matter. These halos se...
[29] As the orbital velocity depends on the total mass inside the orbital radius, this suggests that the Milky Way is more massive, roughly equaling the mass of Andromeda Galaxy at 7×1011 M☉ within 69 of its center.[30] A 2010 measurement of the radial velocity of halo stars finds ...
it became clear that the mix of populations in galaxies was correlated with Hubble type.Spiral galaxiessuch as the Milky Way Galaxy have Population I concentrated in the spiral disk and Population II spread out in a thick disk and/or a spherical halo.Elliptical galaxiesare nearly pure Population...
The least-understood component of the Galaxy is the giant massive halo that is exterior to the entire visible part. The existence of the massive halo is demonstrated by its effect on the outer rotation curve of the Galaxy (see belowMass). All that can be said with any certainty is that ...
The evolution of the Milky Way began when clouds of gas and dust started collapsing, pushed together bygravity. First stars sprung up from the collapsed clouds, those that we see today in the globular clusters. The spherical halo emerged soon after, followed by the flat galactic disk. The g...
Astronomers at the University of Michigan's College of Literature, Science, and the Arts (LSA) discovered for the first time that the hot gas in the halo of the Milky Way galaxy is spinning in the same direction and at comparable speed as the galaxy's disk, which contains our stars, pla...