Galactic Center - Wikipedia
Why do the halo stars have such different orbits than the disk stars?
Halo stars have different orbits, so when they pass through the disk they have high speeds relative to the nearby disk stars.) What evidence suggests that most of the mass of the Milky Way is in the form of dark matter? The orbital speeds of stars far from the galactic center are surprisingly high.
Why are stars no longer forming in the galactic halo?
Why has star formation ceased in the galactic halo? All of the galaxy’s cool gas settled to the galactic plane long ago.
How do stars orbit in the halo?
Stars in the inner halo have highly radial orbits, plunging toward the galactic center and traveling back out again. When the team compared the tangential motion of the outer halo stars with their radial motion, they were very surprised to find that the two were equal.
Why are halo stars older than disk stars?
The ages of stars suggest that the bulge and halo of the Milky Way formed before many of the stars in the disk. Which would you expect to have more heavy metals (a.k.a. higher metallicity)? The ages of stars suggest that the bulge and halo of the Milky Way formed before many of the stars in the disk.
Are halo stars older than disk stars?
Now the Hubble Space Telescope has found that an individual halo star is even older than these ancient star cities and is thus an ideal time capsule passed down from the Milky Way’s birth.
How do we know that halo stars are older on average than disk stars?
How do we know that the halo stars are older, on average, than disk stars? A) We see evidence for new stars forming in the disk today. B) Theories of galaxy formation tell us that the halo formed earlier than the disk.
Why do disk stars bob up and down?
Why do orbits of bulge stars bob up and down? They’re stuck to the interstellar medium. Gravity of disk stars pulls toward disk. Halo stars knock them back into disk.
Whats the difference between the galactic bulge and the galactic disk?
Unlike the disk, the distribution of stars in the galactic bulge is not exponential. It was once thought to be spheroidal, with an effective radius – the radius which contains half the light – of a few kpc. However, recent results indicate that the bulge is not spheroidal, but is more likely bar shaped.
Is the Sun a disk or halo star?
Stars in the disk (the Sun, for instance) are fairly rich in heavy elements. This indicates that they are young stars, made from recycled gas into which planetary nebulae and supernovae have dumped heavy elements (carbon, oxygen, iron, and so forth).
How far do halos extend?
In the Milky Way the dark halo appears to extend out to at least 300,000 light years, and possibly even further, reaching far beyond the extent of the visible matter in the disk.
What are galactic halos made of?
galactic halo, in astronomy, nearly spherical volume of thinly scattered stars, globular clusters of stars, and tenuous gas observed surrounding spiral galaxies, including the Milky Way—the galaxy in which the Earth is located.
How many stars are in the galactic halo?
The researchers measured 1,301 stars located at the vast distances of the halo, using data from the European Space Agency’s Gaia mission and NASA’s Near Earth Object Wide Field Infrared Survey Explorer (NEOWISE, which also gave name to the comet of 2020).
Do stars form in the halo?
The halo is home to some ancient star clusters, known as globular clusters. They are known to be old because their stars contain low levels of heavy elements, which weren’t present in the young universe and were built up over time in supernovae. The clusters move about the galactic nucleus in (nearly) random orbits.
How do stars in the disk of the Milky Way move?
Most galaxies, including our own Milky Way, are spiral-shaped and stars are distributed in a thin disk rotating around the galactic center, with areas divided into spiral arms or elliptical regions such as the central bar. Due to gravity, the spiral arms move through the disk in the form of density waves.
What kinds of objects lie in the halo of a spiral galaxy?
The Milky Way’s stellar halo contains globular clusters, RR Lyrae stars with low metal content, and subdwarfs. Stars in our stellar halo tend to be old (most are greater than 12 billion years old) and metal-poor, but there are also halo star clusters with observed metal content similar to disk stars.
Why do stars in the halo of the galaxy have almost no heavy elements?
Why do stars in the halo of the galaxy have almost no heavy elements such as carbon, nitrogen, and oxygen? Halo stars formed before those elements were made. Where do stars form in the galaxy today?
What is not found in the halo of our galaxy?
Open clusters and young stars are generally found only in the disk of the galaxy and not in the halo. We can see most of the galaxy with visible light. Observing the galaxy at radio wavelengths allows us to see beyond the dust in the disk of the galaxy that obscures our view.
Which of the following provides the strongest evidence that halo stars are older?
Which of the following provides the strongest evidence that halo stars are older, on average, than disk stars? Theories of galaxy formation tell us that the halo formed earlier than the disk.
Why do we expect WIMPs to be distributed throughout galactic halos rather than settled into the galaxy’s disk?
Why do we expect WIMPs to be distributed throughout galactic halos, rather than settled into a disk? Since they do not interact with the electromagnetic force, they do not feel friction or drag and hence do not contract with the rest of the protogalactic cloud.
Which of the following best describes how disk stars orbit in a galaxy?
The disk stars have nearly circular orbits. They have vertical motions out of the plane, making them appear to bob up and down, but they never get “too far” from the disk.
What black hole is at the center of our galaxy?
In 2019, the Event Horizon Telescope team released the first image of a black hole — this one at the center of the galaxy M87. The black hole at the center of this galaxy, named M87*, is a behemoth 2,000 times larger than Sagittarius A* and 7 billion times the mass of the sun.
Which of the following statements correctly summarize key differences between the disk and the halo check all that apply?
Which of the following statements correctly summarize key differences between the disk and the halo? Stars in the disk all orbit in the same direction and nearly the same plane, while halo stars have more randomly oriented orbits.
Is the bulge inside the halo?
Bulges are generally concentrated in the central regions of galaxies, while halos typically follow a diffuse distribution that extends from the center to an extended envelope.
What is the disk bulge and halo of our galaxy?
The halo – a roughly spherical distribution which contains the oldest stars in the Galaxy, The nuclear bulge and Galactic Center. The disk, which contains the majority of the stars, including the sun, and virtually all of the gas and dust.
Are halo stars older than disk stars?
Halo stars formed first, then stopped! Disk stars formed later, kept forming! How Did Our Galaxy Form? Our galaxy probably formed from a giant gas cloud!