What does a galactic rotation curve show?
The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy’s centre. Stars revolve around their galaxy’s centre at equal or increasing speed over a large range of distances.
How does dark matter explain galactic rotation curves?
One point of evidence in support of dark matter is the way in which the speed of stars, gas and dust in a galaxy varies with their distance from the center of the galaxy, known as the galactic rotation curve. The orbital speed of stars in a galaxy depends upon the gravitational pull of a galaxies mass.
Why rotation curves in galaxies are flat at distances far from the center of the galaxy?
3. Rotation curves of galaxies are flat. The velocities of objects (stars or gas) orbiting the centers of galaxies, rather than decreasing as a function of the distance from the galactic centers as had been expected, remain constant out to very large radii.
What does the rotation curve allow to be measured?
Once the rotation curve for the Galaxy is known, it can be used to find the distances to various objects. By knowing the Doppler shift of a body, its angular velocity can be calculated. Combining this angular velocity and the plot of the rotation curve, the distance to a certain object can be inferred.
What did Vera Rubin observe?
Astronomer Vera Rubin changed the way we think of the universe by showing that galaxies are mostly dark matter. On a dry and clear night at the Kitt Peak Observatory in the mountains of southern Arizona, Rubin closely observed the spectra of stars in the Andromeda Galaxy to determine their velocities.
Does dark matter rotate?
A flat rotation curve is consistent with a roughly spherical distribution of dark matter with a flat core in a galaxy.
Is gravitational lensing real?
This is called gravitational lensing. Strong gravitational lensing can actually result in such strongly bent light that multiple images of the light-emitting galaxy are formed. Weak gravitational lensing results in galaxies appearing distorted, stretched or magnified.
What is the universe’s age?
The universe is (nearly) 14 billion years old, astronomers confirm. With looming discrepancies about the true age of the universe, scientists have taken a fresh look at the observable (expanding) universe and have estimated that it is 13.77 billion years old (plus or minus 40 million years).
Does dark matter cause gravitational lensing?
Dark matter is an invisible form of matter that makes up most of the universe’s mass and creates its underlying structure. Dark matter’s gravity drives normal matter (gas and dust) to collect and build up into stars and galaxies. This phenomenon is called gravitational lensing.
Why do we call dark matter dark?
Dark matter is called dark because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect or emit electromagnetic radiation, and is therefore difficult to detect.
Did Rubin believe in dark matter?
Her data showed that stars at the edges of multiple galaxies were moving in ways that didn’t make sense, according to the rules of physics. One possible explanation for this strange phenomenon, Rubin suggested, was the existence of a mysterious “dark matter” at the edges of the galaxy.
How did Vera Rubin prove dark matter?
In the 1960s and ’70s, Rubin’s observations of stars whirling around within galaxies revealed the gravitational tug of invisible “dark matter.” Although astronomers had detected hints of this enigmatic substance for decades, Rubin’s data helped finally convince a skeptical scientific community that dark matter exists ( …
How does the rotation of a galaxy support dark matter?
One point of evidence in support of dark matter is the way in which the speed of stars, gas and dust in a galaxy varies with their distance from the center of the galaxy, known as the galactic rotation curve.
What is the rotation curve of a disc galaxy?
The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy’s centre. It is typically rendered graphically as a plot, and the data observed from each side of a spiral galaxy are generally asymmetric,…
Is the rotation of the Triangulum Galaxy wrong?
But new research on galactic rotation curves has found an odd correlation, and it could mean that dark matter is wrong after all. The rotation curve for M33, also known as the Triangulum galaxy. Credit: Wikipedia
How can you predict the rotation of a spiral galaxy?
A consistent way to predict the rotational velocity of a spiral galaxy is to measure its bolometric luminosity and then read its rotation rate from its location on the Tully–Fisher diagram. Conversely, knowing the rotational velocity of a spiral galaxy gives its luminosity.