NASA | GSFC | James Webb Space Telescope | 2019 Nov 25
In two separate studies using NASA’s upcoming James Webb Space Telescope, a team of astronomers will observe dwarf galaxy companions to the Milky Way and the nearby Andromeda galaxy. Studying these small companions will help scientists learn about galaxy formation and the properties of dark matter, a mysterious substance thought to account for approximately 85% of the matter in the universe.
- The dwarf galaxy Sculptor, above, is a companion to the Milky Way galaxy. Astronomers will use Webb to study the motions of stars in Sculptor and Draco, another dwarf companion to the Milky Way. By studying how the stars move, the researchers will be able to determine how the dark matter is distributed in these galaxies. Credit: NASA/ESA/Hubble, Digitized Sky Survey 2
In the first study, the team will gain knowledge of dark matter by measuring the motions of stars in two dwarf companions to the Milky Way. In the second study, they will examine the motions of four dwarf galaxies around our nearest large galactic neighbor, the Andromeda galaxy. This will help determine if some of Andromeda’s satellite galaxies orbit inside a flat plane, like the planets around our Sun. If they do, that would have important implications for understanding galaxy formation. The principal investigator for both programs is Roeland van der Marel of the Space Telescope Science Institute (STScI) in Baltimore, Maryland.
Observing Stellar Motions in Dwarf Galaxy Companions to the Milky Way
The nearest galaxies to our own Milky Way are its companion dwarf galaxies, which are much smaller than the Milky Way. Van der Marel and his team plan to study the motions of stars in two of these dwarf galaxies, Draco and Sculptor. The orbits of the stars are governed by the gravity arising from the dark matter in each galaxy. By studying how the stars move, the researchers will be able to determine how the dark matter is distributed in these galaxies. ...
Studying the Motion of Dwarf Galaxy Companions to Andromeda
The nearest large neighbor galaxy of our Milky Way, Andromeda has numerous dwarf galaxy companions, just as the Milky Way does. Van der Marel and his team plan to study how four of those dwarf galaxies are moving around Andromeda, to determine if they are grouped within a flat plane in space, or whether they are moving around Andromeda in all directions.
Unlike the first observation program, the team is not trying to measure how stars inside the dwarf galaxies move. In this study, they are trying to determine how the dwarf galaxies as a whole move around Andromeda. This will provide insights into the process whereby large galaxies form by accretion and accumulation of smaller galaxies, and how exactly that works. ...