apogee tagged posts

Physicists discovered stars near the edge of the Milky Way travel more slowly than those closer to its center — a surprise suggesting our galaxy’s gravitational core may have less dark matter than previously thought.

By clocking the speed of stars throughout the Milky Way galaxy, MIT physicists have found that stars further out in the galactic disk are traveling more slowly than expected compared to stars that are closer to the galaxy’s center. The findings raise a surprising possibility: The Milky Way’s gravitational core may be lighter in mass, and contain less dark matter, than previously thought.

The new results are based on the team’s analysis of data taken by the Gaia and APOGEE instruments...

Scientists working with data from the Sloan Digital Sky Surveys’ Apache Point Observatory Galactic Evolution Experiment (APOGEE) have discovered a “fossil galaxy” hidden in the depths of our own Milky Way. This result, published in Monthly Notices of the Royal Astronomical Society, may shake up our understanding of how the Milky Way grew into the galaxy we see today.

The proposed fossil galaxy may have collided with the Milky Way ten billion years ago, when our galaxy was still in its infancy...

This artist’s impression shows the temperate planet Ross 128 b, with its red dwarf parent star in the background. Credit: courtesy of ESO/M. Kornmesser

Detailed chemical abundances of the Ross 128 help us understand its exoplanet Ross 128 b. Last autumn, the world was excited by the discovery of an exoplanet called Ross 128 b, which is just 11 light years away from Earth. New work from a team led by Diogo Souto of Brazil’s Observatório Nacional and including Carnegie’s Johanna Teske has for the first time determined detailed chemical abundances of the planet’s host star, Ross 128.

Understanding which elements are present in a star in what abundances can help researchers estimate the makeup of the exoplanets that orbit them, which can help predict how similar the planets are to the Earth...

The coloured region is the previously known Galactic disk. The present work has extended its limits much farther away: there is a probability 99.7 percent or 95.4 percent respectively that there are disk stars in the regions outside the dashed/dotted circles. Yellow dot is the position of the Sun. Background Milky Way image from ‘A Roadmap to the Milky Way’. Credit: R. Hurt, SSC-Caltech, NASA/JPL-Caltech

A team of researchers suggests that if we could travel at the speed of light it would take us 200,000 years to cross the disc of our Galaxy. Spiral galaxies such as the Milky Way have discs which are really thin, in which the major fraction of their stars are found. These discs are limited in size, so that beyond certain radius there are very few stars left.

In our Galaxy we were not aware...