Upper Limit on the Milky Way Mass

This image from the Hubble Space Telescope shows the small galaxy called the Sagittarius dwarf irregular galaxy, or "SagDIG" for short. SagDIG is relatively nearby, and Hubble's sharp vision is able to reveal many thousands of individual stars within the galaxy. Credit: NASA, ESA, and The Hubble Heritage Team STScI/AURA

As one of the most massive Milky Way satellites, the Sagittarius dwarf galaxy has played an important role in shaping the Galactic disk and stellar halo morphologies. The disruption of Sagittarius over several close-in passages has populated the halo of our Galaxy with large-scale tidal streams and offers a unique diagnostic tool for measuring its gravitational potential.

In a recent paper (Dierickx, Loeb 2017) the authors test different progenitor mass models for the Milky Way and Sagittarius by modeling the full infall of the satellite. They constrain the mass of the Galaxy based on the observed orbital parameters and multiple tidal streams of Sagittarius.

This artist's concept depicts the most up-to-date information about the shape of our own Milky Way galaxy. Credits: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

Their semi-analytic modeling of the orbital dynamics agrees with full N-body simulations, and favors low values for the Milky Way mass, ≤ 10¹²M_Sun.

Marion I. P. Dierickx, Abraham Loeb - Upper Limit on the Milky Way Mass from the Orbit of the Sagittarius Dwarf Satellite - (arXiv)

Comments

ABOUT THE FORMATION OF THE COLD CLASSICAL KUIPER BELT

Image: The Kuiper Belt. Credit: NASA . The Kuiper belt is a circumstellar disc in the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt (the circumstellar disc located roughly between the orbits of the planets Mars and Jupiter), but it is far larger-20 times as wide and 20 to 200 times as massive.

ORIGIN OF RADIO EMISSION IN RADIO-QUIET QUASARS

Image Credit: NASA/Goddard Space Flight Center Radio emission of radio-quiet quasars may be due to stars formation in the quasar host galaxy, to a jet launched by the supermassive black hole, or to relativistic particles accelerated in a wide-angle radiatively-driven outflow.

VISTA Gazes Into Carina Nebula In Infrared

This spectacular image of the Carina nebula reveals the dynamic cloud of interstellar matter and thinly spread gas and dust as never before. Credit: ESO/J. Emerson/M. Irwin/J. Lewis About 7500 light-years away, in the constellation of Carina , lies a nebula within which stars form and perish side-by-side. Shaped by these dramatic events, the Carina Nebula is a dynamic, evolving cloud of thinly sprea d interstellar gas and dust. Spanning over 300 light-years, the Carina Nebula is one of the Milky Way's largest star-forming regions and is easily visible to the unaided eye under dark skies. Unfortunately for those of us living in the north, it lies 60 degrees below the celestial equator, so is visible only from the Southern Hemisphere. The massive stars in the interior of this cosmic bubble emit intense radiation that causes the surrounding gas to glow. By contrast, other regions of the nebula contain dark pillars of dust cloak...

SpaceTime

Search This Blog