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

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).

THE HITCHCHIKER'S GUIDE TO THE LOCAL SUPERCLUSTER

Image: Virgo Supercluster. Credit: Andrew Z. Colvin The Virgo Supercluster is a region with a diameter of 33 megaparsecs (~1000 times larger the Milky Way's diameter) containing at least 100 galaxy groups and clusters.

Hubble Spots Expanding Light Echo around Supernova

Light Echo around SN 2014J in M82 . Credits NASA , ESA , and Y. Yang (Texas A&M University and Weizmann Institute of Science, Israel). Acknowledgment: M. Mountain (AURA) and The Hubble Heritage Team ( STScI /AURA) Light from a supernova explosion in the nearby starburst galaxy M82 is reverberating off a huge dust cloud in interstellar space. The supernova, called SN 2014J, occurred at the upper right of M82, and is marked by an “X.” The supernova was discovered on Jan. 21, 2014. The inset images at top reveal an expanding shell of light from the stellar explosion sweeping through interstellar space, called a “light echo.” The images were taken 10 months to nearly two years after the violent event (Nov. 6, 2014 to Oct. 12, 2016). The light is bouncing off a giant dust cloud that extends 300 to 1,600 light-years from the supernova and is being reflected toward Earth. SN 2014J is classified as a Type Ia supernova and is the closest such blast in at least four ...

SpaceTime

Search This Blog