Hubble & Gaia Accurately Weigh the Milky Way

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Hubble & Gaia Accurately Weigh the Milky Way

Post by bystander » Thu Mar 07, 2019 6:02 pm

Hubble & Gaia Accurately Weigh the Milky Way
ESA Hubble Science Release | 2019 Mar 07
Click to play embedded YouTube video.
Globular Clusters Surrounding the Milky Way (Artist’s Impression)
Credit: ESA/Hubble, NASA, L. Calçada, M. Kormesser

In a striking example of multi-mission astronomy, measurements from the NASA/ESA Hubble Space Telescope and the ESA Gaia mission have been combined to improve the estimate of the mass of our home galaxy the Milky Way: 1.5 trillion solar masses.

The mass of the Milky Way is one of the most fundamental measurements astronomers can make about our galactic home. However, despite decades of intense effort, even the best available estimates of the Milky Way’s mass disagree wildly. Now, by combining new data from the European Space Agency (ESA) Gaia mission with observations made with the NASA/ESA Hubble Space Telescope, astronomers have found that the Milky Way weighs in at about 1.5 trillion solar masses within a radius of 129 000 light-years from the galactic centre.

Previous estimates of the mass of the Milky Way ranged from 500 billion to 3 trillion times the mass of the Sun. This huge uncertainty arose primarily from the different methods used for measuring the distribution of dark matter — which makes up about 90% of the mass of the galaxy. ...

What Does the Milky Way Weigh? Hubble and Gaia Investigate
NASA | GSFC | STScI | HubbleSite | 2019 Mar 07

Evidence for an Intermediate-Mass Milky Way from Gaia DR2 Halo Globular Cluster Motions ~ Laura L. Watkins et al
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Re: Hubble & Gaia Accurately Weigh the Milky Way

Post by neufer » Thu Mar 07, 2019 11:04 pm

  • Ergo: at almost 5 times the distance that the Sun is from the Galactic Center
    the "almost constant" orbital velocity has only dropped by about one sixth
    (; hence, taking 6 times as long to orbit the galaxy than the Sun). wrote:
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Re: Hubble & Gaia Accurately Weigh the Milky Way

Post by Ann » Fri Mar 08, 2019 4:54 am

So fascinating!

Colliding galaxies NGC 5426 and NGC 5427.
Adam Block/Mount Lemmon SkyCenter/University of Arizona
What does this say about the mass of the Milky Way compared with the mass of Andromeda?

Perhaps the collision between the Milky Way and Andromeda will be like the interaction (and upcoming collision and merger) between NGC 5426 and NGC 5427?
Anne's Astronomy wrote:

Arp 271 is a pair of interacting spiral galaxies: NGC 5426 (the more oblique galaxy at left) and NGC 5427 (the nearly face-on spiral galaxy at right). Together they are about 130,000 light-years across and located some 90 million light-years away towards the constellation of Virgo.

The galaxies are in the throes of a slow but disturbing interaction, that began likely a several million years ago. These twin galaxies — which have similar sizes, masses, structures, and shapes with expansive arms and a compact core – appear undisturbed. But the mutual pull of gravity has already begun to alter and distort their visible features.
So are the Milky Way and Andromeda also similar in mass and size, if not in structure and shape?

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