Randy McDonald (rfmcdpei) wrote,
Randy McDonald

[LINK] Two interesting, and entirely unrelated (I'm sure), news items about our Milky Way Galaxy

We're learning much about our neighbouring worlds and exoplanets, but we're also learning more about our common galactic home the Milky Way Galaxy.

Background time!

As a galaxy, the Milky Way is actually a giant, as its mass is probably between 750 billion and one trillion solar masses, and its diameter is about 100,000 light years. Radio astronomial investigations of the distribution of hydrogen clouds have revealed that the Milky Way is a spiral galaxy of Hubble type Sb or Sc. Therefore, our galaxy has both a pronounced disk component exhibiting a spiral structure, and a prominent nuclear reagion which is part of a notable bulge/halo component. Decade-long observations have brought up more and more evidence that the Milky Way may also have a bar structure (so that it would be type SB), so that it may look like M61 or M83, and is perhaps best classified as SABbc. Recent investigations have brought up support for the assumption that the Milky Way may even have a pronounced central bar like barred spiral galaxies M58, M91, M95, or M109, and thus be of Hubble type SBb or SBc.

First comes the New York Times article by Dennis Overbye, "Bubbles of Energy Are Found in Galaxy".

Something big is going on at the center of the galaxy, and astronomers are happy to say they don’t know what it is.

A group of scientists working with data from NASA’s Fermi Gamma-Ray Space Telescope said Tuesday that they had discovered two bubbles of energy erupting from the center of the Milky Way galaxy. The bubbles, they said at a news conference and in a paper to be published Wednesday in The Astrophysical Journal, extend 25,000 light years up and down from each side of the galaxy and contain the energy equivalent to 100,000 supernova explosions.

“They’re big,” said Doug Finkbeiner of the Harvard-Smithsonian Center for Astrophysics, leader of the team that discovered them.

The source of the bubbles is a mystery. One possibility is that they are fueled by a wave of star births and deaths at the center of the galaxy. Another option is a gigantic belch from the black hole known to reside, like Jabba the Hutt, at the center of the Milky Way. What it is apparently not is dark matter, the mysterious something that astronomers say makes up a quarter of the universe and holds galaxies together.

“Wow,” said David Spergel, an astrophysicist at Princeton who was not involved in the work.

“And we think we know a lot about our own galaxy,” Dr. Spergel added, noting that the bubbles were almost as big as the galaxy and yet unsuspected until now.

Next comes Wired Science's Dave Mosher, with the news that the "Milky Way May Fizzle Out Sooner Than Expected".

A thick bar of stars, gas and dust spanning across the Milky Way’s center could be speeding star formation and, as supplies run out, our host galaxy’s eventual death.

A new study, the first to trickle out of Galaxy Zoo’s second crowd-sourced scientific effort, buoys the idea that bars somehow encourage galaxies to form big, blue and short-lived stars, as well as funnel gas and dust to supermassive black holes lurking at their cores. In the process, bars may quickly consume star-making materials to leave behind only a “dead” galaxy of red and fading stars.

“Basically, as you go from the really youthful galaxies to the dead ones, more and more frequently we see bars in them,” said Kevin Schawinski, an astronomer at Yale University and co-author of the study, set to appear in an upcoming edition of the Monthly Notices of the Royal Astronomical Society. “Our immediate suspicion is that bars are involved in speeding galaxy evolution.”

Schawinski said the work isn’t proof that bars shorten galaxies’ star-forming lifespans — it could be the other way around, with bars being a product of dying galaxies. But he said the data backs the first idea, which is shared among many astronomers.

“Bars seem to help exhaust supplies of gas, pushing galaxies to a passive state and no longer forming any stars. This is inline with our results and what others are saying,” Schawinski said. “The Milky Way, which is more or less agreed to be a barred spiral, may be an example of a galaxy in transition from an active state to something anemic and passive.”

Galactic bars and energy bubbles are unconnected, right? The very idea of astroengineering being feasible is ridiculous, regardless.

Anyway, as Mosher notes, catastrophe may save our galaxy regardless!

When the Milky Way does run out of available stellar fuel and succumbs to its reddish death, which is extremely difficult to precisely predict, all may not be lost. The nearby Andromeda galaxy is expected to collide with our galaxy in about 4.5 billion years.

“When the Andromeda galaxy collides and merges with the Milky Way, it’s going to be spectacular fireworks of star formation,” Schawinski said, noting how gravity-induced chaos should stir up diffuse gas and dust. “Maybe even the galaxies’ black holes will start feeding again, too.”
Tags: links, space science
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