The stellar superhighway in the Milky Way

Mar 21, 2012
Two-armed spiral with a pitch angle of 5.56°, showing the solar orbit (eccentricity 0.159). Orion stream stars are shown at a random position on the inward part of the orbit. Stars in with quality index 1 for stream membership are shown in black, stars with quality indices 2 - 4 are have paler grey for a higher index. Image from MNRAS paper.

Conventional wisdom suggests that, like planets round the Sun, stars follow approximately circular orbits which cross the spiral arms, and that the Sun presently lies in a spur rather than a major spiral arm.

A new study published in (MNRAS) shows that contrary to this belief, nearly half of , including the Sun, have orbits aligned with the Orion arm, one of two major spiral arms.

Of the remainder, one third have orbits aligned with the Centaurus arm, and are currently crossing the Orion arm on their way outwards to rejoining the Centaurus arm later in their orbit. Another third have more eccentric orbits straddling both arms.

According to this research spiral arms are highways for the stars. Stars join the arms in the furthest part of their orbit from the Galactic centre, attracted by the gravity of the arm. They then follow the arm inwards, picking up speed as they go, analogous to marbles in a marble run. Eventually they pick up so much speed that they break free of the gravity of the arm, cross outwards over the other arm and rejoin their original arm to repeat a similar orbit.

The research demonstrates that the Milky Way is a more tightly wound, more extensive, and more regular, two armed spiral than has been thought. The researchers have traced the spiral pattern in the distribution of stars found by the Two Micron All-Sky Survey (2MASS), finding that it extends inwards to about 2.1 kpc from the - the length of the short bar, or "bulge", originally observed by satellite (COBE) in the 1990's. This is about half the length of the so called "long bar", seen now as an artefact due to increased star formation in the near the ends of the short bar.

Explore further: New radio telescope ready to probe

More information: The paper is available at onlinelibrary.wiley.com/doi/10… 012.20693.x/abstract

add to favorites email to friend print save as pdf

Related Stories

New theory of evolution for spiral galaxy arms

Apr 21, 2011

(PhysOrg.com) -- A study of spiral patterns found in galaxies like our Milky Way could overturn the theory of how the spiral arm features form and evolve. The results are being presented by postgraduate student, ...

A new, distant arm of the Milky Way galaxy

Jun 13, 2011

(PhysOrg.com) -- Our Milky Way galaxy, like other spiral galaxies, has a disk with sweeping arms of stars, gas, and dust that curve around the galaxy like the arms of a huge pinwheel.

Astrophysicists map the Milky Way's 4 spiral arms

Jan 05, 2009

Iowa State University's Martin Pohl is part of a research team that has developed the first complete map of the Milky Way galaxy's spiral arms. The map shows the inner part of the Milky Way has two prominent, symmetric spiral ...

Milky Way stars move in mysterious ways

Nov 30, 2010

Rather than moving in circles around the center of the Milky Way, all the stars in our Galaxy are travelling along different paths, moving away from the Galactic center. This has just been evidenced by Arnaud ...

New arm discovered in outer edge of the Milky Way Galaxy

May 23, 2011

(PhysOrg.com) -- In a surprising twist, if you will, Thomas Dame and Patrick Thaddeus, both of the Harvard-Smithsonian Center for Astrophysics, have put forth in a paper to be published in an upcoming issue ...

Spiral arms hint at the presence of planets

Oct 19, 2011

A new image of the disk of gas and dust around a sun-like star has spiral-arm-like structures. These features may provide clues to the presence of embedded but as-yet-unseen planets.

Recommended for you

New radio telescope ready to probe

49 minutes ago

Whirring back and forth on a turning turret, the white, 40-foot dish evokes the aura of movies such as "Golden Eye" or "Contact," but the University of Arizona team of scientists and engineers that commissioned ...

Exomoons Could Be Abundant Sources Of Habitability

23 hours ago

With about 4,000 planet candidates from the Kepler Space Telescope data to analyze so far, astronomers are busy trying to figure out questions about habitability. What size planet could host life? How far ...

Partial solar eclipse over the U.S. on Thursday, Oct. 23

Oct 17, 2014

People in most of the continental United States will be in the shadow of the Moon on Thursday afternoon, Oct. 23, as a partial solar eclipse sweeps across the Earth. For people looking through sun-safe filters, from Los Angeles, ...

A newborn supernova every night

Oct 17, 2014

Thanks to a $9 million grant from the National Science Foundation and matching funds from the Zwicky Transient Facility (ZTF) collaboration, a new camera is being built at Caltech's Palomar Observatory that ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

borc
4.7 / 5 (3) Mar 22, 2012
I would love to see a supercomputer model the movement of the stars. I think it would be beautiful to watch them dance. ;)