Leo's Bright Star Regulus "Flies like Bullet"

[pmbryant]

An interesting study of a bright, famous star (Regulus) is reported here. Unfortunately, the article is poorly written. For instance, I still don't know what is being referred to by the phrase "flies like bullet" in the title.

http://story.news.yahoo.com/news?tmpl=story&cid=96&e=1&u=/space/20050131/sc_space/leosbrightstarregulusflieslikebullet

Leo's Bright Star Regulus Flies like Bullet

Mon Jan 31, 1:18 PM ET
Tariq Malik
Staff Writer
SPACE.com

Shining brightly in the constellation Leo is a fast-spinning star that shoots through the cosmos like an extra-wide bullet, perplexing astronomers as it moves through space in the same direction as its polar axis.

Researchers have long known that Regulus, the brightest star in Leo, spins much faster than the Sun, but new observations with an array of telescopes pinned down the star's odd motion and a host of other characteristics.

"We don't have any idea why it's really doing that," said Georgia State University astronomer Hal McAlister, who led the study of the star at the university's Center for High Angular Resolution (CHARA). "The picture makes me wonder what it would be like to be in a solar system with this type of star."

...

Using the CHARA array of telescopes atop California's Mount Willson, McAlister and his team were able to make the first observations of how Regulus is shaped by its high-speed rotation: 700,000 miles (1.1 million kilometers) an hour spin at its equator.

With such a high rate of rotation -- the Sun, for comparison, has an equatorial spin of about 4,500 miles (7,242 kilometers) an hour -- Regulus bulges out at the center to a diameter about 4.2 times that of Earth's home star. If Regulus spun just 10 percent faster it would rip itself apart, but that's not likely, researchers said.

"There's nothing that we know of that can speed this star up," McAlister told SPACE.com.

...

[sans qualia]

1. I think it means

that Regulus moves like a bullet leaving a rifled barrel ("it moves through space in the same direction as its polar axis").

[pmbryant]

2. You may be right

Though the question then becomes why that rather mundane fact about an otherwise peculiar star would merit placement in the title.

:shrug:

Thanks,
Peter

[htuttle]

3. Uranus flies like a bullet, too

Er, close to that I think. It rotates 'sideways' compared to the Earth, but I'm not sure if it's axes are aligned with it's orbit.

Actually, I just thought it was funny when I thought, 'Uranus flies like a bullet', since I still pronounce 'Uranus' the old school way. :)

[Bill McBlueState]

4. stellar astronomer here

The main finding they're reporting here is that because Regulus spins so quickly, it's distorted well out of the usual spherical shape. Stellar rotation rates play an important role in theories of star and planet formation, so this is of interest to a number of astronomers.

The fact that it's moving through space in the same direction as its rotational axis may also be surprising, but the article doesn't explain this. The headline refers to the star's motion through space, but the subsequent article is really more about the star's rotation.

And then, this sentence doesn't make sense at all: Researchers used measurements of the CHARA array's six telescopes to determine Regulus' temperature, speed spin axis orientation along with a light-combining method called interferometry.

I think they're trying to say, "With a light-combining method called interferometry, researchers used the CHARA array's six telescopes to determine Regulus' temperature, speed, and the orientation of its spin axis."

[pmbryant]

5. Thanks

Thanks for helping to clarify what this is about.

--Peter

[muriel_volestrangler]

6. The star's motion through space relative to what?

the gravitational field of the galaxy? That's all I can think of. Is that really important? Or are they reintroducing an ether?

[Bill McBlueState]

7. relative motion

You're right; a celestial object's motion has to be relative to something. For the young stars I study, we're interested in their motion relative to the gas from which they formed. For a star like Regulus, which I believe is a bit older, the reference frame might be the average of nearby stars.

[Bill McBlueState]

8. the refereed publication

If anyone's interested in the refereed scientific publication, you can find a PDF of it here:

First Results from the CHARA Array. I. An Interferometric and Spectroscopic Study of the Fast Rotator alpha Leonis (Regulus)

It's pretty lengthy, but the introductory and concluding sections might be interesting to non-specialists.

[Ready4Change]

9. Sounds more like flung pizza dough than a bullet.

And that seems like a really odd amount of spin to me. Perhaps its a huge stellar mass being drawn into a black hole? Could that account for the high spin rate and why the spin forces haven't flung the star apart?

[Swede]

10. Stars fly through space,but they also spin,like the earth spins.

This star spins,but it flies through space with one of it's poles facing the direction it is flying.