The Red Hypergiant VY CMa Is Bigger Than Betelguese and Belching Out Vast Clouds of Dust

SyFy.com ^

[BenLurkin]

[I]n this case we're talking about the star VY Canis Majoris (or VY CMa for short). This ridiculously bloated red hypergiant is about 4,000 light years away in the constellation of Canis Major... VY CMa is an immense star, well over 2 billion kilometers wide.

Observations of the star show that it is blasting out way too much infrared light for a star of its kind, which is a telltale sign that it's surrounded by dust. This is usually microscopic grains of rocky (silicate-laden) or carbonaceous (sooty) material around the star (so we call it circumstellar, which is just a cool word). It's warmed by the starlight and so it glows in the infrared, causing the observed excess.

Extremely high-resolution observations of VY CMa show this dust, and they also show it's pretty complex. There are knots, clumps, arcs, and diffuse clouds around the star. New observations using Hubble, though, allowed astronomers to measure the speed at which all this dust is moving — much of it was ejected at tens of thousands of kilometers per hour.

The beauty of this is that they then measured the distance from the star to these various clumps and used that in conjunction with the velocity to trace the clumps backwards in time, to see when they got ejected. What they found is interesting indeed… the ages of the various clumps and other features indicate they were blown off the star around 70, 120, 200, and 250 years ago.

Looking at historical observations of the star, these periods coincide with times of great brightness variability in the star, dimming and brightening by a large factor.

[Deaf Smith]

If the clumps and dust were blown off 70-250 years ago and the star is 4000 light years away, how are we able to observe and calculate this event?

The event should still be 3750-3930 years away from observation.

[SaveFerris]

“Belching out vast clouds of dust”

Hey, I think I dated her once...

[ThunderSleeps]

You and me both! ;-) Seriously though, as the other poster pointed out, the writing is sloppy.

[PTBAA]

Would Monsieur Giant care for a wafer-thin mint?

[Ozark Tom]

Is the rotation axis pointing this direction?

[Conan the Librarian]

And why Betelgeuse? There are quite a number of stars out there that are bigger.

[outofsalt]

"it is blasting out way too much infrared light for a star of its kind, which is a telltale sign that it's surrounded by dust."

Allergies are kicking up with Spring almost here.

[BitWielder1]

Because astronomers time events when we see them (or would have seen them) from Earth.
We don't always know exactly how far away they are but we do know when the light reaches us.

[Tallguy]

Carburetor is set a little bit ‘rich’. Better lean it out.

[Sirius Lee]

Pics, or it didn't happen four thousand years ago.

[Paul R.]

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