Standing almost directly overhead around midnight on July nights is the brilliant bluish-white star, Vega, in the constellation of Lyra, the Harp.

It’s the fifth brightest star in the entire sky and the third brightest visible from mid-northern latitudes, behind Sirius and Arcturus. Also, as seen from mid-northern latitudes such as New York or Madrid, Vega goes below the horizon for only about seven hours a day, meaning that you can see it on any night of the year.

Look directly overhead to find the star Vega in the constellation Lyra. North is at the top of this sky map.
CREDIT: Starry Night Software

This sky map of Vega  shows how the star appears in relation to constellations and other stars.

Astronomers take a fresh look at Vega

Monday, 17 December 2012 by Stuart Gary at ABC

The star Vega is at least two hundred million years older than previously thought, according to a new study.

For thousands of years, scientists have been using Vega as an astronomical yardstick with which to compare other stars and galaxies, as well as develop computer models of stellar life cycles.

vega star

New studies have provided the most accurate estimate yet of the age of Vega, one of the nearest stars to our solar system (Source: NASA/JPL)

But now, new research led by associate professor John Monnier of the University of Michigan, has found Vega is spinning slower than originally estimated, meaning the star is also older.

Reporting in the Astrophysical Journal, Monnier and colleagues determined the star rotates once every 17 hours, rather than once every 12, as previously thought.

By comparison, the Sun’s equator rotates far more slowly, about once every 648 hours or 27 days.

Based on the new analysis of its rotational speed, the researchers determined Vega to be between 700 and 800 million years old, compared to the Sun’s age of 4.567 billion years.

They also found Vega to have about 2.15 times the mass of the Sun.

Using an instrument developed by Monnier called the Michigan Infra-red Combiner, the researchers were able to collect light from six telescopes, increasing the resolution to a hundred times that of the Hubble Space Telescope.

“This allowed us to accurately measure the temperature of Vega, which is seen almost end on from Earth,” says Monnier.

“Because it’s spinning so fast, Vega has an equatorial bulge due to centrifugal force.”

“The greater the bulge, the further away from the star’s centre it’s equator is and that affects its temperature.”

“By measuring the temperature, we could work out how fast Vega is spinning which could then be used to determine its age,” says Monnie

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s