First Author

Vega is the second brightest star in the northern hemisphere and is used by astronomers as a benchmark for assessing the brightness and colour of other stars. But on page 896 of this issue, it is Vega itself that gets assessed, with some surprising results. In the course of testing a new instrument, Deane Peterson at Stony Brook University in New York and his team discovered that Vega rotates rapidly, is slightly tilted on its axis, and is older than was previously thought. Peterson talks to Nature about the effect these results may have.

Why look at Vega?

Vega is the absolute standard: you classify other stars using it. It is also a photometric standard — when you want to measure how much light you're getting from an object you compare its brightness with that of Vega.

But there have been some niggling problems: calibrations for Vega in the visible spectrum that have been extrapolated to the infrared don't quite fit. But these issues have been around for some 30 years and they weren't what motivated our work.

So what did motivate you?

We had used our new interferometer to observe the star Altair, which is not circular in shape. But we also wanted to measure a star that was round, so we looked at Vega. Looking at the data, Vega had the shape we expected. It was only after we wrote our paper on Altair that it occurred to me that we could look at the Vega data in another way. Doing that, we got a signal that wasn't quite symmetrical. Some astronomers had suggested that Vega might be rotating rapidly, and I realized that we had the proof. It turns out we're looking right down the star's axis, which is why we don't see signs of rapid rotation.

As Vega is a benchmark, how will this affect understanding of other stars?

It will ripple through the system. It's like a small tremor; it will be felt everywhere but it won't break anything.

Why is Vega brighter than it should be?

One of the issues was that in general Vega seemed too bright. Normally you would just dismiss it and say it is closer to us than we thought — but we know the distance. In fact, because we are looking at it 4.5° off the poles, it seems a half magnitude brighter.

Your wife is a vet. What, if any, impact does this have on the way you do research?

We don't bring work home together. She's amused when I tell her things she doesn't understand and I'm amused when she tells me things I don't understand. We don't talk shop too much when we get home.