Vega, the Star at the Center of Everything

Vega, the fifth-brightest nighttime star, beams almost straight overhead early this month and may be the most important luminary in the sky after the Sun. But how exactly do you say its name? Is it VEE-guh or VAY-guh?

In July 2006, Sky & Telescope's Tony Flanders addressed the question:

"In 1941 the American Astronomical Society (AAS) formed a committee of Samuel G. Barton, George A. Davis, Jr., and Daniel J. McHugh to consult with astronomers, educators, Arabic scholars, and planetarium lecturers and come up with a list of preferred pronunciations for common star names and constellations. Their final report, adopted by the AAS, appeared in Sky & Telescope for June 1943, page 12."

They decided that Vega should be pronounced VEE-guh. This made sense because for centuries it had been known as Wega and spoken as WE-guh, which means descending eagle in Arabic. Later, the W evolved into a V, but the pronunciation remained the same: VEE-guh. As a budding amateur astronomer in 1966, I owned an Edmund planisphere that included an instruction manual with a pronunciation guide in line with AAS standards.

Say what?

Yet somewhere along the way Vega became (mostly) VAY-guh, leaving me and my ilk in the minority. Nowadays, the online Merriam-Webster dictionary gives both pronunciations, while the American Heritage Dictionary lists VEE-guh. Recognizing that language evolves, I tell newcomers to the hobby that either is correct.

I have a hunch that the shift to VAY-guh, at least in the U.S., occurred for several reasons. First, the country has a sizable Spanish-speaking population. In Spanish the "e" sound is pronounced "ay" not "ee." Think Las Vegas. In fact, Vega is a common Spanish surname and means "meadow" or "fertile plain." But I also suspect the Chevrolet Vega had something to do with the whole business.

Named for the star and pronounced VAY-guh, the car was a big hit in the early 1970s until owners discovered it was prone to gas tank fires, rapid rusting, and melting engine parts. The rise and fall of the Vega from happy TV commercials to infamy seared its name (and pronunciation) in the public memory. While we're on the topic, in the 1997 movie Contact, Jodie Foster, as Dr. Ellie Arroway, receives a message from sentient beings on a planet around Vega, pronounced VAY-guh (ugh!) throughout the film. To brush up on star names, consult this star and constellation pronunciation guide or listen to this audio version.

However your say it, Vega is a white, brilliant, and radiant star. With a declination of nearly +39°, it shines directly overhead for anyone living at latitude 39° north. A quick look reveals several large cities share this good fortune: Topeka, Kansas; Dover, Delaware; Baltimore, Maryland; Cincinnati, Ohio; and Kansas City, Missouri. From my site at 47° north, it passes south of the zenith but close enough to require some serious neck-twisting at culmination.

For many, Vega is a harbinger of summer in the dead cold of winter, glittering between bare branches in the northeastern sky around 1 a.m. local time in late February. I love seeing it rise during my late-night walks. As a child, I watched it climb over the neighbor's snowy backyard from my bedroom window when I was supposed to be asleep.

Vegan promise

Living in Duluth, Minnesota, where winters can be tenacious, Vega brings hope. It's also inextricably tied to the summer as the brightest star in the expansive Summer Triangle asterism. From my latitude, Vega rises first, followed by Deneb and Altair in that order. The trio frames one of the brightest, thickest segments of the Milky Way. From light-polluted, mid-latitude skies, it may be the only section of Milky Way most people ever get to see.

Come fall, Vega is the first of the trio to tilt to the west. Although its northerly declination keeps the star in view for many months, I hate to see it go. If you live north of latitude 51° Vega never leaves your sight because it's circumpolar and never sets. I wonder if anyone has ever seen Vega at its nadir from London, England, when the star hovers only ½° above due north.

On the night of July 16–17, 1850, Vega became the first star after the Sun to have its picture taken. James Adams Whipple and William Bond used the 15-inch refractor at Harvard College Observatory to focus Vega's light onto a sheet of silver-plated copped sensitized with iodine vapors, exposing for about 20 minutes. The anticipation they must have felt watching the image develop over hot mercury fumes must have been just as intense as our wait for the first photos to download from the James Webb Space Telescope.

First again!

In August 1872, amateur astronomer Henry Draper selected Vega as the first nighttime star to have its spectrum photographed. Draper's image revealed the classic absorption lines of hydrogen known as the Balmer series. This step-like sequence of lines results when electrons in a hydrogen atom located at higher energy levels drop down to level 2, the second closest to the nucleus. Each downward drop releases a photon of energy. An electron diving from level 3 to 2 spits out a photon of deep-red light — the familiar H-alpha line. A tumble from 4 to 2 yields H-beta; 5 to 2, H-gamma; and so on.

Amateur spectroscopists routinely record the Balmer series in Vega and other stars of its spectroscopic class. With a visual instrument, such as the Rainbow Optics Star Spectroscope, the spectral lines are very distinct at the eyepiece. Although that model is no longer available, used spectroscopes show up from time to time on Cloudy Nights. For a modest sum you can also photograph star spectra with your DSLR or mirrorless camera. It's one thing to look at a star and know it's made of hot plasma, but quite another to see hydrogen's "bar code" directly with your own eyes. Vega's prominent lines make it a great place to start.

On the basis of its hydrogen lines, Vega was used to identify and classify similar stars of its type including Sirius, Altair, and Fomalhaut. Based on its "plain vanilla" spectrum and steady light, it's served duty since 1943 as one of the stable standard stars by which others are classified. Vega is a bluish-white, class A0 main sequence star that's 2.1 times as massive as the Sun and about 2.5 times as big located 25 light-years away.

Both its proximity and luminosity (40 times greater than the Sun) make it one of the brightest stars in the sky. It shines at magnitude +0.03 and for years was the standard reference for the magnitude-zero point used to calibrate the magnitude scale on photoelectric devices.

Ring 2.0

Like the Sun, Vega burns hydrogen in its core, but because it's hotter and more massive, it will exhaust its energy reserves sooner. At present, the star is about 455 million years old. Vega will leave the main sequence in about 500 million years and bloat into a red giant before expelling its atmosphere and evolving into a white dwarf encircled by a planetary nebula. The next time you observe the Ring Nebula (M57), imagine Vega as its replacement long after the current Ring has expanded and faded beyond recognition.

Young stars often rotate rapidly, and Vega is no exception, spinning once on its axis every 12.5 hours. Compare that to our sluggard Sun, which takes an average of 27 days. Gaseous objects like stars flex as they spin, so Vega's speedy rotation has stretched it into an egg-like shape called an oblate spheroid. Its equator diameter is 2.82 times that of the Sun, with a polar diameter of 2.36 solar, a difference of 19 percent. From our earthly vantage point we look almost straight down one of its poles.

Vega's shape combined with its rapid spin heats up the polar regions and chills the equatorial zone, making the pole brighter than the equator, a phenomenon known as gravity darkening. The temperature difference is significant: 9,700°C (17,500°F) in the polar regions versus 7,900°C (14,200°F) at the equator.

Planet or catastrophe?

While Vega may host an as-yet-unconfirmed Neptune-size planet, we have definitive proof of a dusty debris disk surrounding the star that's likely composed of an amalgam of silicate and carbonaceous grains. The rubbly ring may be home to protoplanets in the rough-and-tumble process of becoming full-fledged planets or the dusty aftermath of a large and recent collision. The Infrared Astronomical Satellite (IRAS) detected an excess of warm, infrared emission around the star in 1983, later photographed by NASA's Spitzer Space Telescope. I should note that the discovery was another feather in Vega's cap — the first star discovered surrounded by a disk of warm dust.

Back in 12,000 BC, Vega was the Pole Star and will be again around AD 13,700. Gravitational forces exerted by the Sun and Moon on Earth's equatorial bulge causes the axis to slowly gyrate with a period of around 26,000 years. Right now, the north polar axis points at Polaris in the Little Dipper, our current North Star. But 12,000 years hence it will aim toward Vega, ensuring that the star's notoriety will persist for millennia. There's more. Ten precession cycles from now it will pass nearest Earth and shine brighter than ever at magnitude –1.4!