On the occasion of the 31st anniversary of the Hubble Space Telescope, astronauts pointed it in the direction of a giant star that is “on the brink of destruction.”
The gigantic star, called AG Carinae, featured in this latest image, is tugging between gravity and radiation to avoid self-destruction.
It is surrounded by an expanding shell of gas and dust, also called a nebula, formed by the giant star’s powerful winds.
This nebula around the star is about five light years wide – about the same distance between the sun and our nearest star, Alpha Centauri.
Hubble, a joint project of NASA and European Space Agency (ESA), launched for low Earth orbit in 1990 and has taken a ‘birthday photo’ of a distant object every year.
The giant star, called AG Carinae, featured in this latest image, is tugging between gravity and radiation to avoid self-destruction
AG CARINAE: A LUMINOUS BLUE VARIABLE STAR
AG Carinae is a luminous blue variable star located about 19,570 light-years away.
It is one of the brightest stars in the Milky Way, about a million times brighter than our own sun.
It is surrounded by a nebula of ejected gas and dust that spreads about five light years from the star.
- Zodiac sign: Carina
- Mass: 55 times the mass of the sun
- Radius: 50-500 times the radius of the sun
- Temperature: 8,000 to 26,000 Kelvin
It is in transition between a blue supergiant and a Wolf-Rayet star.
Wolf-Rayet stars are among the hottest types of stars, reaching up to 210,000 K in intense winds.
The huge structure around AG Carinae was created from one or more gigantic eruptions several thousand years ago.
The outer layers of the star were blown into space, the ejected material about 10 times the mass of our sun.
These eruptions are typical of the life of a rare star race called a Luminous Blue Variable (LBV), a brief unstable phase in the short life of an ultra-bright, glamorous star that lives quickly and dies young.
These stars are among the heaviest and brightest stars known and only live a few million years – compared to the 10 billion year lifespan of our own star.
AG Carinae is a few million years old and is located 20,000 light years away in our Milky Way Galaxy and will live up to six million years.
LBVs have dual personalities, appear to spend years in semi-bliss, then erupt into a tantalizing burst as their brightness increases.
The star is believed to be about 70 times more massive than the sun and up to a million times brighter than our own star.
Large eruptions like the one that produced the nebula seen in the new Hubble image occur a few times during an LBV’s life and are thrown off when there is a risk of self-destruction.
Due to their massive shapes and super-high temperatures, luminous blue variable stars such as AG Carinae are in a constant battle to maintain stability.
It’s an arm wrestling match between radiation pressure from inside the star pushing out and gravity pushing in. This competition results in the star expanding and contracting.
The outward pressure occasionally wins the battle, and the star expands to such an immense size that it blows off its outer layers, like an erupting volcano.
But this eruption only takes place when the star is about to disintegrate. After the star ejects the material, it contracts to its normal size, settles down and becomes stable again.
LBV stars are rare, with fewer than 50 known galaxies in our local group of neighboring galaxies.
These stars spend tens of thousands of years in this phase, the blink of an eye in cosmic time. Some are expected to end their lives with gigantic supernova explosions, enriching the universe with the heavier elements beyond iron.
Shown here is the region of the sky around the star AG Carinae, which is positioned in the center of the image
LUMINOUS BLUE VARIABLE STARS
A luminous blue variable (LBV) star shows unpredictable and sometimes dramatic variations in brightness.
They are a form of massive evolved star, also known as S Doradus variables.
LBVs are huge unstable supergiants and hypergiants with periodic eruptions and large eruptions.
During a normal eruption, the star’s temperature drops by about 30%.
They can reach a maximum brightness one million times that of the sun, with dimensions up to 100 times the mass of the sun.
Like many other LBVs, AG Carinae remains unstable. It has experienced lesser eruptions that were not as powerful as the one that created the current nebula.
Although AG Carinae is now semi-quiet, its scorching radiation and powerful stellar wind have shaped the old nebula, forming intricate structures as outflowing gas slams into the slower-moving outer nebula.
The wind travels at a speed of 1 million kilometers per hour, about 10 times faster than the expanding nebula. Over time, the hot wind catches up with the cooler expelled material, plows in, and pushes it further away from the star.
The red material seen in the image, at the outer edge of the nebula, is glowing hydrogen gas laced with nitrogen gas.
The most prominent features, highlighted in blue, are thread-like structures in the shape of tadpoles and crooked bells.
These structures are clumps of dust that are illuminated by the light from the star. The tadpole-shaped features most noticeable on the left and bottom are denser clumps of dust formed by the stellar wind.
Hubble’s sharp view reveals these delicate-looking structures in great detail.
For its 30th anniversary, Hubble captured an image called the ‘cosmic reef’ because of its resemblance to an underwater world.
It showed the giant red nebula NGC 2014 and its smaller blue neighbor NGC 2020 belonging to the Large Magellanic Cloud, a satellite galaxy of the Milky Way.
NASA’s Hubble Space Telescope is still operational and has made more than 1.3 million observations since the mission’s inception in 1990
The Hubble telescope was launched on April 24, 1990 via the space shuttle Discovery from Kennedy Space Center in Florida.
It is named after the famous astronomer Edwin Hubble who was born in Missouri in 1889.
He is perhaps best known for discovering that the universe is expanding and the rate at which that is happening – now that invented the Hubble constant.
The Hubble telescope is named after the famous astronomer Edwin Hubble who was born in Missouri in 1889 (photo)
Hubble has made more than 1.3 million observations since its mission began in 1990 and helped publish more than 15,000 scientific papers.
It orbits the Earth at about 17,000 mph (27,300 km / h) in low Earth orbit at about 540 miles elevation.
Hubble has a pointing accuracy of .007 arc seconds, which is the same as being able to shine a laser beam aimed at Franklin D. Roosevelt’s head on a dime approximately 200 miles away.
The Hubble telescope is named after Edwin Hubble who was responsible for inventing the Hubble constant and is one of the greatest astronomers of all time
Hubble’s main mirror is 2.4 meters wide and 13.3 meters long in total – the length of a large school bus.
The launch and deployment of Hubble in April 1990 marked the most significant advance in astronomy since the Galileo telescope.
Thanks to five service missions and more than 25 years of operation, our view of the universe and our place in it has never been the same.