Largest Yellow Star Ever Seen Revealed in New Light

7

A powerful telescope in Chile has imaged the largest yellow star ever discovered.

The star, called HR 5171 A, shines 12,000 light-years from Earth in the center of a new image released today (March 12). Known as a "yellow hypergiant," The star is more than 1,300 times the diameter of the sun, much larger than scientists expected after earlier observations, European Southern Observatory officials said in a statement. You can see the yellow hypergiant in a new video from ESO as well.

The new measurements place the star as one of the top 10 largest stars ever discovered. Scientists using ESO's Very Large Telescope Interferometer to observe the star got another surprise as well. HR 5171 A is actually part of a double star system, with its companion orbiting extremely close to the hypergiant.

HR 5171 A is 50 percent larger than the red supergiant Betelgeuse, the star that makes up one of the constellation Orion's shoulders. Only 12 yellow hypergiants have been found in the Milky Way, and they are in an unstable stage of life, according to ESO. Yellow hypergiants are rapidly changing, and shoot out material that forms a large atmosphere around the star.

"The new observations also showed that this star has a very close binary partner, which was a real surprise," Olivier Chesneau, a scientist of the Observatoire de la Côte d’Azur in France working with the VLT said in a statement. "The two stars are so close that they touch and the whole system resembles a gigantic peanut … The companion we have found is very significant as it can have an influence on the fate of HR 5171 A, for example, stripping off its outer layers and modifying its evolution."

Written By: Miriam Kramer
continue to source article at livescience.com

7 COMMENTS

  1. Was it Lawrence Kraus who said something like :**The universe is both very big and very old, and strange things are happening all the time. ** ?

    Why am I not surprised by this magnificent discovery ? For the reasons cited above !

    • In reply to #1 by Mr DArcy:

      Was it Lawrence Kraus who said something like :The universe is both very big and very old, and strange things are happening all the time. ?

      Why am I not surprised by this magnificent discovery ? For the reasons cited above !

      Not sure if I would call it strange. Our sample size is way too small and will most likely never be adequate enough to even begin to understand what would be classified as strange. Am I being a dick for saying that?

      • In reply to #2 by aquilacane:

        In reply to #1 by Mr DArcy:

        Was it Lawrence Kraus who said something like :The universe is both very big and very old, and strange things are happening all the time. ?

        Why am I not surprised by this magnificent discovery ? For the reasons cited above !

        Not sure if I would call it strange. Our s…

        I would think it’s an Einstein thing, strange is relative to what we’re stuck with, after that, it’s even stranger.

  2. Need help here please. Why doesn’t gravity cause these two stars to rapidly merge into one? Is it because of the distance between their cores rather than their surfaces? Also, why aren’t they orbiting each other at a great velocity? Apologies for the pedantry…

    • In reply to #5 by BroughtyBoy:

      Need help here please. Why doesn’t gravity cause these two stars to rapidly merge into one? Is it because of the distance between their cores rather than their surfaces? Also, why aren’t they orbiting each other at a great velocity? Apologies for the pedantry…

      For the same reasons that gravity does not cause the Earth and the Moon to rapidly merge into one. Orbiting bodies have both kinetic energy of rotation and angular momentum. Both of these must dissipate and be eliminated for gravity to be able to pull the orbiting bodies together. When such dissipating effects exist, the orbiting bodies will approach and eventually merge.

      Oddly enough, the rotation of Earth provides kinetic energy and angular momentum to our Moon. The ocean tides are involved in this process. The result is that the Moon is continually boosted into a higher orbit at about 1.48 inches each year. As the Earth provides this energy boost the Moon, the rotation of the Earth is decreased. Our days and nights are getting longer.

      The fact that the binary star system is made of gas does not matter. Energy and momentum still need to be dissipated in order for the stars to approach each other and merge.

  3. In reply to #5 by BroughtyBoy:

    Need help here please. Why doesn’t gravity cause these two stars to rapidly merge into one? Is it because of the distance between their cores rather than their surfaces? Also, why aren’t they orbiting each other at a great velocity? Apologies for the pedantry…

    Some information on this hypergiant star is given here, where the final sentence is:

    “The astronomers concluded that the star is in a binary system by studying the data contributed by several observatories and determined the system as an eclipsing binary star system with the smaller companion star orbiting the larger HR 5171A once every 1300 days.”

    If the days mentioned here are Earth days, then that is a pretty rapid orbit around a star that has a diameter 1300 times greater than that of our own placid little sun. But I too would be interested to hear from the more astronomically knowledgeable about this.

Leave a Reply