How big can stars get?
Hubble Space Telescope high-resolution images of Pismis 24 show two stars orbiting one another. These two are estimated to each be 100 solar masses. In addition, spectroscopic observations with ground-based telescopes further reveal that one of the stars is actually a tight binary that is too compact to be resolved even by Hubble. Image courtesy NASA, ESA, and J. Maíz Apellániz (Instituto de Astrofísica de Andalucía, Spain)
The star cluster Pismis 24 lies 8,000 light-years away in the direction of the constellation Sagittarius. A star in its midst – Pismis 24-1 – was thought to be 200 to 300 times our sun’s mass. In 2007, this object was revealed to be not one but several stars. Now it’s thought stars can’t be more massive than 150 times our sun’s mass.
What was thought to be one of the most massive stars in our Milky Way galaxy turns out to be not just one huge star, but three stars orbiting each other, in a system known as Pismis 24.
Earth & Sky spoke with Jesus Maiz Apellaniz, an astronomer with the Andalucia Institute of Astrophysics in Spain. Maiz Apellaniz said that stars like those in this system are bright, a million times or more brighter than our sun. But this sort of star can be hard to find. They’re short-lived and far away, in this case about 8,000 light-years from Earth.
Jesus Maiz Apellaniz: The birth place for stars are usually clouds that have large amounts of dust, and dust obscures the light from the stars and makes them very hard to detect.
Each of the stars here is still very massive, between 60 and 100 times as massive as our sun. Theories suggest that a star can’t be more massive than 150 solar masses.
With this system now known to be several stars instead of one, the star Eta Carinae remains a good candidate for the title of most massive star known. It’s somewhere around the theoretical mass limit of 150 solar masses.
Our thanks today to Research Corporation, a foundation for the advancement of science.
In your “Shedding Light …” article, you describe Pismis 24 as a double star under the picture, “three” stars orbiting each other in the first paragraph and “four” stars in the last two paragraphs.
So, please shed more light on the CORRECT number of stars in old Pismis 24.
Nelson, thank you! The caption wasn’t complete. I made it more complete. As for the problem between “three” vs. “four” in the script itself … Joel and I mis-spoke. I’ve corrected the error in the transcript, but you can still hear us saying the wrong thing in the audio version (which can’t be corrected at this point).
We apologize.
Our thanks to you for catching this error.
Deborah