Astronomy Picture of the Day 12-29-02

NASA ^ | 12-29-02 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 December 29

NGC 1818: A Young Globular Cluster
Credit: Diedre Hunter (Lowell Obs.) et al., HST, NASA

Explanation: Globular clusters once ruled the Milky Way. Back in the old days, back when our Galaxy first formed, perhaps thousands of globular clusters roamed our Galaxy. Today, there are perhaps 200 left. Many globular clusters were destroyed over the eons by repeated fateful encounters with each other or the Galactic center. Surviving relics are older than any Earth fossil, older than any other structures in our Galaxy, and limit the universe itself in raw age. There are few, if any, young globular clusters in our Milky Way Galaxy because conditions are not ripe for more to form. Things are different next door, however, in the neighboring LMC galaxy. Pictured above is a "young" globular cluster residing there: NGC 1818. Observations show it formed only about 40 million years ago - just yesterday compared to the 12 billion year ages of globular clusters in our own Milky Way

[petuniasevan]

Why are there "young" globulars found in the Large Magellanic Cloud? Could it have something to do with that galaxy's interactions with our own Milky Way? If so, why doesn't the Milky Way show some similar star clusters?

A Harvard study lends credence to the theory that the young globular clusters formed from spherical dust-and-gas clouds (like giant molecular clouds), according to computer models. Still, that's only half of an answer. What causes the conditions necessary for recent globular cluster formation in the first place? Why have those conditions been met in the LMC but not our own galaxy?

[petuniasevan]

[Jemian]

Thank you.

BTTT

[GodBlessRonaldReagan]

Great pic - thanks for the ping!

[lonestar]

Thanks again for your efforts. I so enjoy these pics.

[Soaring Feather]

Thank you for these wonderful pitcures.

[SuziQ]

I had never seen any globular clusters before until our trip to AZ a couple of years ago. We went to the Lowell Observatory and attended a short talk about them, then looked at them through the huge brass telescope they have there. Of course we couldn't seen them as well as this picture shows, but we could see the brightest stars in them.