A Lonely, Wandering Hermit of a Galaxy

Tells astronomers a thing or two about star birth throughout the cosmos 

A mysterious hermit

Space news (astrophysics: irregular dwarf galaxies; the formation of new stars) – a lonely, undefined looking galaxy an estimated 4.2 million light-years from Earth, approximately 2.3 million light-years from Leo A –  

The Sagittarius Dwarf Irregular Galaxy (SagDIG) is a metal-poor galaxy from the dawn of the cosmos. Almost as old as the universe, SagDIG is showing us things about the evolution of everything we see during our journey to the beginning of space and time. Spanning about 1,500 light-years, this ancient star wanderer is about 3.5 million light-years distant toward the constellation Sagittarius.

Astronomers think the chaotic, unusual looking smaller island universe seen in the Hubble Space Telescope image here hasn’t merged with any other galaxies lately. Classified as an irregular dwarf galaxy, UGC 4879 has no obvious form and lacks the magnificent whirl of a spiral galaxy or the coherence of an elliptical. Approximately 1.36 million parsecs from Earth this lonely, wandering hermit of a galaxy is showing astronomers new, interesting things about star birth in the universe

Irregular dwarf galaxy Leo A seen here has a much more complicated formation history than astronomers first thought. The simple structure astrophysicists were expecting isn’t what we see here. Instead, Leo A shows hints of an evolution just as chaotic and unpredictable as larger island universes. 

Spectral data of UGC 4879 indicates radial velocities for different sections of the galaxy, which could indicate the presence of a stellar disk. This lonely, isolated wanderer is studied closely and intensely by astronomers because of its history of few interactions with other galaxies. This isolation makes it less complicated to piece together its history of star birth and an ideal laboratory for study. 

Dwarf irregular galaxy NGC 1569 seen here underwent a brief starburst period about 25 million years ago. Hidden within the chaos are monstrous, gigantic supermassive stars and envelopes of gas expelled by huge stars that recently went supernova. Only 11 million light-years away in the long-necked constellation Camelopardalis and spanning 8,000 light-years, the blue, white hot young stars within are perfect for study. Credit: NASA/ESA/STScI/Hubble Heritage

Study of UGC 4879 indicates during the first 4 billion years after the beginning of the universe new stars were being born at a pretty fast rate. The next nine billion years of relative inactivity followed by a recent starburst about 1 billion years ago is a puzzle for astronomers. They continue to study this hermit of a galaxy hoping to find out more about both its history and the complex riddles of sun birth across the cosmos.  

Irregular dwarf galaxy NGC 4449 seen here is undergoing an intense period of starburst, with young, blue-white stars being created at an amazing rate and pinkish star forming regions in this deep colour image. Only 12.5 million light-years away in Canes Venatici, the constellation of the Hunting Dogs, NGC 4449’s the first such galaxy to have an identified star stream in the lower right composed mainly of supermassive red giant stars. These types of galaxies are thought to have a significant dark matter halo, which is a chance for astronomers to study the dark side’s role in the evolution and formation of galaxies. Credit: NASA/ESA/STScI 

Read about one of the most massive black holes ever discovered residing in a backwater part of the cosmos.

For the first time in space history the first moments of a supernova caught in visible light.

Read about Chandra observing the supermassive black hole in galaxy Pictor A having a little meal.

You can find out more about the work of NASA here

Learn more about the past and future plans of the ESA

Take the space voyage of the Hubble Space Telescope here

Learn more about irregular dwarf galaxies

Read a paper on the star formation history of irregular dwarf galaxy UGC 4879 here.


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