Discovered in 1784 by the German–British astronomer William Herschel, NGC 4394 is a barred spiral galaxy situated about 55 million light-years from Earth. The galaxy lies in the constellation of Coma Berenices (Berenice's Hair), and is considered to be a member of the Virgo Cluster. NGC 4394 is the archetypal barred spiral galaxy, with bright spiral arms emerging from the ends of a bar that cuts through the galaxy’s central bulge. These arms are peppered with young blue stars, dark filaments of cosmic dust, and bright, fuzzy regions of active star formation. At the centre of NGC 4394 lies a region of ionised gas known as a LINER. LINERs are active regions that display a characteristic set of emission lines in their spectra— mostly weakly ionised atoms of oxygen, nitrogen and sulphur. Although LINER galaxies are relatively common, it’s still unclear where the energy comes from to ionise the gas. In most cases it is thought to be the influence of a black hole at the centre of the galaxy, but it could also be the result of a high level of star formation. In the case of NGC 4394, it is likely that gravitational interaction with a nearby neighbour has caused gas to flow into the galaxy’s central region, providing a new reservoir of material to fuel the black hole or to make new stars.

Hubble’dan İnciler

Discovered in 1784 by the German–British astronomer William Herschel, NGC 4394 is a barred spiral galaxy situated about 55 million light-years from Earth. The galaxy lies in the constellation of Coma Berenices (Berenice's Hair), and is considered to be a member of the Virgo Cluster.  NGC 4394 is the archetypal barred spiral galaxy, with bright spiral arms emerging from the ends of a bar that cuts through the galaxy’s central bulge. These arms are peppered with young blue stars, dark filaments of cosmic dust, and bright, fuzzy regions of active star formation. At the centre of NGC 4394 lies a region of ionised gas known as a LINER. LINERs are active regions that display a characteristic set of emission lines in their spectra— mostly weakly ionised atoms of oxygen, nitrogen and sulphur.  Although LINER galaxies are relatively common, it’s still unclear where the energy comes from to ionise the gas. In most cases it is thought to be the influence of a black hole at the centre of the galaxy, but it could also be the result of a high level of star formation. In the case of NGC 4394, it is likely that gravitational interaction with a nearby neighbour has caused gas to flow into the galaxy’s central region, providing a new reservoir of material to fuel the black hole or to make new stars.

Hubble, aradan geçen pek çok yıl sonra bile hâlâ bize bir şeyler öğretiyor. Teleskop takımı çizgili sarmal bir galaksinin fotoğrafını tweetledi. Bu galaksi yeni değil, 1784 yılında Alman-İngiliz gökbilimci William Herschel tarafından keşfedilmişti.

NGC 4394, Dünya’dan yaklaşık 55 milyon ışık yılı ötede ve Başak Kümesi’nde bulunuyor. Coma Berenices (Berenice’nin Saçı) takımyıldızının içinde yer alıyor.

Çizgili sarmal bir galaksi ne demek? NASA açıklıyor:
NGC 4394’ün merkezinde, düşük iyonlaşma nükleer salım hattı bölgesi (LINER) olarak bilinen iyonlaşmış bir gaz bölgesi bulunuyor. LINER’ler, tayflarında bir dizi salım çizgisi özelliği gösteren etkin bölgelerdir ve çoğunlukla iyonlaşmış oksijen, nitrojen ve sülfür atomlarından oluşurlar.

 

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