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우주의 눈?…늙은 별 ‘최후의 숨결’ 포착 (나우뉴스 2012.07.26 20:07)

우주의 눈?…늙은 별 ‘최후의 숨결’ 포착

 

마치 우주에서 우리를 바라보는 듯한 눈동자를 닮은 우주 사진이 공개돼 화제가 되고 있다.

10일 영국 데일리메일에 따르면 이 사진은 죽어가는 늙은 별이 뿜어내는 최후의 숨결을 허블 우주망원경이 포착한 것이다.

기린자리(Camelopardalis)에 있는 이 별의 정식명칭은 ‘U Camelopardalis’로 줄여서 ‘U 캠(U Cam)’으로 불린다.

지구에서 약 1500광년 떨어진 U 캠은 이제 수명이 거의 다해 죽음을 향한 마지막 연료를 태우고 있는 불안한 상태다.

이 별의 핵에서 외피로 헬륨가스가 수천 년마다 주기적으로 폭발하고 있는데 가장 최근의 폭발로 가스가 분출된 모습이 마치 눈동자처럼 나타난 것이다.

U 캠은 산소보다 탄소를 더 많이 가진 탄소성(星)으로 우주에서도 몇 안 되는 별이다. 이는 별의 표면 중력이 매우 약해 강력한 항성풍이 불 때마다 많은 양의 탄소를 손실하기 때문이다.

천구의 북극 즉 북쪽 하늘에서 관찰할 수 있는 U 캠은 허블 망원경에 찍힌 사진보다는 실제 훨씬 작은 별이다. 사실 허블 사진 중앙에 작은 픽셀 하나로만 표현될 정도로 작다고 한다.

하지만 작은 크기에도 그 밝기는 다른 어떤 별과 비교해도 압도적으로 밝아 카메라의 수용체를 포화시킬 정도다.

따라서 모성보다 훨씬 크고 희미한 기체의 껍질이 허블의 사진에 자세히 나타났다.

이 현상은 종종 불규칙하고 불안정하지만 U 캠에서 방출된 기체의 껍질은 거의 완벽한 원형에 가깝다고 한다.

 

Eye in the sky: Hubble captures eerie 'cornea' staring at us from the cosmos - but it's actually the last breath of a dying star

By Rob Waugh

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Read more: http://www.dailymail.co.uk/sciencetech/article-2170958/Hubble-captures-bubble-gas-blasting-dying-star-nuclear-heart-burns-out.html#ixzz2VoQ4HZzl
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The Hubble Space Telescope has captured what looks like a human cornea staring at us from the cosmos, but it's actually one of the last 'breaths' of a distant, dying star.

The rings around the burning core 'bubble' of gas blasted out of a dying star clearly visible as its core begins to burn out.

The star, Camelopardis is nearing the end of its life - but is so far away that it would normally appear as a single pixel in an image of this size.

Every few thousand years, the star coughs out a nearly spherical shell of gas as a layer of helium around its core begins to fuse

Every few thousand years, the star coughs out a nearly spherical shell of gas as a layer of helium around its core begins to fuse

The Hubble Space Telescope has captured what looks like a human cornea staring at us from the cosmos, but it's actually one of the last 'breaths' of a distant, dying star.

The real thing: The Hubble Space Telescope has captured what looks like a human cornea staring at us from the cosmos, but it's actually one of the last 'breaths' of a distant, dying star.


But the brightness of the shell of gas erupting from its core means Hubble's sensors capture this spectactular image.

Camelopardalis, or U Cam for short, is a star nearing the end of its life. As stars run low on fuel, they become unstable. Every few thousand years, U Cam coughs out a nearly spherical shell of gas as a layer of helium around its core begins to fuse.

The gas ejected in the star’s latest eruption is clearly visible in this picture as a faint bubble of gas surrounding the star.

U Cam is an example of a carbon star, a rare type of star with an atmosphere that contains more carbon than oxygen. Due to its low surface gravity, typically as much as half of the total mass of a carbon star may be lost by way of powerful stellar winds.

 

Located in the constellation of Camelopardalis (The Giraffe), near the North Celestial Pole, U Cam itself is much smaller than it appears in this Hubble image.

In fact, the star would easily fit within a single pixel at the center of the image. Its brightness, however, is enough to saturate the camera's receptors, making the star look much larger than it is.
The shell of gas, which is both much larger and much fainter than its parent star, is visible in intricate detail in Hubble’s portrait. This phenomenon is often quite irregular and unstable, but the shell of gas expelled from U Cam is almost perfectly spherical



Read more: http://www.dailymail.co.uk/sciencetech/article-2170958/Hubble-captures-bubble-gas-blasting-dying-star-nuclear-heart-burns-out.html#ixzz2VoQILI1z
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