来自ESO（欧洲南方天文台）官方网站 8月24日
www.eso.org
© ESO Public Affairs Department
本人翻译
http://www.eso.org/outreach/press-rel/pr-2005/phot-26-05.html
Celestial Blast in Bleak Reticulum
The southern Reticulum constellation certainly isn't a big hit for amateur astronomers. This tiny, bleak and diamond-shaped constellation, not far on the sky from the Large Magellanic Cloud, is often overlooked. But recently, astronomers had a closer look at a galaxy situated inside it. And more precisely at an exploding star hosted by the spiral galaxy NGC 1559 .
对于业余爱好者们，南天的网罟座的确不吸引眼球。这个小而黯淡、在天球上离大麦云不远的钻石状星座，常常被人小瞧了。但是最近，天文学家们对坐落其中的一个漩涡星系NGC 1559 进行了一番仔细观察，并且更加精密地观测了其中一颗爆发的恒星。
On the night of August 4, 2005, Australian amateur astronomer Reverend Robert Evans discovered a supernova just North of the galaxy with his 0.31-m telescope. The supernova - the explosion of a star - was of magnitude 13.8, that is, only 20 times fainter than the entire host galaxy. Being the 104th supernova discovered in 2005, it received the name SN 2005df. Noticeably, Evans had already discovered 2 other supernovae in the same galaxy: in 1984 (SN 1984J) and in 1986 (SN 1986L).
在2005年8月4号夜间，澳大利亚的天文爱好者Reverend Robert Evans用他的0.31米望远镜在该星系正北部分发现了一颗超新星。这颗超新星——爆发的恒星——目视星等为13.8等，也就是说，达到了宿主星系总亮度的1/20。作为2005年发现的第104颗超新星，它得到编号SN 2005df。值得注意，Evans在同一星系中已经发现了另外2个超新星：SN 1984J 和 SN 1986L。
The following night, astronomer Marilena Salvo and her Australian colleagues classified the supernova as a somewhat unusual type Ia supernova, caught probably 10 days before it reached its maximum brightness. Such a supernova is thought to be the result of the explosion of a small and dense star - a white dwarf - inside a binary system. As its companion was continuously spilling matter onto the white dwarf, the white dwarf reached a critical mass, leading to a fatal instability and the supernova.
第二天夜里，天文学家Marilena Salvo 和她的澳大利亚同事们发现，这颗超新星属于比较罕见的Ia型，很可能是在达到最大亮度前10天被捕获的。这一类超新星被认为是双星系统内的一颗小而致密的恒星——白矮星——的爆发所致。随着它的伴星持续地向它转移物质，这颗白矮星达到一个临界质量，导致最终致命的不稳定，就成了超新星。
These are exactly a kind of supernovae in which Dietrich Baade, Ferdinando Patat (ESO), Lifan Wang (Lawrence Berkeley National Laboratory, USA), and their colleagues are interested. In particular, they study the polarization properties of this kind of supernova in order to learn more about their asphericity, which holds important clues to the detailed physics that governs this terminal catastrophe in the life of such stars.
这类超新星恰好就是欧南台的Dietrich Baade、Ferdinando Patat 和美国劳伦斯伯克莱国家实验室的Lifan Wang 所感兴趣的对象。他们主攻的目标是研究这类超新星的极性，以了解其非球对称特征。在执掌这类恒星最终毁灭命运的物理机制中，这种非球对称性占据着重要的线索地位。
Having an accepted observing programme that uses the FORS1 multi-mode instrument on Kueyen, one of the four Unit Telescopes of ESO's 8.2m Very Large Telescope at Cerro Paranal, they triggered a Target of Opportunity request so that on-duty astronomers at the VLT could observe this supernova, which was done on August 6.
这一小组手已经得到批准使用甚大望远镜之Kueyen号上的FORS1（缩焦器与低离差摄谱仪？），于是他们启动了一次偶发天体观测申请（？），这样当时值班的天文学家就可以观测这颗超新星。观测完成于8月6号。[此段文字翻译得甚是蹩脚]
From a very first analysis of their data, Wang and his colleagues found that SN 2005df resembles closely another supernova they had studied before, SN 2001el, whose explosion they showed was significantly asymmetric (see ESO PR 23/03).
从最初的数据分析中，Wang和同事发现，这颗超新星SN 2005df与他们以前研究过的一个，SN 2001el，十分相似。2001el 的爆发就是明显不对称的。详情参见此处
NGC 1559 is a SBc(s)-type spiral galaxy located about 50 million light-years away, that weighs the equivalent of about 10,000 million of suns, and is about 7 times smaller than our Milky Way: on the sky, it measures about 4x2 arcmin2. Receding from us at a speed of about 1,300 km/s, it is a galaxy of the Seyfert type. Such galaxies are characterized by a bright nucleus that radiates strongly in the blue and in the ultraviolet. Astronomers think that about 2 solar masses of gas per year are transformed into stars in this galaxy. Like most galaxies, NGC 1559 probably contains a black hole in its centre, which should have a mass that is equivalent to 300,000 suns.
NGC 1559 是一个SBc(s) 型旋涡星系，距离约5千万光年远。质量大约是太阳质量的100亿倍，大约是银河系的1/7。在天球上，它大约呈4'x2'大小。它以大约1300千米/秒的速度退行。这是一个塞弗特星系，特征是有一个在蓝光和紫外线波段强烈辐射的明亮核心。天文学家认为，这个星系中的气体以每年2个太阳质量的速率形成恒星。和大多数星系一样，NGC 1559 也有可能包藏了一个黑洞。如果的确如此，这一黑洞的质量应该在300,000个太阳质量上下。
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注：SBc galaxies are characterized by the presence of stars and HII regions in the bar and spiral arms, by the near absence of a nuclear bulge, and the openness of the spiral pattern. The "(s)" indicates that the spirals are attached to the ends of the bar.
SBc 星系的特征是棒和旋臂中存在大量恒星和HII区域，几乎没有核球的隆起，还有开放的旋臂外观。(s)表示旋臂紧连在棒的两端。 |
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