跳转到内容

File:The peculiar asymmetry of NGC 949.jpg

页面内容不支持其他语言。
這個文件來自維基共享資源
维基百科，自由的百科全书

原始文件 （1,280 × 1,290像素，文件大小：384 KB，MIME类型：image/jpeg）

摘要

描述
English: This image provides the clearest ever view of galaxy NGC 949, which lies over 30 million light-years away in the constellation of Triangulum. The galaxy has an unusual shape, made more obscure due to its inclination. From our point of view, it is difficult to discern exactly what type of galaxy NGC 949 is, but it is certainly a disc galaxy of some kind, most likely a spiral.

NGC 949 was first discovered by Sir William Herschel on 21 September 1786, using an 18.7-inch reflecting telescope. The galaxy was one of about 3000 objects Herschel catalogued as "nebulae" during an intense and systematic deep sky survey, the results of which eventually formed the bulk of the New General Catalogue (NGC).

Taken with Hubble’s Advanced Camera for Surveys (ACS), this new image shows extraordinary detail. This detail allows us to see a strange asymmetric alignment in the dark lanes of dust that snake across the galaxy. The top-right half of the galaxy appears considerably more marbled with dust in this image; a curious observation explained by stars tending to favour locations towards the centre of a galaxy, and dust preferring almost invariably to reside along the galactic plane.

When a galaxy is inclined as NGC 949 is, some regions — in this case the top-right — are tipped towards us and the light from the stars we see in these regions has had to travel through more dust. This causes the light to appear redder — the result of the same process that gives the sun’s light a red hue at dusk — or else disappear entirely, making the dust appear more prominent on that side of the galaxy.

In the part tipped away from us, the light from the stars has had to pass through much less dust to reach us, so it appears brighter, and the dust is much less prominent.

Were it possible to view NGC 949 from the opposite side, the apparent alignment of the dust would be reversed.

The scientific advantages of this effect were recently displayed in suitably stunning style in the M31 PHAT mosaic, which allowed astronomers to produce a partial three-dimensional dust map of M31 four times clearer than any previously attempted.
日期
来源 http://www.spacetelescope.org/images/potw1518a/
作者 ESA/Hubble & NASA

许可协议

w:zh:知识共享
署名
署名
 ESA/Hubble images, videos and web texts are released by the ESA under the Creative Commons Attribution 4.0 International license and may on a non-exclusive basis be reproduced without fee provided they are clearly and visibly credited. Detailed conditions are below; see the ESA copyright statement for full information. For images created by NASA or on the hubblesite.org website, or for ESA/Hubble images on the esahubble.org site before 2009, use the {{PD-Hubble}} tag.
Conditions:
  • The full image or footage credit must be presented in a clear and readable manner to all users, with the wording unaltered (for example: "ESA/Hubble"). Web texts should be credited to ESA/Hubble (except when used by media). The credit should not be hidden or disassociated from the image footage. Links should be active if the credit is online. See the usage rights Q&A section on the ESA copyright page for guidance.
  • ESA/Hubble materials may not be used to state or imply the endorsement by ESA/Hubble or any ESA/Hubble employee of a commercial product or service.
  • ESA/Hubble requests a copy of the product sent to them to be indexed in their archive.
  • If an image shows an identifiable person, using that image for commercial purposes may infringe that person's right of privacy, and separate permission should be obtained from the individual.
  • If images or visuals are changed significantly from the original work (apart from resizing, cropping), we suggest that the changes are mentioned after the credit line. For example "Original image by ESA/Hubble (M. Kornmesser), warping and recolouring by NN".

Notes:

  • Note that this general permission does not extend to the use of ESA/Hubble's logo, which shall remain protected and may not be used or reproduced without prior and individual written consent of ESA/Hubble.
  • Also note that music, scientific papers and code on the esahubble.org site are not released under this license and can not be used for non-ESA/Hubble products.
  • By reproducing ESA/Hubble material, in part or in full, the user acknowledges the terms on which such use is permitted.
w:zh:知识共享
署名
本文件采用知识共享署名 4.0 国际许可协议授权。
署名: ESA/Hubble
您可以自由地：
  • 共享 – 复制、发行并传播本作品
  • 修改 – 改编作品
惟须遵守下列条件：
  • 署名 – 您必须对作品进行署名，提供授权条款的链接，并说明是否对原始内容进行了更改。您可以用任何合理的方式来署名，但不得以任何方式表明许可人认可您或您的使用。

说明

添加一行文字以描述该文件所表现的内容

此文件中描述的项目

描繪內容

資料大小

393,163 字节

高度

1,290 像素

寬度

1,280 像素

多媒體型式

image/jpeg

核對和

a2e0900f4db7040a17a95dd2d0836d956ff71ec7

确定方法：​SHA-1

文件历史

点击某个日期/时间查看对应时刻的文件。

日期/时间缩⁠略⁠图大小用户备注
当前2015年6月8日 (一) 16:512015年6月8日 (一) 16:51版本的缩略图1,280 × 1,290（384 KB）JmencisomUser created page with UploadWizard

以下页面使用本文件：

全域文件用途

以下其他wiki使用此文件：

元数据

此文件中包含有扩展的信息。这些信息可能是由数码相机或扫描仪在创建或数字化过程中所添加。

如果此文件的源文件已经被修改，一些信息在修改后的文件中将不能完全反映出来。

检索自“https://wikicn.playgoteam.workers.dev/wiki/File:The_peculiar_asymmetry_of_NGC_949.jpg”