Thursday, August 25, 2011

U Gem---Dwarf Nova

Detected the following object during a survey. Turn out it is U Gem, a known Dwarf Nova!

My observation:

5 MAG. VARIABLE V* U Gem -- Dwarf Nova
G0047E C2010 10 12.40190 07 55 05.23 +22 00 05.1 13.5 R H07
G0047E C2010 10 12.43542 07 55 05.22 +22 00 05.2 13.8 R H07
G0047E C2011 01 03.14072 07 55 05.23 +22 00 05.2 14.2 R H07
G0047E C2011 01 03.17569 07 55 05.19 +22 00 04.5 13.6 R H07
G0047E C2011 03 29.15891 07 55 05.21 +22 00 05.0 09.4 R H07
G0047E C2011 03 29.19247 07 55 05.25 +22 00 04.7 09.5 R H07

U Geminorum (U Gem), in the constellation Gemini, is an archetypal example of a dwarf nova. The binary star system consists of a white dwarf closely orbiting a red dwarf. Roughly every 100 days it undergoes an outburst that greatly increases its brightness. Discovered by J.R. Hind in 1855 during one of its outbursts, it has been continuously observed since.

The U Geminorum binary has a very short orbital period of 4 hours and 11 minutes; this orbit alone makes the system variable, as the components transit and eclipse each other with each revolution. Normally, the combined apparent magnitude varies between 14.0 and 15.1; during an outburst however, the star can brighten a hundredfold, to 9th magnitude. Though the average interval is 100 days, the period is in fact highly irregular, varying from as little as 62 days to as long as 257. As is the case with dwarf novae, the outbursts are theorized results of a periodic surge of influx from the white dwarf's accretion disk, caused by instability in the disk itself.

Distance estimates for U Geminorum have varied from 52 parsecs (170 light-years) to 112 parsecs (370 light-years), with a best estimate of 82 parsecs (270 light-years).[3]



Thursday, August 18, 2011

好少將文章過膠, 今日過左呢篇

好少將文章過膠, 今日過左呢篇: 我一向敬重畢非德, 但我認為今次他 made the wrong decision!




Sunday, August 07, 2011

Index

About life in general:


法網圖鑑﹕法律的局限
http://ashtheheaven.blogspot.com/2011/02/blog-post_19.html

周日話題﹕這是個不科學的時代
http://ashtheheaven.blogspot.com/2011/01/blog-post_30.html

歷史怎樣記載你?
http://ashtheheaven.blogspot.com/2011/03/blog-post_16.html

人生是沒有說明書的
http://ashtheheaven.blogspot.com/2009/05/blog-post_4646.html




Written for asteroids that I had named:


從困乏多情到博文約禮
http://ashtheheaven.blogspot.com/2010/12/blog-post_19.html

星的名字 錢不能買
http://ashtheheaven.blogspot.com/2010/11/blog-post.html

過客 ------「林超英」星
http://ashtheheaven.blogspot.com/2009_09_01_archive.html

天上人間系列之林青霞
http://ashtheheaven.blogspot.com/2006/03/blog-post_14.html

施永青星
http://ashtheheaven.blogspot.com/2008/12/blog-post_04.html

星(升)空夢
http://ashtheheaven.blogspot.com/2005/06/blog-post_111777631560620458.html