http://nuclear718.blogspot.tw/2011/01/2012.html



星期一, 1月 24, 2011






2012兩個太陽？（參宿四星要爆炸了）










最近比較忙，所以幾乎沒有多餘的時間寫部落格，但昨天看到一則天文相關的新聞，由於太過神奇，所以一定要和大家分享...................



先拋棄所有的天文術語，我試著用最簡單的語言描述這事件：夜空中，有一顆非常巨大的星星，他的中文名字叫做參宿四星，有多大呢？直徑是我們太陽的一千多倍！由於這顆星星已經到了壽命的末期，幾年前被天文學家觀察到他的體積正快速的縮減中，而體積縮減通常就是這種巨星即將壽終正寢的跡象。這顆星星會在斷氣的最後一刻，引發一場天文上的華麗煙火秀，許多新聞宣稱會在白天形成兩顆太陽的場景，或者，將會使得晚上亮得像白天，這樣類似科幻片的景色將會持續數周之久。
 



我看到新聞後，雖然很興奮的轉貼到臉書上分享，但是因為擔心這又是一場記者的烏龍新聞，又上了國外網站找相關的報導，也聽了一些說法，事實上以現有的技術，對於這起太空煙火秀的時間點預測是有問題的，因為恆星演化的生命週期是以億年為單位，以人類的天文技術，能夠確定參宿四星現在確實處於生命的末期，但這個『末期』很有可能還會持續數百萬年，相較於以億為單位的時間尺度，假如能夠預測其將在一百萬年內發生大爆炸，已經是非常精準了！所以，新聞報導提到有『天文研究』預測將在今年或明年發生大爆炸，這樣的預測說法恐怕是太大膽了點！（～失望）



另一個關於亮度的說法也是有問題的，若真的發生爆炸，對其亮度最亮的預測也不過與滿月相當，要達到『兩個太陽』的場景，恐怕只是為了新聞的宣染力。（～失望again）



許多『2012世界末日迷』把這個事件和他們堅信不已的2012牽連在一起，認為這樣大爆炸將會摧毀地球。

好吧！也許那篇預測這一、兩年會發生爆炸的『天文研究』是真的，但這樣一場發生在600多光年外的爆炸，實在難以撼動地球。600多光年是非常不可思議的遠距離，連光都要跑640年的距離！

畢竟我也不是這一行的專家，所以我就不在此辯駁像這類超新星爆炸時，究竟會不會有大量的咖馬射線破壞地球上空的電離層，導致後續的太陽、宇宙輻射抵達地球表面，致使生靈塗碳。我們可以反過來用一個事實來看這個末日問題，其實過去的歷史裡已經發生過很多起超新星爆炸，最早的紀錄出現在『後漢書：天文志』。宋朝時還觀察到了人類有史以來所見過最亮的超新星爆炸，《宋史·天文志》卷五六中記載為：「景德三年四月戊寅，周伯星見，出氐南，騎官西一度，狀如半月，有芒角，煌煌然可以鑒物，歷庫樓東。八月，隨天輪入濁。十一月復見在氐。自是，常以十一月辰見東方，八月西南入濁。」現代天文學家估計其亮度應該超過弦月，其實這樣的估計，與參宿四星大爆炸的亮度預測是接近的。古今中外的歷史裡，已經有過多起的超新星爆炸觀測記錄，距估計銀河系裡每五十年就會發生一次，光是人類這個物種存在地球的時間就長達數百萬年了，所以要說這樣的事情會導致地球上的生物大滅絕，實在有點言過其實（住在地球上的生物一天到晚要大滅絕，會不會太忙了一點？）。



文章裡的主角，參宿四星究竟在夜空中的什麼地方呢？

這個問題問我就對了，雖然我從小是個星座白痴，因為我認為隨便都可以找三顆星星連成夏季大三角（真是個很爛的定義），多找幾顆星星，還可以連得出各種形狀，盡管我的辨識能力很有問題，但有一個星座我一定不會認錯-------『獵戶座』，參宿四星就是組成獵戶座的其中一顆明亮的星星，底下插圖裡我用紅色箭頭標示：
 






 
 









    
 

http://teacherknowledge.wikispaces.com/Life+cycle+of+a+star

 Life cycle of a star

 

Title: Life Cycle of a Star: It's a boy? It's a girl? It's a star!!



Overview & Learning Performances: Students will be grouped into teams of 3-5, and will investigate and present one of the following life cycles for a particular sized star. Students will learn about how stars are arranged on the H-R Diagram, and what criteria are used.


Stellar Nebula- first stage in the life of all stars



Average (Sun-like) Star Life Cycle

	
Red giant

	
Planetary Nebula

	
White dwarf

	
Black dwarf



Huge Star Life Cycle

	
Red Supergiant

	
Supernova*

	
Neutron Star



Giant Star Life Cycle

	
Red Supergiant

	
Supernova

	
Black Hole*



 





*As a class in other lessons, the last two stages will be covered:

	
	
Supernova (for stars at least five times as big as our sun)

	
	
Black hole (for stars at least five times as big as our sun)



Students should make sure to include in their report:



Where the star falls in the H-R diagram

	
	
Luminosity

	
	
Magnitude

	
	
Surface temperature

	
	
Age

	
	
Size



Images of the star in each stage

	
	
Defining characteristics

	
	
How to identify it



 




Assessment:

The student groups will find a creative and innovative way to present their star lifecycle stages to the class. Different types of presentations could be:

VH1 version of "The life of a Star- No Not the Hollywood kind" in which a commentator and paparazzi follow the "star" through their life and highlight controversial or exciting moments in their life.

A scrapbook of the stars life with main points highlighted, and pictures of the important moments

A rap or other song with new lyrics that use the information and facts

Any other approved method



I will prepare a rubric ahead of time and review the criteria for success with the students before the presentation.



Although all students will not personally be researching all of the topics themselves, they will be responsible for putting the stage of the life cycle they researched into their Guide to the Universe, along with one stage from at least one other group.


Sources:

http://archives.cnn.com/2000/fyi/news/04/26/supernova.lp/



Rationale: I decided to teach students about the life cycle of a star in the form of group projects because the theory of social constructivism states that students who are in groups will learn better as they learn from their peers and are able to teach each other and discover their misconceptions as a team. Also, group presentations are important for the students to practice their oral and public speaking skills.


Link to Unit: This lesson is necessary for the students to travel around the universe because one of the things they will mainly see are stars. However, since stars are so diverse and have so many stages of their life, it's important for the students to know what they are observing when they see it out their viewing window. Since the students have to put at least four of the six stages in their handbook, this lesson will be a good opportunity for students to see what stages are the most interesting to them, and they can choose to report on those and become experts as they engage in a peer teaching moment.




Link back to Unit Plan