View Full Version : The Sun as an Average Star ...

2006-Feb-27, 04:09 AM
The Sun is sometimes described as a middle-aged, average, main sequence star. Is that true? What is the average star really like? What would you expect of other stars like our own sun? What is you intake on this?

2006-Feb-27, 04:38 AM
What kind of average?

NASA: Outreach: Sun-Earth Misconceptions (http://pwg.gsfc.nasa.gov/istp/outreach/sunearthmiscons.html)

The Sun is an average star... This depends on how you define "average." On the absolute scale of the size of active stars from largest to smallest, our Sun is about medium mass and girth. But when you consider that most of the universe is made up of dying, shrinking dwarves, our Sun is actually larger, hotter, more massive, and brighter than the vast majority of all stars.

See this article (http://www.bautforum.com/showthread.php?p=145890#post145890), and onward, in topic: which kind of star has the longest life expectancy.

2006-Feb-27, 05:19 AM
The sun is classified as a middle-aged, average, main sequence star because it falls in to the technical definitions of the various kinds of stars. In reference to the sun being middle aged, you have to look at the life span of a star. The bigger the star, the shorter the life span of it. According to studies the Sun is about 5 billion years old. In comparison to other stars its size that have expired, it should die out around 10 billion years, making the Sun middle aged. The Sun is also said to be average. Average for a star is based on its luminosity or brightness. In comparison to other stars in the galaxy, the Sun is said to be of a typical luminosity. Characteristics of Main Sequence stars are that they use fusion, are stable (cannot get smaller or larger in size) and have a strong gravitational pull. The Sun fits the bill for this as well, making it a main sequence star.

2006-Feb-27, 04:25 PM
The Sun is also comparatively metal-rich for its category of star, which is good news for us (though keep in mind that to an astronomer a "metal" is anything that's not hydrogen or helium).

2006-Feb-27, 07:51 PM
The most numerous stars seem to be red dwarfs (http://www.spacedaily.com/reports/Study_Shows_Most_Milky_Way_Stars_Are_Single_Red_Dw arfs.html). Our nearest neighbor, Proxima Centauri, is one.

Therefore, these will make the Sun less average if you base the average on just the number of stars. If brown dwarfs are many, "the average sun" becomes even less average. [Added: Many consider brown dwarfs to be sub-stellar as they fuse only deuterium and for a short period only.]

2006-Mar-07, 11:03 PM
Moved to Q&A section.