# Talk:Solar mass

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## (Mass of Protostar?)

(nonrandom heading inserted ... said: Rursus (bork²) 08:54, 12 March 2009 (UTC))

How Do Find Solar Mass For Protostar?

Thank You.

-Mike

A few points-

There are many ways of calculating the mass of our Sun. I suggest adding a few more equalities, complete with derivations or explanations. The derivations are very important, especially for those not familiar with the subject matter.
Yes, the Solar Mass does persist as "one of astronomy's ... historical conventions," but it is highly useful because it is so easy to visualize compared to many other celestial masses and is therefore a convention that should stick, at least until we find a more useful one. I would hardly call it an "arcane" convention.
It is possible to write a mass as a length through the tools of General Relativity, but it is at best occasionally useful or worthwhile. I suggest making note of this in the article instead of listing it as "common."

Prometheusindisguise (talk) 23:44, 19 January 2009 (UTC)

Re: the "arcane" thing. "solar mass" is used everyday in the peer-reviewed astronomy primary literature, so it doesn't count as arcane in the old-fashioned sense; moreover, "solar mass" is an easy to visualize quantity, so it's not arcane in the esoteric sense either. Besides, the sentence contradicts the first sentence of the article that says the solar mass is a "standard" unit. Therefore, I'm going to delete that whole sentence. Sorry.Warren Platts (talk) 02:19, 30 January 2009 (UTC)

## Conventional vs. actual?

Ehhm, it occurred to me that if the Solar mass is used as a nonstandard unit, the size of that unit quantity should be separate from the actual Solar mass, like the metre is standardized on an obsolete value of Earth radius. But that is a scientific ideal, which may or may not be implemented in reality (keeping in mind the science-philosophical and linguistic sloppyness of the current weird IAU definition of planet). So, now:

• is the conventional unit "Solar mass" fixed?
• or does it bounce around randomly depending on the measurements of the actual Solar mass?

If the earlier, the article should be structured acc2 that there are two "Solar mass" concepts. ... said: Rursus (bork²) 08:54, 12 March 2009 (UTC)

The Solar mass would only change if the gravitational constant (G) changed. The quantity G*M(sun) is known highly accurately from measurement of the orbital parameters of the planets. The value for G is known only to a few significant figures and as such the mass of the sun is only known to roughly the same precision. Unlike the meter, which is now defined in terms of the speed of light (a constant) and a time (a certain number of oscillations of cesium), the suns mass is effectively defined by the standard gravitational parameter (a measured value) and the gravitational constant (another measured value). So, to answer your questions: no, and kind of. 68.197.129.9 (talk) 23:12, 31 March 2009 (UTC)

The Solar mass is continually decreasing; about 4 million tons per second due to nuclear fusion, and about 2 million tons per second due to the solar wind. This is negligible compared to the total solar mass for short-term calculations. --IanOsgood (talk) 05:41, 8 July 2009 (UTC)

## Stub

Wikipedia:Stub category applies to those articles with no more than "rudimentary" information.

While very short articles are likely to be stubs, there are some subjects about which there is very little that can be written.

This article is not a stub, there's just not much more that should be written, more could, but it would be "inflation" for the sake of it. If you really think it can never be more than a stub, then {{Copy to Wiktionary}}. HarryAlffa (talk) 11:24, 21 September 2009 (UTC)

There's quite a bit more that can be written about it, like how the mass was determined, why is the value in this article that way, how it is used, etc. It's like the kilogram article, there is something more to say. 76.66.197.30 (talk) 04:42, 23 September 2009 (UTC)

## Use of solar symbol ☉

I'm just curious where it is written that the symbol for the Sun should be written '☉'. It doesn't appear to be an IAU standard even though it is a common astronomical convention. Is there a style guideline somewhere suggesting it's use? Why not simply MSun? Thanks.—RJH (talk) 22:10, 6 October 2009 (UTC)

You could do that (subscript Sun or even subscript S), but when writing on paper I always use the ☉ (as a subscript, which is sometimes not available in electronic formatting). I do the same with the Earth symbol. Both of those go back to ancient times, I think, so they represent a historical convention. Both are little-used outside astronomy ... which is a rather narrow field ... so in a lot of electronic presentations I don't have them available. Since the symbol is used for nothing else, it does make for a certain relief from possible ambiguity. BSVulturis (talk) 15:26, 14 April 2010 (UTC)

## R☉/M☉

Hi, if M☉ is solar masses what is R☉ used in the illustration, maybe this could be added to the Related Units section? Regards Khukri 12:26, 16 February 2010 (UTC)

I'm guessing that R☉ might be the radius of the sun, but that's just a speculation, someone will need to confirm. 71.113.48.83 (talk) 07:44, 11 March 2010 (UTC)
Yup, that's Solar radius. BSVulturis (talk) 15:27, 14 April 2010 (UTC)

## Please fix problem causing Yahoo to say that this article says the sun is only slightly over 2000 kg

"Solar mass - Wikipedia, the free encyclopedia

"Related units|See also|References|Further readingThe solar mass (), 1.98892×1030 kg, is the standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies. It is equal to the mass of the Sun, about two...

"en.wikipedia.org/wiki/Solar_mass - Cached"

Note that the 1030 appears as though it were a four digit number equal to 1.03*10^3. Of course, 1.98892 times 1,030 kg is between 2000 kg and 2100 kg and is not really the mass of the sun!

In the actual article, the 30 is a superscript, but it does not display that way in the Yahoo search engine.

If no better solution can be found, this could be fixed by changing the article to say 10^30 with a ^ symbol so that it is clearly an exponential and not a four digit number.

However, I would prefer for the article to continue to look as it does now.

Is there any way to change the article so that it appears as 10^30 in search engines that do not display superscripts, but continues to appear as it does now in Wikipedia?

71.109.155.162 (talk) 17:30, 24 November 2010 (UTC)

That is up to Yahoo or Google to fix. 89.217.9.188 (talk) 18:27, 16 January 2015 (UTC)

## Value according to sources

Currently, there are two sources cited,

the first source specifies the solar mass parameter to ${\displaystyle GM_{\odot }=1.32712442099\cdot 10^{20}m^{3}s^{-2}}$ and Newton's gravitational constant to ${\displaystyle G=(6.67428\pm 0.00067)\cdot 10^{-11}m^{3}kg^{-1}s^{-2}}$ whereas NIST CODATA's value for G is ${\displaystyle G=(6.67384\pm 0.00080)\cdot 10^{-11}m^{3}kg^{-1}s^{-2}}$.

Apparently the value in this article uses the first source's definition of the solar mass parameter and NIST's value for G to calculate the solar mass:

${\displaystyle M_{\odot }={\frac {(GM_{\odot })}{G}}={\frac {1.32712442099\cdot 10^{20}m^{3}s^{-2}}{6.67384\cdot 10^{-11}m^{3}kg^{-1}s^{-2}}}=1.98855\times 10^{30}kg}$

Is there any particular reason or intention why NIST's value for G is used instead of the one from ASA? In my opinion, using the last one would be more consistent than jumping around between different sources with different G values for the same calculation.

2x² (talk) 15:08, 6 October 2014 (UTC)

I'm sorry for editing my previous post but I had confused myself and by mistake used a different formula in the demonstration than I calculated the result with. Nevertheless, this didn't change anything about my remark.
Thus I'd like to suggest to use for ${\displaystyle G}$ the value given by the same source as the ${\displaystyle GM_{\odot }}$ value, namely the one given in the ASA file:
${\displaystyle {\begin{array}{rcl}GM_{\odot }&=&1.32712442099\cdot 10^{20}m^{3}s^{-2}\\G&=&(6.67428\pm 0.00067)\cdot 10^{-11}m^{3}kg^{-1}s^{-2}\end{array}}}$
This would yield the following value for the solar mass:
${\displaystyle M_{\odot }={\frac {1.32712442099\cdot 10^{20}m^{3}s^{-2}}{6.67428\cdot 10^{-11}m^{3}kg^{-1}s^{-2}}}\approx 1.98842\times 10^{30}kg}$
the uncertainty of which can be obtained by the usual taylor expansion:
${\displaystyle \Delta M_{\odot }=M_{\odot }{\sqrt {\left({\frac {\Delta (GM_{\odot })}{(GM_{\odot })}}\right)^{2}+\left({\frac {\Delta G}{G}}\right)^{2}}}\approx 0.00020\times 10^{30}kg}$
Any comments on this are appreciated. If there will again be no reply within a few weeks, I'll proceed on the assumption that there is no disagreement with my suggestion and change the article.
2x² (talk) 21:00, 14 November 2014 (UTC)

## Caption not understandable, Betelgeuse too big?

In the caption to the first diagram:

The Sun (1 M☉) which is not visible in this thumbnail is included to illustrate the scale of example stars.

There is something wrong with this sentence. If the sun is not visible, then in what sense is it included, and how can it illustrate anything? (Indeed, the sun is not visible, either in the thumbnail or in the full-size version of the picture.)

Also, how can Betelgeuse, at 20 solar masses, have a radius that exceeds the earth's orbit? This seems to be wrong by many factors of 10. Or am I so dense? 89.217.9.188 (talk) 18:38, 16 January 2015 (UTC)

Betelgeuse is a red giant star, a different part of a star's evolution than the Sun. While the masses can be compared at any stage of stellar evolution, the radii cannot be compared. — Preceding unsigned comment added by 171.66.209.130 (talk) 17:07, 25 February 2015 (UTC)