Talk:Solar apex/Archive 1

Archive 1

Inconsistency relating to Solar Apex?

The Milky Way page says "The apex of the Sun's way, or the solar apex, is the direction that the Sun travels through space in the Milky Way" and also "... 220 km/s ..."

The Solar Apex page says "The solar apex, or the Apex of the Sun's Way, refers to the direction that the Sun travels with respect to the Local Standard of Rest" and also "... 220 km/s ..."

The local standard of rest page says "... 255 km/s ..."

Should the first state more clearly "relative to the Local Standard of Rest"? And what's the correct orbital speed? — Preceding unsigned comment added by Captainunderpants (talk • contribs) 22:38, 22 January 2018 (UTC)

Question

Re: "...discussions regarding the solar passage through the arms of the Galaxy..."

Am I missing something or is this just wrong?

it seems logical that the sun is a member of a galactic arm and not just visiting; otherwise galactic arms would not form; only a random scattering of objects would exist. It's like suggesting that planets regularly pass through solar systems rather then belonging to them.

The arms are in fact not made of material (stars and gas), but are dynamic phenomena of density and/or brightness. See Density wave theory. So the sun does move thru them. ★NealMcB★ (talk) 16:33, 15 September 2018 (UTC)

Discrepancy ?

There is a factor of ten discrepancy in this article between the reported orbital speed of solar system and that of neighboring stars: "orbital speed is 217 km/s" and "...is always between 20 and 25 km/s for the Sun's neighbours". (unsigned)

No discrepancy. Sun is moving 'slowly' relative to neighbours, with them all orbiting the galactic centre at over 200 km/s. - Rod57 (talk) 16:38, 30 October 2017 (UTC)

Spiral arms

The spiral arms are regions of enhanced gas density, leading to enhanced star formation and hence many more young, hot (and therefore luminous and blue) stars than other parts of the galactic disk. This is what gives the arms their prominence, but it doesn't mean that there aren't stars between the arms (there are many, just older and so there are no luminous blue stars, hence not so visible). Also, the stars orbit at a different rate to the arms and regularly pass through them. Our sun happens to be close to the edge of an arm, but I don't think we're in one. 152.78.192.216 17:54, 23 October 2007 (UTC)

Other

This article was pretty much wrong! The local standard of rest is very important in this respect. Cheers, Jeffrey --82.136.242.69 (talk) 11:17, 22 January 2009 (UTC)

Is it just me or shouldn't the sun have reached Vega already? The Earth is roughly 4.5 billion years old and if we assume the sun is at least as old and have been in movement since then, the 16.5km/s would have had it travel the 25 light-years to Vega by now. Quite some time earlier, even. — Preceding unsigned comment added by 109.58.48.18 (talk) 14:22, 1 November 2011 (UTC)

I feel like you are assuming that the sun formed at the distance from Vega that it is now, as opposed to only being this close now because it has been moving in that direction for a few billion years. Darryl from Mars (talk) 01:30, 19 June 2012 (UTC)

Sources and consensus

The article gives very precise values for the direction and speed of the Sun. But the source of this information is not given.

The motion of the Sun to its apex is the motion w.r.t. the stars in its neighbourhood; more precisely the "Local Standard of Rest", that is the motion superimposed on the orbital motion around the center of the galaxy, that it shares with the stars in its vicinity.

In fact in literature there are wildly different estimates for both the ideal (or average) circular orbit around the Milky Way at the location of the Sun, and of the velocity vector of the Sun w.r.t. this LSR. Some recent publications (check the tables in the introduction listing results from various authors):

http://adsabs.harvard.edu/abs/2009NewA...14..615F

http://adsabs.harvard.edu/abs/2010MNRAS.403.1829S

http://adsabs.harvard.edu/abs/2011MNRAS.412.1237C

From the velocity components of the first (U=+7.5 km/s, V=+13.5 km/s, W=+6.8 km/s) I compute for the apex: l=61°, b=+24° = RA=271° = 18:05, DEC=+35°

Tom Peters (talk) 21:03, 17 March 2013 (UTC)

I agree that the data is in need of proper citation. From the following reference:

Zombeck, Martin V. (2007), Handbook of Space Astronomy and Astrophysics (3rd ed.), p. 39, ISBN 978-0-521-78242-5

I get (α = 271°, δ = 30°); velocity 19.7 km/s. Praemonitus (talk) 18:43, 23 May 2021 (UTC)