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van Maanen 2
It bugs me very much that the first star in van Maanen's list of two stars is called van Maanen 2. Controlled by SIMBAD – it's correct, oddly enough. Said:
Rursus☻ 18:15, 24 June 2008 (UTC)reply
But
this site lists this wd star as van Maanen 1, so someone got the numbers the other way. Said:
Rursus☻ 18:19, 24 June 2008 (UTC)reply
Yes it is a little odd. The name van Maanen 2 for this star dates back to at least 1943.
[1] Regards,
RJH (
talk) 01:53, 17 March 2012 (UTC)reply
Radial velocity
[2] follows the letter of the law, but is false. It is legal, but evil. If one is so concerned with sources, then search a good source for the radial velocity. It is a crying shame to claim +6 ± 15 km/s in one place, 60 km/s in another, and cite some silly approach-predicting paper with stupid calculations, given such mess and uncertainty on the radial velocity.
Incnis Mrsi (
talk) 15:55, 9 August 2012 (UTC)reply
The 60 km/s is not the radial velocity; it includes the transverse components of motion as well. Hence there is no contradiction unless the radial velocity is larger than 60. It looks like the radial velocity used in
García-Sánchez et al (2001) is based on
Greenstein and Trimble (1967).
Makarov (2004) assumes a radial velocity of –38 km/s, which is well outside the margin of error used in the García-Sánchez paper. You most likely have a point, but we should pull the sentence altogether rather than speculating. The derogatory nature of your remarks seems unnecessary. Regards,
RJH (
talk) 16:18, 9 August 2012 (UTC)reply
Yes, I made a mistake. I calculated the transverse component, it gives namely 60 km/s. We have figures: 1.237 ″/yr for right ascension and 2.709 ″/yr for declension. Since r.a. is almost 0 and its cosine is about 1, we can neglect the difference between spherical and Cartesian coordinates and apply Pythagoras' theorem, so we have about 2.978 ″/yr of angular transverse motion. Let us multiply it to 4.3 parsecs… we have 12.805
AU/yr. There are 1,915,628,000 km in 12.805 AU and 31,556,926 s in a tropical year, so the transverse velocity component is 60.7 km/s.
Incnis Mrsi (
talk) 18:59, 9 August 2012 (UTC)reply
Yes, the radial velocity determinations are all over the map. Of the papers I looked at, the
Aannestad et al (1993) seems to give the best accounting of the radial velocity with respect to the Sun. They list –38 km/s, the same value later assumed by Makarov (2004). So I'd say we should probably go with that. It's at odds with the value assumed by García-Sánchez et al (2001), so that should be yanked until a newer source becomes available. We may as well pull the space velocity information as well since Sion et al (2009) didn't clarify what value they used. Will that resolve the concern? Regards,
RJH (
talk) 01:07, 10 August 2012 (UTC)reply
That makes sense. The paper has a good discussion of the issue, and it might even be worth a few sentences in the article.
Praemonitus (
talk) 18:00, 11 March 2023 (UTC)reply
Mass
The article once claims that is mass is 68% of the Sun mass and 1.1% of the radius. Later, it claims that it is 63% of the Sun mass and 1% of the radius. Which mass is the correct one?— Preceding
unsigned comment added by
177.18.205.246 (
talk •
contribs) 2014-07-20T01:03:49
The distance table lists (consistently) a 13.3-14.4 ly distance), while the text claims 12.4 ly. Something is not right. — Preceding
unsigned comment added by
24.138.49.198 (
talk) 01:37, 21 May 2015 (UTC)reply
Found an astronomy web page to cite, but no confidence in it. Could be how the author thinks it should be pronounced rather than how ppl actually say it. Not just "van-MAN-inz"? Anyone know for sure? —
kwami (
talk) 07:37, 28 April 2019 (UTC)reply
Ref of 650 Rsol during the red giant phase
I wasn't able to find a ref for the 650 solar radii estimate during the red giant phase of Van Maanen 2, I did however find an estimate of 1,000 Rsol in the paper.
Nussun05 (
talk) 13:30, 1 August 2020 (UTC)reply
Thanks. It was originally 1,000, then was changed to 650 by
this edit. Possible OR?
Praemonitus (
talk) 02:23, 8 September 2020 (UTC)reply