<p>Do you know this paper? <a href="http://arxiv.org/abs/astro-ph/0507416" rel="nofollow">Mamajek (2005). "A Moving Cluster Distance to the Exoplanet 2M1207b in the TW Hydrae Association"</a>.</p>

<p>I'll risk an opinion:
There is about a thousand clusters with kinematic measurements, but besides no more than half a dozen, all pm components are under 20 mas (milli-arcseconds) with errors more or less in the range 0.3-6 mas. Such errors are too high in relation to the pm values and as a result, the vectors will not converge.</p>

CC BY-SA 3.0
2014-02-05T17:24:40.403Z
2014-02-05T17:24:40.403Z
Bruno Alessi
<p>At all places where I have read of Moving Cluster Method for measuring distance to a cluster and once applied myself on data, I have been told that the method has been successfully applied only to Hyades cluster in Taurus.</p>

<p><img src="https://i.sstatic.net/rb1LP.png" alt="hyades cluster moving cluster method"></p>

<p><strong>Question :</strong> What factor made the method unsuccessful for other known clusters? </p>

CC BY-SA 3.0
2014-02-02T14:32:36.690Z
I'd suggest it is because, for the method to work, the cluster needs to be nearby and, in effect, relatively young (as open clusters get broken up otherwise) - eg the Hyades are about half the distance to the Pleiades and an order of magnitude younger than the Solar System. An additional factor is that the Hyades are a well-known yardstick for astronomical distances and so measuring them first would be a scientific priority.
adrianmcmenamin
CC BY-SA 3.0
2013-10-27T20:52:25.700Z
would you mind explain how the method works (mayby adding some link)?
Francesco Montesano
<distances>
Why has Moving Cluster Method been successful only for Hyades?
Cheeku
# Why has Moving Cluster Method been successful only for Hyades?

(Asked by: username_0 on 2013-09-28)

At all places where I have read of Moving Cluster Method for measuring distance to a cluster and once applied myself on data, I have been told that the method has been successfully applied only to Hyades cluster in Taurus.

![hyades cluster moving cluster method](https://i.sstatic.net/rb1LP.png)

**Question :** What factor made the method unsuccessful for other known clusters?

**Tags:** distances
> **Comments:**
> **username_2**: would you mind explain how the method works (mayby adding some link)?  
> **username_1**: I'd suggest it is because, for the method to work, the cluster needs to be nearby and, in effect, relatively young (as open clusters get broken up otherwise) - eg the Hyades are about half the distance to the Pleiades and an order of magnitude younger than the Solar System. An additional factor is that the Hyades are a well-known yardstick for astronomical distances and so measuring them first would be a scientific priority.  

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## 1 answers

### Answer by username_3 on 2014-02-05. Score: 3

Do you know this paper? [Mamajek (2005). "A Moving Cluster Distance to the Exoplanet 2M1207b in the TW Hydrae Association"](http://arxiv.org/abs/astro-ph/0507416).

I'll risk an opinion:
There is about a thousand clusters with kinematic measurements, but besides no more than half a dozen, all pm components are under 20 mas (milli-arcseconds) with errors more or less in the range 0.3-6 mas. Such errors are too high in relation to the pm values and as a result, the vectors will not converge.


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