Pleiades in 3-D!!!

March 2, 2007 12:04 AM

Astronomy-n00b question: Let's say I wanted to make a somewhat accurate 3D model of the major visible stars of the Pleiades cluster (say for, oh, i dunno.. an art project?). How would I go about acquiring the appropriate data?

I've gathered that there is a data set collected by the Hipparcos(?) sattelite which contains accurate data on the positions of 441 stars in said cluster, I've accessed it through the VisieR search page:
http://cdsweb.u-strasbg.fr/viz-bin/VizieR?-source=I/258
it seems to contain data points that might be relevant: right ascension and declination, I have yet to look those terms up but I imagine they tell me the stars position in the night sky. Good start, but then how would i determine the distance of each star from earth, the necessary third dimension? Also: how do I match up each star with it's common name (to separate out the major stars from the supporting cast) and is there a measurement of brightness? magnitude? mass?

help me hive mind!

posted by Gankmore to science & nature (6 answers total)

Yes, RA and DEC provide the position in the night sky.

There are plenty of catalogs which will provide the info you need. The HYG database is one. Here's a good guide to 3-d starmaps including links to the Yale bright star catalog.

Most of these catalogs, including Hipparcos provide parallax, not distance. parallax is the width in the sky of the star observed 6 months apart. To convert parallax to distance use:

distance (parsecs)=1/(parallax(arcsec))

Thats pretty much the definition of parsec.

If you want Mass, you can deduce it from the spectral type.
posted by vacapinta at 12:35 AM on March 2, 2007

Determining distance to far-away stars is pretty difficult. You can't just measure it, like you can a magnitude or position on the celestial sphere. Using parallax you can find distances to nearby stars and stitch your way out, at increasing error. For the Pleiades, the stars are close enough together that the error in distance to any star in the cluster is probably much larger than the relative distance between the stars in the cluster. In other words, there's not enough accuracy to make any kind of sensible 3-D model. There's more explanation at HubbleSite here, specifically about a modern measurement of the distance to the Pleiades.

The University of Hawaii's Institute for Astronomy (my employer) has a Pleiades sculpture you can see here. The wall is about 25 feet high. Each of the metal rods is maybe two feet in length, and represents a star in the cluster. The large stars have prisms at the end, and the desired effect is that when the sun is in the right place, prismatic rainbows are reflected all over the courtyard. Maybe this can give you some inspiration!
posted by ldenneau at 2:21 AM on March 2, 2007

Check out the 3D astronomy simulation program Celestia. They've already in incorporated a lot of data like this (I don't know about Pleiades specifically) and the entire thing is scriptable in Lua, so you might be able to output the data you want in a form that's easy to use without having to do a lot of hard conversion yourself.
posted by DU at 4:57 AM on March 2, 2007

This site may be helpful.
posted by jazzkat11 at 6:39 AM on March 2, 2007

Seconding celestia, which will not only tell you the distance to the stars, but will also tell you their radius relative to the sun (i.e. 2x radius of sun, etc). It also semi-accurately represents the color.
posted by Pastabagel at 7:15 AM on March 2, 2007

this is all so helpful, i'm tempted to mark every one of your answers as the best!
posted by garethspor at 11:27 AM on March 2, 2007