What is the diameter of star clusters?

In summary, the conversation discusses the process of determining the diameter of a star cluster using its RA and Dec coordinates. It is suggested to use the cluster's magnitude and distance to calculate its angular size, or to search for the angular size in a catalogue. The equation for finding the diameter is based on trigonometry and the assumption of the cluster being spherical. It is also recommended to research the process of determining the diameter of the moon for a better understanding.
  • #1
randa177
91
1
Maybe this is stupid question, but I am not sure how to get the diameter of the star cluster, I assume from the RA and Dec. I googled it and tried to come with a realtion between the RA , Dec and Diameter from Andrea's proposal but couldn't figure the correct answer
This is all I find (see below please)... but I don't know the distance or the angular size, just RA and Dec from SIMBAD data base
diameter = 2p × (distance to the cluste) × (clsuter's angular size in degrees)/360°
 
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  • #2
randa177 said:
Maybe this is stupid question, but I am not sure how to get the diameter of the star cluster, I assume from the RA and Dec. I googled it and tried to come with a realtion between the RA , Dec and Diameter from Andrea's proposal but couldn't figure the correct answer
This is all I find (see below please)... but I don't know the distance or the angular size, just RA and Dec from SIMBAD data base
diameter = 2p × (distance to the cluste) × (clsuter's angular size in degrees)/360°

hey, i can't quite remember everything, but here goes:

if u have the magnitude of the cluster u can work out the distance to the cluster. the absoulte magnitude of the cluster will (should) be on simbad.

the equation for magnitude and distance is:
http://ceres.hsc.edu/homepages/classes/astronomy/spring99/Mathematics/sec19.html

u can work out the angular size using the distance u just calculated using:
http://galacticfool.com/what-is-angular-size/

however, it should be poss to find out the cluster's angular size from a catalogue.
If simdbad doesn't have it, use the search tool to search thro all the other cataloguesthat simbad has access too:
http://vizier.u-strasbg.fr/viz-bin/VizieR

enter the cluster's name or ra and dec and it will give u a list of catalogues which has data on which u can view by selecting them. it will take some time but u prob will be able to find the clusters angular size :) (no gauntees of course!) if u do have enough info to use the formula i would recommend doing it the formula way lol for time purposes

the eqaution u wrote is based on triganometry, and assuming the cluster is spherical (just like working out the disameter of the moon, but further away) so i would recommend looking up about working out the diamter of the moon, they have good diagrams to help u visualise the problem and understand it better

hope this helps

p.s apologys for the poor spelling!
 
Last edited by a moderator:

1. What is the diameter of a star cluster?

The diameter of a star cluster can vary greatly, ranging from a few light years to over 100 light years. The size depends on the number of stars in the cluster and their distribution within it.

2. How is the diameter of a star cluster measured?

The diameter of a star cluster is typically measured in light years, which is the distance that light travels in one year. This measurement is based on the distance between the furthest stars in the cluster.

3. Can the diameter of a star cluster change over time?

Yes, the diameter of a star cluster can change over time due to various factors such as interactions with other clusters, gravitational forces, and the formation or destruction of stars within the cluster.

4. Are all star clusters the same size?

No, star clusters can vary greatly in size depending on their age, composition, and location within the galaxy. Globular clusters, which are older and have a more compact shape, tend to be smaller in diameter compared to open clusters.

5. How does the diameter of a star cluster affect its lifespan?

The diameter of a star cluster does not necessarily affect its lifespan. However, larger clusters tend to have a higher rate of star formation and therefore may have a longer lifespan. Smaller clusters may disperse more quickly due to interactions with other objects in space.

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