Does Interstellar Extinction Change the Angular Size of Star Clusters?

[randa177]

The presence of interstellar extinction makes stars appear dimmer and appear more “distant” than they truly are. (This is true for individual stars and for clusters of stars). Does dust affect the observed angular size of a star cluster (assuming the distribution of the dust is smooth)? That is, suppose there was a star cluster located 100 pc away. Would adding dust extinction affect its observed angular size?

 

[mgb_phys]

No the dust just reduces the apparent brightness, and changes the obserserved colour.

 

[tacman]

Yes, the presence of interstellar extinction can affect the observed angular size of a star cluster. This is because dust particles in the interstellar medium can scatter and absorb light, making stars appear dimmer and more distant than they actually are. This is true for individual stars as well as for clusters of stars.

In the case of a star cluster located 100 pc away, adding dust extinction would affect its observed angular size. This is because the dust particles would scatter and absorb some of the light coming from the stars in the cluster, making them appear dimmer and more spread out. This would result in a decrease in the apparent angular size of the cluster as seen from Earth.

However, it is important to note that the effect of dust on the observed angular size of a star cluster would depend on the distribution of the dust. If the dust is evenly distributed, the effect would be more uniform and the angular size of the cluster would decrease in a relatively consistent manner. However, if the dust is clumped in certain areas, the effect on the observed angular size may be more variable and may even result in some parts of the cluster appearing larger or smaller than others.

In conclusion, interstellar extinction caused by dust can indeed affect the observed angular size of a star cluster. This is an important consideration when studying and interpreting observations of star clusters, as the presence of dust can impact our understanding of their physical properties and distances.