How far away is spiral galaxy NGC
4921? Although presently estimated to be about 310 million light years distant,
a more precise determination could be coupled with its known recession speed to
help humanity better calibrate the expansion rate of the entire visible
universe. Toward this goal, several images were taken by the Hubble Space
Telescope in order to help identify key stellar distance markers known as
Cepheid variable stars. Since NGC 4921 is a member of the Coma Cluster of
Galaxies, refining its distance would also allow a better distance
determination to one of the largest nearby clusters in the local universe. The
magnificent spiral NGC 4921 has been informally dubbed anemic because of its
low rate of star formation and low surface brightness. Visible in the above
image are, from the center, a bright nucleus, a bright central bar, a prominent
ring of dark dust, blue clusters of recently formed stars, several smaller
companion galaxies, unrelated galaxies in the far distant universe, and unrelated
stars in our Milky Way Galaxy.
هیچ نظری موجود نیست:
ارسال یک نظر