Star Distances

by John Church

At last November’s business meeting it was mentioned that on public nights at the observatory, team members are often asked how far away a particular star is. To help us answer these questions, I’ve generated a list for some of the better-known stars.  I’ve also added data for visual magnitudes, absolute magnitudes (i.e. how bright each star would appear if it were at the standard distance of 10 parsecs or 32.6 light-years), and its approximate brightness relative to our puny little Sun.  In the case of multiple stars, which many of these are, the values are for the primary.

If the Sun were at this standard distance, at magnitude + 4.8 it would be barely visible to the naked eye in a moonless central NJ clear night sky.  But note Deneb, which has an absolute magnitude of  – 8.4.  If it were at this distance it would be 4 magnitudes brighter than Venus at its best – about like a 5-day-old Moon – greatly interfering with our modest view of the summer Milky Way and easily visible by day. Rigel, if similarly placed, would not be far behind in the winter sky.  Monster stars like this have been called “galactic beacons.”

More comparisons:  If the Sun were at the actual distance of brilliant Sirius, it would be of 2nd magnitude, i.e about the same as Castor or Polaris.  And, at the distance of Deneb, it would only be of magnitude 14.4, about as dim as Pluto appears from Earth.  Shrimp though the Sun is in the grand scheme, it’s still our favorite star.
Screen Shot 2016-04-02 at 10.31.39 AM

Perhaps this table could be posted on the observatory wall for convenient access.

Congratulations John for submitting the 500th article to Sidereal Times!

This entry was posted in April 2016, Sidereal Times and tagged , , . Bookmark the permalink.

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