Posts Tagged ‘Large Magellanic Cloud’

1122/2016 – Cepheus the king and its one really important star

November 22, 2016 Comments off

Ephemeris for Tuesday, November 22nd.  The Sun will rise at 7:49.  It’ll be up for 9 hours and 18 minutes, setting at 5:08.  The Moon, 1 day past last quarter, will rise at 1:56 tomorrow morning.  |  There’s a faint constellation in the north above Polaris.  It’s a nearly upside down church steeple of a constellation called Cepheus the king, and husband of queen Cassiopeia the W shaped constellation right of it.  Cepheus’ claim to astronomical fame is that one of its stars, Delta (δ) Cephei, is the archetype for the important Cepheid variable stars.  Delta is in a trio of stars at the top corner of the constellation, and the one on the right.  In the early 20th century Henrietta Leavitt discovered that Cepheids in the nearby galaxy the Large Magellanic Cloud varied in brightness with a period that was related to their average brightness.  This meant that Cepheids could be used as standard candles to measure great distances to other galaxies.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.



Cepheus animated finder chart for 8 p.m. November 22, 2016. Created using Stellarium and GIMP.

Delta Cephei finder chart

Delta Cephei finder chart. This is the same orientation as the chart above, but created using Cartes du Ciel (Sky Charts). A green line points to Delta (δ) Cephei.

A word about star designations in the chart above.  In general only the brightest stars have proper names.  And those usually come from antiquity, and most of those are Arabic.  Star designations which are Greek lower case letters come from Johann Bayer’s Uranometria star atlas from 1603.  He designated the stars by order of brightness.  In constellations with a lot of stars he moved to the Latin alphabet after running out of Greek letters.  These were, of course, naked eye stars; the atlas being produced a few years before the invention of the telescope.  Stars with numbers are Flamsteed designations from John Flamsteed’s 1725 star catalog.  He numbered his stars from west to east in a particular constellation, but only those stars that could be seen from Great Britain.  A single star can have many catalog designations.  For instance the bright star Vega in Lyra the harp is Alpha (α) Lyrae, Bayer designation; 3 Lyrae, Flamsteed designation; HD 172167, Henry Draper catalog; BD +38 3238,  Bonner Durchmusterung, a German catalog; HIP 91262, Hipparcos catalog, and so on.