History tells us that March comes in like a lion and goes out like a lamb. Maybe that was before global warming: March has already come in like a lamb, with plenty of mild and clear nights, at least here in central Texas. And while that may not last forever, it’s a perfect opportunity to get out and poke around in the spring skies. As usual, a few morsels are below. But whatever you like to chew on, do get out and enjoy!

21 LMi rating EASY
   star in Leo Minor
   RA 10h 07.4m  Dec +35d 14.7′  (2000)
   Magnitude 4.5

Which star cluster is so close that you can’t see it in binoculars? How about Collinder 265, also known as the Ursa Major Moving Cluster? Centered about 75 light-years away, the UMa Moving Cluster is closer than any other known star cluster.

21 LMi is an outlying member of this cluster, which was was first identified in 1869 by Richard Proctor. He determined that the 5 bright central stars of the Big Dipper (in Ursa Major) were moving in the same direction through space at the same speed, a conclusion confirmed 3 years
later by William Huggins.

The elongated core of the cluster, at least 10×20 light-years in size, translates into an apparent diameter greater than 20 degrees across the sky. As a result, although the UMa Moving cluster is centered on the Big Dipper, it also includes stars from Corona Borealis to Leo and Leo Minor, including 21 LMi.

R UMa  rating MEDIUM
   variable star in Ursa Major
   RA 10h 44.7m  Dec +68d 46.3′  (2000)
   Magnitude 7-13

R UMa is a pulsating red giant star of the Mira class, closely comparable to Mira in period, range and spectral type. Located in northern Ursa Major about 4 degrees east of galaxy M81, it was the first long-period variable star found in Ursa Major, by Pogson in 1853.

Although it occasionally reaches 6.7 or so at high maximum, R has a usual range of 7.5 to about 13 in a cycle averaging 302 days. When near the bottom of its cycle, R is one of the reddest of the long-period variables; however, the intense color weakens as the star rises to maximum. And as it brightens it does so about twice as fast as it fades, with a min to max time of about 116 days. If you’re interested in following this curve, note that the last maximum of R was 12 November 2015.

R has a peak luminosity of about 250 times that of the Sun. However, it is about 6 times more remote than Mira, with an estimated distance of around 1350 light-years. And it’s also receding from us at about 20 miles per second, so don’t wait too long to take a look!

Leo I   rating HARD
  Local Group dwarf galaxy, near Regulus
  RA 10h 8.4m  Dec +12d 18.0′  (2000)
  Magnitude 9.8,  diameter 10′ (1000 LY),  distance 250 kpc (800000 LY)

Leo I is a dwarf spheroidal (Hubble type E3) member of our Local Group of galaxies. Lying over half a million light-years away, it’s one of the most distant of 11 Local Group dwarf galaxies. Most of the smaller Local Group members resemble this object. Star formation in Leo I ended about 10 billion years ago, compared to more than 15 billion years ago for a typical globular cluster like M13.

Visually, Leo I is a swarm of stars magnitude 20 and fainter. Although it has a total magnitude near 10th, its low surface brightness (due to its 10′ disk) and its proximity to Regulus (which is 15″ south) make it a difficult object. It can be observed with a 17-inch telescope if Regulus is kept out of the field.

If you don’t have a 17-inch scope handy, a nice APOD image by David Malin
can be found at:  http://antwrp.gsfc.nasa.gov/apod/ap991003.html