TAAS Monthly Observing Challenge – July 2016

Deep Sky Object

NGC 7296 (OC) Lacerta ra: 22h 28m 01.0s dec: +52° 18’ 48” Magnitude (visual) = 9.7 Size = 3.0’ Distance = approximately 6.800 +/- 310 light

Description: NGC 7296 is a small, compact cluster of 10th and 11th magnitude in Lacerta that is almost lost in the rich background of Milky Way stars.

Source: http://www.phys.ttu.edu/~ozprof/7296c.htm

See https://www.researchgate.net/publication/230527007_A_morphological_analysis_of_NGC_7296 for a fascinating paper on this object.

AL: Herschel 400

Challenge Object

NGC 6729 (BN) ra: 19h 01m 54.0s dec: -36° 57’ 00.0” Magnitude (visual) = undetermined Size = 1’ x 1’ Distance = approximately 425 light years

Description: NGC 6729 is a reflection/emission in the Corona Australis. It was discovered by Johann Friedrich Julius Schmidt in 1861.

This fan-shaped nebula opens from the toward the star T CrA to the south-east. R CrA is a pre- main-sequence star in the Corona Australis molecular complex, one of the closer star-forming regions of the at a distance of 130 .

Source: http://en.wikipedia.org/wiki/NGC_6729

AL: Caldwell 68

Photograph used with permission of Capella Observatory

Binocular Object

M107 / NGC 6171 (GC) Ophiuchus ra: 16h 32m 31.9s dec: -13° 03’ 13.0” Magnitude (visual) = 7.8 Size = 13’ Concentration Class = 10 Distance = approximately 21,000 light years

Description: Messier 107 (M107, NGC 6171) is another additional object found by Pierre Méchain in April, 1782. Herewith, it is probably the which was the latest to be discovered. Eventually, Helen Sawyer Hogg added it to the Messier Catalog in 1947, together with M105 and M106, although it appears probable that already Méchain had intended to add it to a future edition of Charles Messier's list. William Herschel, who had independently discovered it on May 12, 1793,cataloged this object as H VI.40; Herschel was the first observer to resolve this globular cluster into stars. M107 apparently contains some dark obscured regions, which is unusual for globular clusters. The star distribution is called "very open" by Kenneth Glyn Jones, who points out that this cluster "enables the interstellar regions to be examined more easily, and globular clusters are important `laboratories' in which to study the process by which evolve." Visually, M107 is about 3 minutes of arc across, while in photos it extends over a region more than 4 times this diameter (about 13'). As its distance is about 21,000 light years, this corresponds to roughly 80 light years. M107 is approaching us at 147 km/sec, contains about 25 known variables, and as a globular cluster, is of intermediate metallicity (abundances of elements heavier than Helium).

Source: http://messier.seds.org/m/m107.html

AL: Binocular Messier

Double Star

Beta Capricorni (DS) Capricorn – aka Dahib ra: 20h 21m 00.7s dec: -14° 46’53” Magnitudes (visual) = 3.2,6.1 Separation = 207” Position angle = 267° Distance = approximately 328 light years

Description: Dabih, the Beta star of , the "water goat," is among the more complex of the sky's naked-eye stars. Second brightest in the constellation (after Deneb Algedi, the Delta star), it shines to us at mid-third (3.08) magnitude. Its name, from ancient Arabic lore that has nothing to do with the classic Greek constellation, refers to both Dabih and Algedi (Alpha Capricorni) as the "lucky stars" of a mysterious slaughterer, the true meaning quite lost to history. The star is a bit of a mess, or at least such is our knowledge of it. First, it is a wide naked-eye (or at least binocular) double. The pair, separated by over three minutes of arc (205 seconds), is dominated by third magnitude "Dabih Major," the sixth magnitude (6.10) companion referred to as "Dabih Minor" (or sometimes Beta Minor, or Beta-1, rendering Dabih Major Beta-2).

At a distance of 330 light years, the two are separated by at least 21,000 astronomical units and take at least a million years to make a circuit around each other. Dabih Minor, the simpler of the two, is dominated by a class B (B9.5) giant or subgiant (meaning it is evolved and has stopped, or nearly stopped, fusing hydrogen in its core) that shines about 40 times brighter than our . However, lunar (in which the covers the star) as well as space- based observations show it is not one star but two, the other much fainter and probably a cooler class F ordinary dwarf separated from its host by about 30 astronomical units (AU, the distance between Earth and Sun). No has been determined.

Source: http://stars/astro.illinois.edu/sow/dahib.html

AL: