Pavo
Written by Tammy Plotner
Located south of the ecliptic plane, the constellation of Pavo was created by Petrus Plancius from the observations of Dutch navigators, Pieter Dirkszoon Keyser and Frederick de Houtman. It first appeared on Plancius celestial globe in the late 1500s and was included in Johann Bayer's Uranometria of 1603. It was later adopted as one of the 88 modern constellations by the International Astronomical Union in 1930. Pavo covers 378 square degrees of sky and ranks 44th in size. It has 7 main stars in its asterism and contains 24 stars with Bayer Flamsteed designations within its confines. Pavo is bordered by the constellations of Octans, Apus. Ara. Telescopium and Indus. It is visible to observers located at latitudes between +30° and ?90° and is best seen at culmination during the month of August.
There is one annual meteor shower associated with Pavo which peaks on or about April 4, but the activity for this variable meteor shower can begin as early as March 29 and end as late as April 8. The hourly activity rate averages about 5-7 meteors per hour and the parent comet would appear to be comet Grigg-Mellish, but it has not yet been confirmed.
Since Pavo is considered a "new" constellation, there is no mythology associated with it. The term "Pavo" in Latin denotes the "peacock" and the constellation is often depicted as this highly colorful bird and associated with Indus the Indian. The Dutch explorers would have encountered a new species of peacock during their travels, and perhaps this is what prompted them to so name the constellation.
We begin our binocular tour of Pavo with a look at its brightest star – Alpha – the "a" symbol on our map. Named Peacock, this blue subgiant star is also a spectroscopic binary star and is located about 187 light years from Earth. Only a fraction larger than our Sun, Peacock burns blue because it's much hotter. How hot? Try a has surface temperature of 11000 to 28000 Kelvin. It's a nice color contrast to nearby, cooler Beta Indi!
Now, take a look at Beta – the "B" symbol on our map. It's a massive A-type star. Hop west for Delta, the "8" symbol. Delta is just barely 20 light years away from our own solar system and it's very interested because it is almost identical to our own Sun. So identical, in fact, that Delta has become one of the top 100 target stars for NASA's planned Terrestrial Planet Finder (TPF)!
In the mood for a visual double star? The drop south towards the celestial pole for Upsilon 1 and 2 – the "u" symbol on our map. While the two Upsilons aren't physically related to each other, they make a pleasing pair in binoculars and to acute vision!
Keep your binoculars or small telescopes on hand for globular cluster NGC 6752 (RA 19:10:51.8 Dec -59:58:55). At about magnitude 5.5, this sturdy little globular cluster was discovered by James Dunlop on July 28, 1826, but may have been noted by Abbe Lacaille in 1751-52. Look for a well condensed core region in this highly evolved galactic gem!
For a more challenging telescope object, try spiral galaxy NGC 6744 (RA 19:09:46.1 Dec -63:51:27). Located about 25 million light years away from our own Milky Way Galaxy, this spiral has a lot in common with our own – including spiral galaxy structure – and at least one distorted companion galaxy which is vaguely similar to one of the Magellanic Clouds.
Try your hand a barred spiral galaxy, NGC 6684 (RA 18:49.0 Dec -65:11), too. At one time, Helen Sawyer Hogg has this object listed as a globular cluster! At magnitude 10.5, it's a good target for mid-sized telescopes, and a prized study for velocity and velocity dispersion and stellar kinematics as well.
For large telescopes, try NGC 6753 (RA 19:11.4 Dec -57:03). At magnitude 12 and about 2 arc minutes in size, this face-on spiral galaxy not going to be the easiest you've ever tried, but it was home to a bright supernova event in 2000!
Chart courtesy of Your Sky.
Filed under: Astronomy
