Stellar Objects

Observatory / Course Archives / ASTR 110 Fall 2019 / Cordeiro

Venus

Venus, being the second planet in the Solar System is about 0.7 astronomical units (AU) from the sun or 108 million km. It was first discovered in the ancient times; in Babylon, the planet was called Ishtar about 5000 years ago. The Persians have recorded the transit of Venus in 1032 AD. Venus is Earth’s twin for similar size, mass, and location. Venus has an almost perfect circle and has a slight tilt of 3 degrees. One full orbit is equal to 225 Earth days while one day is equivalent to 243 Earth days. Not only that, Venus orbits clockwise unlike the other planets of the solar system.

Venus has a very thick atmosphere. Most of the atmosphere (96%) is Carbon Dioxide (CO2). This thick atmosphere traps the heat inside of the planet causing it to have a surface temperature of 737 degrees Kelvin (464 Celsius). The picture of Venus above, taken in the UV spectrum, shows the thick atmosphere contained inside of Venus. Using UV radiation, the atmosphere becomes visible since using visible light would probably be overexposed since the clouds make the planet highly reflective making it the second brightest object in the night sky after the moon. The surface is covered in plains mostly (about 2/3). The remaining third of the surface is filled with active volcanoes causing the surface to change constantly.

Butterfly Nebula

The Butterfly Nebula (NGC 6302), first discovered in 1888, is in the Scorpius Constellation. The nebula is visible in the Northern Hemisphere around July and August near the horizon. The dying star, located in the center of the nebula, is burning at 250,00 degrees Celsius while it is blasting hot gas (which is over 18,000 degrees Celsius) at over 900,000 km per hour. The explosion has grown to 2.7 light years across with a brightness of 9.6 magnitude at four kilo light years from us.

Edward Emerson Barnard was the first one to conduct research of the Butterfly Nebula in 1907. It was classified as a planetary nebula. A planetary nebula is gas and dust resulting from a collapsed star. The dust is made up of Oxygen, Helium, Hydrogen, Nitrogen, and Sulfur. The term was first created by William Herschel when he realized he was looking at gas and dust which shared colors with Uranus and not a cluster of stars.

Pearl Cluster

Located in the Centaurus Constellation, the Pearl Cluster (NGC 3766) is best visible in the Southern Hemisphere, about 1.5 degrees north of Lambda Centauri. It is 7.2 kilo light years from us and as a brightness of 5.6 magnitude.

The Pearl Cluster is an open cluster, meaning that it has several hundred relatively young stars grouped together. Young stars would be colored in blue or white, as it is seen in the picture above. These young stars are hotter than red or yellow stars, but they also do not live for that long. The cluster also has 36 known variable stars with periods ranging from two to twenty hours. Variable stars are stars that can change its brightness from a thousandth of a magnitude to over 20 magnitudes.