Astronomy Picture of the Day Project

Observatory / Course Archives / ASTR 110 Fall 2019 / Hurshman

TrEs - 2b

Explanation: The announcement of discovery of the extraordinary Exoplanet TrES - 2b was first published in October of 2016, but astronomers have known about it since 2006. TrES - 2b is 1.253 times the mass of Jupiter, which means it falls into the category of exoplanets called "hot jupiter". The characteristics of TrES - 2b that set it apart are its temperature (1444 K) and its albedo (0.015), or how much light an object reflects. The temperature is caused by the short distance (3 million miles) between it and it's star, but the reason for the incredibly low albedo is still unknown. Before TrES-2b was discovered, computer models predicted that hot jupiters could only ever get as dark as mercury, which has a much higher albedo, reflecting 10% of all the sunlight that hits it.

With only 0.015% of the light that hits it being reflected, it is known as one of the darkest objects in th universe. David Kipping, a researcher at the Harvard-Smithsonian Center for Astrophysics who studied TrES-2b described it like this: "TrES-2b is considerably less reflective than black acrylic paint, so it's truly an alien world". Study of this exoplanet has revealed that visually, it is not entirely dark. Rather, it emits a faint red glow due to its extreme temperature. The illustration above, which is creditied to David A. Aguilar, depicts an idea of what TrES-2b would look like.

Red Rectangle Nebula

Explanation: The aptly named Red Rectangle Nebula is a protoplanetary nebula located in the Monoceros constellation. A protoplanetary nebula is one of the final phases of stellar evolution for intermediate mass stars (between 0.8 and 8 solar masses). This stage occurs after the star travels along the Asymptotic Giant Branch and begins to shed its outer layers. The two stars that make up the binary system at the center of the RRN has been known about since 1915, but the RRN itself was not observed until 1973.

The RRN has been considered an anomaly for quite some time, as what we know about the laws of nature indicates that objects with high mass in space should be rounded, not rectangular. Over the nearly 50 years that we have known about the RRN, many theories have come out trying to explain the bizzare shape. One observation that seemed to explain the shape was that the star/binary system is surrounded by a dense cloud of dust, possibly forcing the nebula into a non-rounded shape. One of the most logical and well tested (by simulation) explanations said that the appearance of "ladder rungs" is a result of us seeing the nebula from the side. This explanation says that the nebula actually has a conical shape with concentric arcs throughout its stucture.

Q2237+030 (Einstein Cross)

Explanation: Pictured here is a quasar, or an extremely small, extremely bright object found in the center of a galaxy, orbiting around a supermassive black hole. The image of this specific quasar, known as the Einstein Cross, is located in the Pegasus constellation is a result of gravitational lensing. The object at the center of the formation is a galaxy around 400 million light years away. The four objects around the outside are actually the same object, a quasar around 8 billion light years away. The high mass of the galaxy bends spacetime and light bends with it, allowing us to recieve light from an object incredibly far away.

In 2015, a team of Spanish astrophysicists was able to obtain measurements that are incredibly accurate for the distance of the quasar. Jorge Jimenez Vicente, one of the members of the team, said that the detection of a quasar so far away with such detail was like, "...being able to detect a one euro coin located over 100,000 kilometers away." Another thing that makes this discovery so remarkable is the fact that although the quasar's light passes through the spiral galaxy between us and it, the light suffers from very little reddening from dust.