NGC 2392, the Eskimo Nebula by HST. Image credit: NASA/ESA

NGC 2392, known as the Eskimo Nebula or Clown Nebula, a spectacular planetary nebula that was discovered in 1787 by William Herschel. The nebula spans one-third light-year and is found in our galaxy, In the constellation Geminis, about 5000 light years from Earth.

NGC 2392 is a planetary nebula (it is called a planetary nebula to bubbles of gases ejected by dying solar-type stars). What we see is a star in the process of becoming white dwarf, a process that began about 10,000 years ago, when the star became a red giant due to the depletion of its hydrogen reserves. Lacking enough energy, the star cooled, expanding its outer layers and forming a sphere around it. Some studies defend the presence of a disk of material around the star, so that when it expanded the denser material also did, becoming these cometary-looking filaments. Then the star began to collapse, causing strong winds of 115,000 km / h and the emission of two gaseous lobes that came out.

Eskimo Nebula in 32 inch telescope. Image source: (1)

Messier 1

The Crab Nebula - five observatories (animation; 10 May 2017). Image source: (2)

The Crab Nebula is made up of the remains of one of the most spectacular and known supernovae. It is located 6,500 light-years away, in the constellation Taurus, and is about 11 light-years in diameter. It has a look that resembles that of an eye, and its shape makes one think of an explosion of cosmic dimensions. The frayed filaments of matter forming their "body" are at temperatures of 15,000 degrees Celsius, while the surface of the Sun is only "5,000 degrees Celsius, and, in short, the nebula produces 75,000 times more energy than our star.

 
In the center of the huge nebula, which grows at a dizzying pace of 1,000 million kilometers per day. It is found the corpse of the star that exploded and originated the supernova. It is a neutron star, in which matter is strongly compacted. It emits an intense magnetic field and powerful pulses of electromagnetic radiation of periodic form, reason why it is said that it is a pulsar. Although it weighs 1.5 times more than the Sun, its diameter is only 30 kilometers (compared to almost 1,400 million kilometers of the Sun). In addition, the small star turns on itself once every 33 milliseconds.

The nebula is seen in the visible spectrum at 550 nm (green light). Image source: (3)

Image combining optical data from Hubble (in red) and X-ray images from Chandra X-ray Observatory (in blue). Image source: (4)