What does 2736 mean?

NGC 2736, also known as the pencil nebula, is only a small part of the Vela supernova. (Vela is located in the southern hemisphere sky, 8 15 light years away from the earth. Astronomers believe that this supernova explosion occurred 1. 1 ten thousand years ago. The explosion ended the "life" of a huge star, leaving a pulsar-a fast-rotating neutron star in the supernova region. Although the disaster has passed for a long time, the waves formed by the explosion are still working today, spraying substances into the surrounding space. The colored stripes in the pencil nebula are the areas where the waves formed by the explosion collide with the interstellar gas dust cluster, which are generally invisible. However, in the process of supernova explosion, interstellar gas dust clusters will be heated and still emit radiation with different wavelengths. Light blue areas correspond to hotter gases, while light red areas correspond to colder gases. Unlike many other nebulae that only reflect the light from the central star, the pencil nebula emits light by itself due to the radiation of hot gas. Its shape is also unusual: usually the remaining nebula after supernova explosion has the shape of a sphere. But NGC 2736 is banded. If the calculation of the "age" of the supernova Vela is correct, the speed of the material ejected instantly after the supernova explosion will reach 35 million km/h, but now this speed has obviously slowed down: it is only 644,000 km/h in the pencil nebula. A bright star can also be seen in this photo, but it has nothing to do with the pencil nebula. Astronomers have not measured the distance between this bright star and the pencil nebula. )