Sunflower Galaxy (M 63)

The Sunflower Galaxy (M63) is a spiral galaxy located in the constellation Canes Venatici, about 37 million light-years from the Sun. With a diameter of about 100,000 light-years, it is similar in size to the Milky Way. However, the mass of the galaxy M63 is 140 billion times greater than our own. Its structure is characterized by a central bright yellow disk, from which spiral arms diverge, reminiscent of the shape of a sunflower.

The stars on the outskirts of the galaxy rotate so quickly that they should leave it, but this does not happen. This phenomenon has become one of the proofs of the existence of dark matter, which holds matter in galaxies. In 2011, a tidal stream of stars was noticed in the halo, which formed after accretion over the past 5 billion years. Although the second participant in this process is unknown, an analysis of the colors of the stars allows us to assert that they belonged to the Local Group.

Discovery and Exploration

The galaxy was discovered by the French astronomer Pierre Méchain in 1779, and later confirmed by his colleague Charles Messier. In the 19th century, the Anglo-Irish astronomer Lord Rosse identified spiral structures within the galaxy, making it one of the first galaxies to be found to have such a structure.

Structure and Characteristics

M63 is classified as a bar-less (SAbc) spiral galaxy, with moderately curled spiral arms. In visible light, it lacks large-scale spiral structure, so it is considered a flocculent galaxy. However, near-infrared observations reveal a symmetrical structure with two spiral arms that wrap around the galaxy by 150° and extend 13,000 light years from its center.

Activity and Black Hole

M63 is a weakly active galaxy with a LINER (Low-Ionization Nuclear Emission-Line Region) core, which is an unresolved source at the center of the galaxy covered in diffuse radiation. Notably, this radiation contains soft X-rays and hydrogen (H-alpha) emission, suggesting the possible existence of a supermassive black hole with a mass of about 850 million solar masses, although this has not been proven.

Radio Observations and Dark Matter

Radio observations at the 21-cm hydrogen line show that the gas disk of M63 extends to a radius of 130,000 light-years, well beyond the bright optical disk. The gas structure is symmetrical, but noticeably warped starting at a radius of 33,000 light-years, suggesting the presence of dark matter that is offset from the central region.

History of observations

M63 was first noticed in 1779 by the French astronomer Pierre Méchain and was one of 24 objects that Méchain added to the Messier catalog. In 1850, Lord Rosset included it in a list of 14 "spiral nebulae".

Supernovae

M63 has hosted one supernova: SN 1971I (Type Ia, magnitude 11.8), discovered on May 24, 1971 by Glenn Jolly and later independently discovered by Roger Clark.

Conclusion

The Sunflower Galaxy is one of the brightest and most studied spiral galaxies, with unique structures and features that continue to attract the attention of astronomers and scientists.