NGC 4697 is an elliptical galaxy in Virgo.
William Herschel discovered this fine galaxy in 1784. Dreyer calls it very bright (mag 9.9), large (6'x3.8'), elongated, and containing a pronounced core. NGC 4697 is slightly flattened into a disk-like shape. Images also show a dark, wide band of dust encircling the center of the galaxy.
NGC 4697 lies some 40 million light-years away. Like other normal elliptical galaxies, NGC 4697 is a spherical ensemble of mainly older, fainter, low mass stars, with little star-forming gas and dust compared to spiral galaxies. But luminous sources in the X-ray images indicate that NGC 4697 had a wilder youth. Powering the X-ray sources are neutron stars and black holes in binary star systems, where X-rays are generated as matter from a more ordinary companion star falls in to these compact objects. Since neutron stars and black holes are the endpoints in the lives of massive stars, NGC 4697 must have had many bright, massive stars in its past.
An exceptionally large number of NGC 4697's X-ray binaries are found in the galaxy's globular star clusters, suggesting that dense star clusters are a good place for neutron stars and black holes to capture a companion. Stellar winds and supernova explosions of massive stars could also have produced the hot gas responsible for this galaxy's diffuse X-ray glow.
Astronomers have also likely discovered a supermassive black hole in the core of NGC 4697, as part of a survey with Hubble Space Telescope. By measuring the orbital motions of stars near the center of the galaxy, a team of astronomers concluded that the stars are orbiting a black hole of roughly 50 million to 100 million times the mass of the Sun.
This and other black holes in the hearts of galaxies suggest that there is a link between the black hole's mass and the overall mass of the galaxy. There is also evidence that the supermassive black holes may form first, and form as a sort of gravitational "seed" to attract the gas and dust that gives birth to a galaxy's stars.