Hubble reveals warped disk around black hole

An immense warped dust disk surrounding a suspected black hole has been discovered by astronomers Philippe Crane and Jöel Vernet of the European Southern Observatory, Garching, Germany, facility. Pointing the orbiting Hubble Space Telescope toward the galaxy NGC 6251, an elliptical galaxy located 370 million light years away in the constellation Ursa Minor (the Little Dipper), Crane and Vernet used the Hubble`s Faint Object Camera (FOC) to obtain an ultraviolet (UV) image of the galaxy at 340 nm.

Superposition of this image on an archived image in the visual range revealed that the UV light produced by the hot gas trapped by a black hole`s gravitational field radiates outward in two "jets" from the galaxy`s nucleus. The southern emission extends about 910 light years and fills the inner regions of the 1000 light-years-wide dust ring. Its north-south asymmetry suggests that the dust disk is apparently not planar but warped, like the brim of a hat, obscuring the emission to the north more effectively. The observation represents the first clear example of an exposed black hole, observed from above the toric dust ring, and of a bowed dust disk.

The capabilities of the Hubble`s FOC were restored by the 1993 shuttle mission that installed the Corrective Optics Space Telescope Axial Replacement (COSTAR). The FOC, built by the European Space Agency, is now a diffraction-limited camera with superb image quality and the highest spatial resolution ever achieved in the 115-650-nm wavelength range. The camera allows deep imagery and photometry of very faint celestial objects with resolution down to 50 light years.

The researchers will use ground-based facilities to follow up their conclusions, said Crane, such as the Very Large Array (VLA) radio telescope near Socorro, NM, and the Canada-France-Hawaii Telescope in Mauna Kea, HI, and will propose using the Hubble to look at other extragalactic jet sources that have dust.