• IPAC

Arp 102B/Chary


Using Spitzer Space Telescope infrared spectra to detect the structure around the supermassive black hole at the center of the active galaxy Arp 102B.


Arp102B is a radio-loud, Seyfert 1 galaxy located in the constellation Hercules with a B-band magnitude of 15.2 mag. It has a redshift z = 0.024, giving it a recessional velocity of 7250 km/s and a distance of about 99.1Mpc. At its core is a low luminosity AGN with a black hole estimated to be ~108 solar masses. Although there have be en many radio, X-ray, UV, optical, and ground-based IR studies of the Arp102B nucleus , they have not converged to produce a single, unified model for the nucleus.

For example, Chen and Halpern (1989) used a geometrically thin, optically thick accretion disk model to fit double-peaked Balmer lines in the spectrum of Arp102B. Sulentic (1998) suggested that a bicone model would better fit the Fe K alpha lines in the x-ray spectrum. Korista summarizes the current state of our understanding as follows: "Despite significant progress, some fundamental issues relating to the geometry of the broad line emitting gas remain unsolved. We do not know whether in general the broad line region is composed of discrete clouds, winds, disks, or bloated stellar atmospheres or a combination of these." (Strateva et al., 2003)

We believe that quality spectral data covering the IR spectrum may be the key to resolving these differences and could lead to a unified model for this type of AGN. Therefore, we propose to use Spitzer's IRS instrument to obtain LH, SH, SL1 and SL2 spectral data of Arp102's supermassive blackhole. With this data, we can measure the mass of the black hole, analyze the geometry, composition, and physical properties of the dust structure surrounding the black hole and reach conclusions about the energy production mechanism(s) in the nucleus.

Mentor Astronomer


Mentor Educator


Mr. Harlan Devore

Cape Fear High School, Fayetteville, North Carolina

Participant Educator


Mr. Lauren Chapple

Traverse City East Junior High School, Traverse City, Michigan

Participant Educator




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