Messier 87 - the Virgo A Supergiant Galaxy

Description:

"A subset of 150 globular clusters (GCs) in M87 has been selected for abundance and age determinations from the 1997 sample of Cohen & Ryzhov. This has been done solely on the basis of the signal-to-noise ratios of the spectra. Indices that measure the strength of the strongest spectral features were determined for the M87 GCs and from new data for twelve galactic GCs. Combining the new and existing data for the galactic GCs and comparing the (U-R) colors and the line indices gave qualitative indications for the ages and abundances of the M87 GC system. Quantitative results, which confirm and extend the qualitative ones, were obtained by applying the Worthey models for the integrated light of stellar systems of a single age, calibrated by observations of galactic globular clusters, to deduce abundances and ages for the objects in our sample."

"The giant radio galaxy M87, well studied from radio to X-ray energies, is located in the Virgo cluster of galaxies at a distance of 16 Mpc (redshift z=0.00436). M87 has been observed with the HEGRA stereoscopic system of five Cherenkov telescopes in the years 1998 and 1999 for more than 80 h. An excess of TeV ?-rays on the 4? level has been found in the data corresponding to an integral flux (E>730 GeV) of 3.3% of the Crab nebula flux. The HEGRA detection – if confirmed – would make M87 the first TeV ?-ray emitting AGN observed with the imaging atmospheric Cherenkov technique not belonging to the BL Lac class."

"A knot along the M87 jet located 085 from the nucleus of the galaxy, has experienced dramatic and unexpected flaring activity since early 2000. We present analysis of Hubble Space Telescope near-ultraviolet (NUV) imaging of the M87 jet from 1999 May to 2006 December that reveals that the NUV intensity of HST-1 has increased 90 times over its quiescent level and outshines the core of the galaxy. The NUV light curve that we derive is synchronous with the light curves derived in other wavebands. The correlation of X-ray and NUV light curves during the HST-1 flare confirms the synchrotron origin of the X-ray emission in the M87 jet. The outburst observed in HST-1 is at odds with the common definition of active galactic nucleus variability usually linked to blazars and originating in close proximity to the central black hole. In fact, the M87 jet is not aligned with our line of sight and HST-1 is located at one million Schwarzchild radii from the supermassive black hole in the core of the galaxy."

History of Observations:

"Nebula without star, in Virgo, below and very near a star of eighth magnitude, the star having the same Right Ascension as the nebula, and its Declination was 13d 42' 21" north. This nebula appears at the same luminosity as the two nebulae Nos. 84 and 86."

"Exceedingly bright; the sharp nucleus shows well in 5m exposure. The brighter central portion is about 0.5' in diameter, and the total diameter is about 2'; nearly round. No spiral structure is discernible. A curious straight ray lies in a gap in the nebulosity in p.a. 20deg, apparently connected with the nucleus by a thin line of matter. The ray is brightest at its inner end, which is 11" from the nucleus. 20 s.n."

Locating Messier 87: