Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published March 10, 1991 | Published
Journal Article Open

The core of the nearby S0 galaxy NGC 7457 imaged with the HST planetary camera


We have observed the nearby S0 galaxy NGC 7457 with the Planetary Camera of the Hubble Space Telescope. Spatial structure is observable at the diffraction-limited resolution of the 2.4 m HST primary despite the effects of spherical aberration. The central distribution of starlight appears consistent with a y ~ -1.0 power law for r < 600 pc, plus a possible additional stellar nucleus with L - 1 x 10^7 L_☉ (V band). We find no evidence of a core to limits r_c <0".052 = 3.4 pc (H_0 = 80 km s^(-1) Mpc^(-1)), in contrast to a priori estimates of r_c ~ 30 pc based on total galaxy luminosity. The center of NGC 7457 remains unresolved at HST resolution and has a central luminosity density p_0 > 3 x 10^4 L_☉ pc^(-3) (V band). This is now the second densest core known after M32. From the ground, NGC 7457 resembles any number of unresolved elliptical galaxies, which suggests that compact dense cores may be common. The images of NGC 7457 demonstrate that HST can still provide unique and astrophysically interesting information on the central structure of galaxies.

Additional Information

© 1991 American Astronomical Society. Received 1990 October 1; accepted 1990 November 19. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. This research was conducted by the WFPC Investigation Definition Team operating under partial support from NASA contract NAS 5-25421.

Attached Files

Published - 1991ApJ___369L__41L.pdf


Files (1.8 MB)
Name Size Download all
1.8 MB Preview Download

Additional details

August 19, 2023
October 18, 2023