HST Planetary Camera 2 Imaging of the Nuclei of the Low-Luminosity, Late-Type Spirals NGC 4242 and NGC 4395

Session 4 - Low Luminosity AGN and Starburst Galaxies.
Display session, Monday, June 10
Tripp Commons,

[4.03] HST Planetary Camera 2 Imaging of the Nuclei of the Low-Luminosity, Late-Type Spirals NGC 4242 and NGC 4395

L. D. Matthews (SUNY at Stony Brook), J. S. Gallagher III (U. Wisconsin, Madison), J. Krist, C. Burrows (STScI), W. Idt

Low luminosity, late-type (Scd-Sm) spiral galaxies sometimes contain compact nuclei which appear semi-stellar at ground-based resolutions. Studies of the nature of these nuclei and their relationship to the active nuclei in more luminous galaxies can be undertaken through the use of high-resolution imaging capabilities of the Planetary Camera 2 (PC 2) on the Hubble Space Telescope. Here we present a comparative study of the nuclei of the low-luminosity, late-type spirals NGC 4395 (SAdm) and NGC 4242 (SABdm) using new HST PC 2 images in the F450W and F814W filters in combination with existing multiwavelength data from the literature. The nucleus of NGC 4395 was discovered by Filippenko amp; Sargent (1989; ApJL 342, L11) to be the lowest luminosity Seyfert 1 known. Our new data confirm the existence of slightly extended emission (probably [O \sc iii]) first noted by Filippenko et al. (1993; ApJL, 410, L75) as well as a large filament associated with a possible bi-polar structure. The nucleus of the non-active galaxy NGC 4242 remains a near-stellar object in our PC 2 data. We discuss these results in terms of the starburst and AGN models for the activity in NGC 4395.

Program listing for Monday