Interactive Deconvolution with Error Analysis (IDEA) 
in astronomical imaging: Application to
aberrated HST images on SN 1987A, M 87 and 
3C 66B

Bouyoucef, Karim; Fraix-Burnet, Didier; Roques, S.

doi:10.1051/aas:1997128

Cited by 2 publications

(1 citation statement)

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“…Our approach is motivated by the need to extract information from objects which are only slightly resolved and to contend with the undersampling of the PC2. Both of these effects limit the ability to uniquely reconstruct brightness distributions of small angular size sources, such as nuclei (e.g., Wildey 1992;Bouyoucef et al 1997). For non-active or weakly active nuclei, our models are motivated physically by the structure of the Milky Way nucleus (e.g., Mezger et al 1996) as it would appear at larger distances.…”

Section: Model Fitsmentioning

confidence: 99%

WFPC2 Observations of Compact Star Cluster Nuclei in Low-Luminosity Spiral Galaxies

Matthews

Gallagher

Krist

et al. 1999

The Astronomical Journal

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We have used the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope to obtain F 450W and F 814W (B-and I-band) observations of the compact star cluster nuclei of the nearby, late-type, low-luminosity spiral galaxies NGC 4395, NGC 4242,. In addition, we analyze archival WFPC2 observations of the compact star cluster nucleus of M33. All of these galaxies are structurally diffuse, with moderately low surface brightnesses and little or no discernible bulge component. Here we present a comparative analysis of the structural and photometric properties of their nuclei. NGC 4395 contains a Seyfert 1 nucleus; M33 has some signatures of weak nuclear activity; the other two galaxies are not known to be active. All of the nuclei have M I ∼ −11, hence these represent a little explored low-luminosity extension of the galactic nuclear activity sequence in a class of host galaxy not traditionally associated with galactic nuclear phenomena. These kinds of compact nuclei appear to be quite common in low luminosity, late-type spirals.Our Planetary Camera 2 images partially resolve the nuclei of all four galaxies. A simple model consisting of an isothermal sphere plus a point source provides a good model for the observed radial intensity distribution in all cases and permits an exploration of the underlying nuclear structures and spatial scales. Despite their low -3luminosities, all of the nuclei are very compact. In all cases the luminosity densities are increasing to the resolution limit of our data at small radii. In spite of having similar size scales and luminosities, the nuclei in our sample span a wide range of B − I color. This may be a signature of different evolutionary phases in structurally similar nuclei.The M33 nucleus exhibits complex structure; its isophotes are elongated, and it has a jet-like component. The Seyfert nucleus of NGC 4395 has an extremely blue color (B − I = −0.16) and is the most structurally complex nucleus in our sample. Circularly symmetric fits to its underlying structure reveal a distinct bipolar pattern. A pair of bright filaments located on one side of the nucleus are probably due to [O iii] emission from gas within a nuclear ionization cone. NGC 4395 appears to contain an underlying normal star cluster nucleus that is hosting activity.NGC 4242 shows evidence of a slightly elongated, bar-shaped feature at its center. The ESO 359-029 nucleus appears relatively symmetric and featureless at the resolution limit of our data, but it is clearly very compact.The circumnuclear environments of all four of our program galaxies are extremely diffuse, have only low to moderate star formation, and appear to be devoid of large quantities of dust. The central gravitational potentials of the galaxies are also quite shallow, making the origin of these types of "naked" nuclei problematic.14 Ho=75 km s −1 Mpc −1 is assumed throughout this work.

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Section: Model Fitsmentioning

confidence: 99%