Properties of Spiral-Peculiar Type of Kiso Ultraviolet-Excess Galaxies

Abstract

We investigated the optical spectroscopic properties of 44 Kiso Ultraviolet-excess Galaxies (KUG), which is one of the most well-known catalogs of blue galaxies. All of our sample galaxies belong to the spiral-peculiar (Sp) type, the morphological class of spiral galaxy with a peculiar bar and/or a nucleus in KUGs. Since the Sp type is considered to be the most peculiar group among KUGs, and about 45% of the KUGs have the Sp type, a detailed study of the Sp type is crucial to understand the characteristics of the KUG. The sample galaxies have luminosities in the $ B$–band of about $ 10^{8}$ to less than $ 10^{10}$ in solar unit, and a median physical size of 13 kpc. From the nuclear spectra, we determined line excitation sources in 39 galaxies. Among them, we detected four AGNs reliably: two Seyfert 1s, one Seyfert 2, and one LINER. Other sample galaxies show moderately star-forming activity. For this category of ordinary KUG group, the mode of the $ \mathrm{H}\alpha$ equivalent width at the nuclear region is a bin of 40 to 60 Å. Three galaxies have extreme starburst nuclei with an $ \mathrm{H}\alpha$ equivalent width of more than 200 Å. The internal extinction of $ A_{V}$ is about 0.8 mag, which suggests that the star-forming nuclei are not heavily enshrouded by dust.

Active and Star-forming Galaxies and Their Supernovae

“…These galaxies have been identified as UVor emission-line galaxies from the Kiso (e.g., Takase & MiyauchiIsobe 1985), Mrk (Markarian et al 1989), KISS (e.g., Salzer et al 2002), Wasilewski (1983), and other surveys of active and star-forming objects or are known peculiar galaxies according to their morphological structure (e.g., NGC 2608 in the sample is Arp 12), or integral properties (e.g., NGC 2415 in the sample is the high surface brightness galaxy Haro 1 = Ark 136). The inclusion in the sample of galaxies with peculiar morphologies and/or integral properties, which very often are the outcomes of merging or close interaction, follows the wide belief that, in general, star formation or nuclear activity in these galaxies is enhanced (e.g., Tomita & Maehara 2002;Malkan & Hunt 2004). For more details, see Petrosian et al (2005a);…”

The North Galactic Pole +30° Zone Galaxies. I. A Comparative Study of Galaxies with Different Nuclear Activity

“…Cross-checking also includes the lists of known peculiar morphological structure galaxies (e.g., NGC 2608 in the sample is Arp 12), or lists of galaxies with peculiar integral properties (e.g., NGC 2415 in the sample is the high surface brightness galaxy Haro 1 = Ark 136). The inclusion of galaxies with peculiar morphologies and /or integral properties, which very often are the outcomes of merging or close interaction, follows the general evidence of enhanced star formation or nuclear activity in these galaxies (e.g., Tomita & Maehara 2002;Malkan & Hunt 2004). In this respect, the A/SF galaxies sample also includes galaxies which according to our study have been morphologically classified as mergers or close interacting systems.…”