H I Imaging Observations of Superthin Galaxies. Ii. Ic 2233 and the Blue Compact Dwarf NGC 2537

Abstract

We have used the Very Large Array to image the H i 21 cm line emission in the edge-on Sd galaxy IC 2233 and the blue compact dwarf NGC 2537. We also present new optical B, R, and Hα imaging of IC 2233 obtained with the WIYN telescope. Despite evidence of localized massive star formation in the form of prominent H ii regions and shells, supergiant stars, and a blue integrated color, IC 2233 is a low surface brightness system with a very low global star formation rate ( 0.05 M yr −1 ), and we detect no significant 21 cm radio continuum emission from the galaxy. The H i and ionized gas disks of IC 2233 are clumpy and vertically distended, with scale heights comparable to that of the young stellar disk. Both the stellar and H i disks of IC 2233 appear flared, and we also find a vertically extended, rotationally anomalous component of H i extending to ∼ 2.4d 10 kpc from the midplane. The H i disk exhibits a mild lopsidedness as well as a global corrugation pattern with a period of ∼7d 10 kpc and an amplitude of ∼150d 10 pc. To our knowledge, this is the first time corrugations of the gas disk have been reported in an external galaxy; these undulations may be linked to bending instabilities or to underlying spiral structure and suggest that the disk is largely self-gravitating. Lying at a projected distance of 16 .7 from IC 2233, NGC 2537 has an H i disk with a bright, tilted inner ring and a flocculent, dynamically cold outer region that extends to ∼3.5 times the extent of the stellar light (D 25 ). Although NGC 2537 is rotationally-dominated, we measure H i velocity dispersions as high as σ V ,H i ∼ 25 km s −1 near its center, indicative of significant turbulent motions. The inner rotation curve rises steeply, implying a strong central mass concentration. Our data indicate that IC 2233 and NGC 2537 do not constitute a bound pair and most likely lie at different distances. We also find no compelling evidence of a recent minor merger in either IC 2233 or NGC 2537, suggesting that both are examples of small disk galaxies evolving in relative isolation.

Cold gas accretion in galaxies

“…This value is approximately 15 times lower than the fractional H I content (ratio between gas above 1.4 kpc and gas in the disk) at comparable z-heights in NGC 891. In a similar, superthin LSB galaxy, IC 2233, Matthews and Uson (2008) report a component of "anomalous" extra-planar gas. Also in the LSB galaxy NGC 4395 (see Sect.…”

Study of galaxies in the Lynx-Cancer void - I. Sample description

“…A good TRGB distance estimate is known only for the almost edge‐on LSB spiral IC 2233. We adopt for this galaxy the mean distance modulus of three values discussed by Matthews & Uson (2008): μ mean = 30.15 mag, respectively 10.7 ± 0.5 Mpc. The less accurate NGC 2537 distance estimators are consistent with the galaxies being unrelated (see Matthews & Uson 2008 for references and detailed discussion).…”

“…We adopt for this galaxy the mean distance modulus of three values discussed by Matthews & Uson (2008): μ mean = 30.15 mag, respectively 10.7 ± 0.5 Mpc. The less accurate NGC 2537 distance estimators are consistent with the galaxies being unrelated (see Matthews & Uson 2008 for references and detailed discussion). We adopted for the latter galaxy the distance determined from its radial velocity and general peculiar velocity correction, which appears consistent with estimates in the literature within their accuracies.…”

“…For several objects either without SDSS/NED velocities, or for which this is significantly improved or corrected, we give the latter values. They include PGC 2807187 (Karachentsev et al 2008); pair HS 0822+3542 and SAO 0822+3545, KISSB 23 and SDSS J0926+3343 (Chengalur et al 2006; Pustilnik & Martin 2007; Pustilnik et al 2010); UGC 3912 (Springob et al 2005), SDSS J0723+3621, SDSS J0723+3622, SDSS J0737+4724, SDSS J0852+1351 (Pustilnik et al, in preparation), NGC 2537 and IC 2233 (Matthews & Uson 2008). Column 6.…”

Near‐infrared photometry of superthin edge‐on galaxies

“…A relatively nearby, prototype superthin galaxy UGC 7321 has been well studied (Matthews 2000; Matthews et al 1999; Matthews & Wood 2001; Uson & Matthews 2003). Some more large galaxies with superthin disks have been studied individually using kinematic data (Banerjee & Bapat 2017; Kurapati et al 2018; Matthews & Uson 2008; Mendelowitz et al 2000; O'Brien et al 2010; van der Kruit et al 2001). A few more galaxies with close to the superthin disc scale ratio have been studied in the middle infrared in the frames of the S 4 G survey (Salo et al 2015).…”