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The galaxy IC 2554

The galaxy IC2554

Bärbel Koribalski (ATNF)

ATCA HI Observations of the Peculiar Galaxy IC2554

Bärbel Koribalski (ATNF),
Scott Gordon (Universty of Queensland; ATNF)
Keith Jones (Universty of Queensland)

(2003) MNRAS 339, 1203 (download pdf file)

Abstract. ATCA HI and radio continuum observations of the peculiar southern galaxy IC2554 and its surroundings reveal typical signatures of an interacting galaxy group. We detected a large HI cloud between IC2554 and the elliptical galaxy NGC3136B. The gas dynamics in IC2554 itself, which is sometimes described as a colliding pair, are surprisingly regular, whereas NGC3136B was not detected. The HI cloud, which emerges from IC2554 as a large arc-shaped plume, has a size of approx. 30 kpc, larger than that of IC2554. The total HI mass of the IC2554 system is approx. 2 x 10⁹ Msun, a third of which resides in the HI cloud. It is possible that tidal interaction between IC2554 and NGC3136B caused this spectacular HI cloud, but the possibility of IC2554 being a merger remnant is also discussed. We also detected HI gas in the nearby galaxies ESO092-G009 and RKK1959 as well as an associated HI cloud, ATCA J1006-6710. Together they have an HI mass of approx. 4.6 x 10⁸ Msun. Another new HI source, ATCA J1007-6659, with an HI mass of only approx. 2.2 x 10⁷ Msun was detected roughly between IC2554 and ESO092-G009 and corresponds to a face-on low surface brightness dwarf galaxy. Star formation is evident only in the galaxy IC2554 with a rate of approx. 4 Msun/yr.

Overlay of the HI distribution of the peculiar galaxy system IC2554 onto an optical and infrared images from DSS2 and 2MASS, respectively.

IC2554 and surroundings were observed with the ATCA by Scott Gordon et al. as part of his PhD Thesis (2002, University of Queensland). The ATCA field consists of

the peculiar galaxy IC2554 (v_HI = 1378+-9 km/s; various measurements for v_opt = 1240 to 1850 km/s),
a large tidal HI plume emerging from IC2554 and extending like a big arc towards the East,
and the elliptical galaxy NGC3136B (v_opt = 1780+-31 km/s), at a distance of 8.2' from IC2554, not detected in HI.
At a distance of 16.5' from IC2554 we detected the galaxy ESO092-G009 at v_HI (ATCA) = 1450 km/s (v_opt = ?), RKK 1959 at v_HI (ATCA) = 1610 km/s (v_opt = ?) and an HI cloud, named ATCA J1006-6710, at v_HI (ATCA) = 1720 km/s.
For details see the paper by Koribalski, Gordon, & Jones (2003, MNRAS 339, 1203 )

Displayed below are some ATCA HI images:

Figure 1a: HI distribution of the peculiar galaxy IC2554 and its surroundings (primary beam corrected). The 30" beam is displayed at the bottom left.

Figure 1b: HI peak flux distribution of the peculiar galaxy IC2554 and its surroundings (primary beam corrected). The 30" beam is displayed at the bottom left.

Figure 1c: Mean HI velocity field of the peculiar galaxy IC2554 and its surroundings. The 30" beam is displayed at the bottom left.

Figure 1d: DSS optical image of the peculiar galaxy IC2554 and its surroundings.

Displayed below are HI images obtained from HIPASS:

Figure 2a: HI distribution (contours) overlaid onto the DSS optical image of the galaxy IC2554 and surroundings.

Figure 2b: HI distribution of the galaxy IC2554 and surroundings.

Figure 2c: Mean HI velocity field of the galaxy IC2554 and surroundings.

bkoribal@atnf.csiro.au