Volume 567, July 2014
|Number of page(s)||9|
|Published online||10 July 2014|
A ~ 12 kpc H i extension and other H i asymmetries in the isolated galaxy CIG 340 (IC 2487)⋆
1 Instituto de Astrofísica de Andalucía (IAA/CSIC), Apdo. 3004, 18080 Granada, Spain
2 Centre for Astrophysics Research, University of Hertfordshire, , College Lane, Hatfield, AL10 9AB, UK
3 Korea Astronomy and Space Science Institute, , 776, Daedeokdae-ro, Yuseong-gu, 305-348 Daejeon, Republic of Korea
4 Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, , 13388 Marseille, France
5 Joint ALMA Observatory (ALMA/ESO), , Alonso de Córdova 3107, Vitacura, 763-0355 Santiago, Chile
6 National Astronomical Observatory of Japan (NAOJ), , 2-21-1 Osawa, Mitaka, 181-8588 Tokyo, Japan
7 The Graduate University for Advanced Studies (SOKENDAI), , 2-21-1 Osawa, Mitaka, 181-8588 Tokyo, Japan
8 Department of Astronomy, University of Massachusetts, , 710 North Pleasant Street, Amherst, MA 01003, USA
Received: 23 February 2014
Accepted: 9 May 2014
Context. H i kinematic asymmetries are common in late-type galaxies irrespective of environment, although the amplitudes are strikingly low in isolated galaxies. As part of our studies of the H i morphology and kinematics in isolated late–type galaxies we have chosen several very isolated galaxies from the AMIGA sample for H i mapping. We present here the results of H i mapping of CIG 340 (IC 2487) which was selected because its integrated H i spectrum has a very symmetric profile (Aflux = 1.03 ± 0.02).
Aims. Optical images of the galaxy hinted at a warped disk in contrast to the symmetric integrated H i spectrum profile. Our aim is to determine the extent to which the optical asymmetry is reflected in the resolved H i morphology and kinematics.
Methods. Resolved 21-cm H i line mapping has been carried out using the Giant Metrewave Radio Telescope (GMRT). The H i morphology and kinematics from this mapping together with other multi-wavelength data have been used to study the relationship between the H i and stellar components of CIG 340.
Results. GMRT observations reveal significant H i morphological asymmetries in CIG 340 despite it’s overall symmetric optical form and highly symmetric H i spectrum. The most notable H i features are: 1) a warp in the H i disk (with an optical counterpart), 2) the H i north/south flux ratio = 1.32 is much larger than expected from the integrated H i spectrum profile, and 3) a ~ 45′′ (12 kpc) H i extension containing ~6% of the detected H i mass on the northern side of the disk.
Conclusions. Overall, we conclude that in isolated galaxies a highly symmetric H i spectrum can mask significant H i morphological asymmetries which can be revealed by H i interferometric mapping. The northern H i extension appears to be the result of a recent perturbation (108 yr), possibly by a satellite which is now disrupted or projected within the disk. But, we cannot rule out that the H i extension and the other observed asymmetries are the result of a long lived dark matter halo asymmetry. This study provides an important step in our ongoing programme to determine the predominant source of H i asymmetries in isolated galaxies. For CIG 340 the isolation from major companions, symmetric H i spectrum, optical morphology and interaction timescales have allowed us to narrow the possible causes the H i asymmetries and identify tests to further constrain the source of the asymmetries.
Key words: galaxies: individual: CIG 340 (IC 2487) / galaxies: ISM / radio lines: galaxies
H i datacubes are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A56
© ESO, 2014
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.