Volume 519, September 2010
|Number of page(s)||16|
|Published online||10 September 2010|
Near-infrared and optical observations of galactic warps: a common, unexplained feature of most discs
Dpto. Física Teórica y del Cosmos, Universidad de Granada, Granada, Spain e-mail: firstname.lastname@example.org
2 Centro Astronómico Hispano Alemán, Almería, Spain
3 Kapteyn Astronomical Institute, Groningen, The Netherlands
4 Kavli Institute for Astronomy and Astrophysics and Department of Astronomy, Peking University, Beijing, PR China
5 Department of Physics & Astronomy, The University of Sheffield, UK
Accepted: 10 June 2010
Context. Warps occurring in galactic discs have been studied extensively in HI and in the optical, but rarely in the near-infrared (NIR) bands that trace the older stellar populations.
Aims. We provide NIR data of nearby edge-on galaxies, combined with optical observations, for direct comparison of the properties of galactic warps as a function of wavelength, and calculate warp curves for each galaxy and obtain the characteristic warp parameters. We discuss these properties as possible constraints to the different mechanisms that have been proposed for the development and persistence of galactic warps.
Methods. We observed 20 galaxies that were selected from a statistically complete diameter-limited subsample of edge-on disc galaxies. We used the Cerro Tololo Infrared Imager (CIRIM) at the CTIO 1.5 m Ritchey-Chretien telescope to acquire the NIR data. We used the 1.54 m Danish and 0.92 m Dutch telescopes at the European Southern Observatory's La Silla site for our optical observations.
Results. Our results show that 13 of our 20 sample galaxies are warped, with the warp more pronounced in the optical than at NIR wavelengths. In the remaining seven galaxies, no warp is apparent within the limitations of our automated detection method. The transition between the unperturbed inner disc and the outer, warped region is rather abrupt. S0 galaxies exhibit very small or no warps. The magnetic model remains one of a number of interesting formation scenarios.
Key words: galaxies: general / galaxies: photometry / galaxies: structure
© ESO, 2010
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.