318 research outputs found
High-resolution UKIRT observations of circumnuclear star formation in M100
We present high-resolution, near-infrared imaging of the circumnuclear region
of the barred spiral galaxy M100 (=NGC 4321), accompanied by near-infrared
spectroscopy. We identify a total of 43 distinct regions in the K-band image,
and determine magnitudes and colours for 41 of them. By comparison with other
near-infrared maps we also derive colour excesses and K-band extinctions for
the knots. Combining the imaging and spectroscopic results, we conclude that
the knots are the result of bursts of star formation within the last 15-25 Myr.
We discuss the implications of these new results for our dynamical and
evolutionary understanding of this galaxy.Comment: 10 pages, 4 figures, uses mn-1.4.sty. Accepted for publication in
Monthly Notices of the Royal Astronomical Societ
Origin and fate of organic matter in South-West Australian wetlands
The development and local distribution of organic soils in Australia have been poorly documented. Within Western Australia, conditions conducive to the accumulation of organic matter are geographically restricted and generally occur in coastal and/or forested landscapes. An extensive system of wetlands with peal soils occurs in the Muir-Unicup region in the far south west of Western Australia. Bokarup Swamp, Kodjinup Swamp and Noobijup Lake are representative of the wetlands occurring in this region. They arc shallow
A postmortem investigation of the Type IIb supernova 2001ig
We present images taken with the GMOS instrument on Gemini-South, in
excellent (<0.5 arcsec) seeing, of SN 2001ig in NGC 7424, ~1000 days after
explosion. A point source seen at the site of the SN is shown to have colours
inconsistent with being an H II region or a SN 1993J-like remnant, but can be
matched to a late-B through late-F supergiant with A_V<1. We believe this
object is the massive binary companion responsible for periodic modulation in
mass loss material around the Wolf-Rayet progenitor which gave rise to
significant structure in the SN radio light curve.Comment: 5 pages, 3 figures. Accepted for publication in MNRAS Letters. Fig. 1
resolution degraded to meet size limitations; full resolution version
available from http://www.aao.gov.au/local/www/sdr/pubs/sn2001ig_gmos.ps.g
A SINFONI view of circum-nuclear star-forming rings in spiral galaxies
We present near-infrared (H- and K-band) SINFONI integral-field observations
of the circumnuclear star formation rings in five nearby spiral galaxies. We
made use of the relative intensities of different emission lines (i.e. [FeII],
HeI, Brg) to age date the stellar clusters present along the rings. This
qualitative, yet robust, method allows us to discriminate between two distinct
scenarios that describe how star formation progresses along the rings. Our
findings favour a model where star formation is triggered predominantly at the
intersection between the bar major axis and the inner Lindblad resonance and
then passively evolves as the clusters rotate around the ring ('Pearls on a
string' scenario), although models of stochastically distributed star formation
('Popcorn' model) cannot be completely ruled out.Comment: 4 pages, 3 figures, contribution to the Proceedings of the IAU
Symposium 245, "Formation and Evolution of Galaxy Bulges", held at Oxford,
U.K., July 2007, Eds. M. Bureau, E. Athanassoula, B. Barbu
- …