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Star-forming knots and density wave in NGC 2997

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Star-forming knots and density wave in NGC 2997

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Título Star-forming knots and density wave in NGC 2997
Autor Grosbol, Preben
Dottori, Horacio Alberto
Gredel, Roland
Abstract Context. Many grand design spiral galaxies show strings of bright knots along their arms on near-infrared K-band images. The alignment of such knots suggests a relation to the spiral pattern and possibly to a large-scale, star-forming front associated with a density wave. Aims. Bright knots in the southern arm of NGC 2997 were studied to determine their nature and evolutionary state. Methods. Low resolution near-infrared K- and J-band spectra of the knots were observed with ISAAC on the VLT. Results. Most of the knots show strong Hi Brγ emission with some also having He i and H2 emission. A few knots show indications of 12CO absorption. This suggests that the knots are very young stellar clusters with masses up to 5 × 104 Mʘ. Conclusions. The knots azimuthal distance from the K-band spiral correlates well with their Brγ strength, indicating that they are located inside the co-rotation of the density wave, which triggered them through a large-scale, star-forming front. These relative azimuthal distances suggest an age spread of more than 1.6Myr, which is incompatible with standard models for an instantaneous star burst. This indicates a more complex star-formation history, such as several bursts or continuous formation.
Contido em Astronomy and astrophysics. Les Ulis. Vol. 453, no. 2 (July 2006), p. L25-L28
Assunto Aglomerados estelares
Galaxias espirais
[en] Galaxies: individual: NGC 2997
[en] Galaxies: spiral
[en] Galaxies: star clusters
[en] Galaxies: structure
[en] Infrared: galaxies
[en] Techniques: spectroscopic
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/98860
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