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Keck spectroscopy and spitzer space telescope analysis of the outer disk of the triangulum spiral galaxy M33
IVANIO PUERARI
Acceso Abierto
Atribución-NoComercial-SinDerivadas
In an earlier study of the spiral galaxy M33, we photometrically identified arcs or outer spiral arms of intermediate age (0.6 Gyr − 2 Gyr) carbon stars precisely at the commencement of the HI-warp. Stars in the arcs were unresolved, but were likely thermally-pulsing asymptotic giant branch carbon stars. Here we present Keck I spectroscopy of seven intrinsically bright and red target stars in the outer, northern arc in M33. The target stars have estimated visual magnitudes as faint as V~ 25m. Absorption bands of CN are seen in all seven spectra reported here, confirming their carbon star status. In addition, we present Keck II spectra of a small area 0.5 degree away from the centre of M33; the target stars there are also identified as carbon stars. We also study the non-stellar PAH dust morphology of M33 secured using IRAC on board the Spitzer Space Telescope. The Spitzer 8μm image attests to a change of spiral phase at the start of the HI warp. The Keck spectra confirm that carbon stars may safely be identified on the basis of their red J−Ks colours in the outer, low metallicity disk of M33. We propose that the enhanced number of carbon stars in the outer arms are an indicator of recent star formation, fueled by gas accretion from the HI-warp reservoir.
Astronomy and Astrophysics
2007
Artículo
Inglés
Estudiantes
Investigadores
Público en general
Block, David L., et al., (2007). Keck spectroscopy and spitzer space telescope analysis of the outer disk of the triangulum spiral galaxy M33, Astronomy and Astrophysics, Vol.471(2): 467-474
ASTRONOMÍA Y ASTROFÍSICA
Versión aceptada
acceptedVersion - Versión aceptada
Aparece en las colecciones: Artículos de Astrofísica

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