Unlocking the secrets of stellar haloes using combined star counts and surface photometry
2012 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 421, no 1, 190-201 p.Article in journal (Refereed) Published
The stellar haloes of galaxies can currently be studied either throughobservations of resolved halo stars or through surface photometry.Curiously, the two methods appear to give conflicting results, asa number of surface photometry measurements have revealed integratedcolours that are too red to be reconciled with the halo propertiesinferred from the study of resolved stars. Several explanations forthis anomaly have been proposed - including dust photoluminescence,extinction of extragalactic background light and a bottom-heavy stellarinitial mass function. A decisive test is, however, still lacking.Here, we explain how observations of the halo of a nearby galaxy,involving a combination of both surface photometry and bright starcounts, can be used to distinguish between the proposed explanations.We derive the observational requirements for this endeavour and findthat star counts in filters VI and surface photometry in filtersVIJ appear to be the optimal strategy. Since the required halo starcounts are already available for many nearby galaxies, the most challengingpart of this test is likely to be the optical surface photometry,which requires several nights of exposure time on a 4-8 m telescope,and the near-infrared surface photometry, which is most readily carriedout using the upcoming James Webb Space Telescope.
Place, publisher, year, edition, pages
2012. Vol. 421, no 1, 190-201 p.
dust, extinction, galaxies: haloes, galaxies: photometry, diffuse radiation
Astronomy, Astrophysics and Cosmology
Research subject Astronomy
IdentifiersURN: urn:nbn:se:su:diva-75815DOI: 10.1111/j.1365-2966.2011.20290.xISI: 000302693600046OAI: oai:DiVA.org:su-75815DiVA: diva2:524113