Resolving the stellar population of the standard elliptical galaxy NGC 3379

Michael D. Gregg, Henry C. Ferguson, Dante Minniti, Nial Tanvir, Robin Catchpole

Resultado de la investigación: Article

30 Citas (Scopus)

Resumen

Using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on board the Hubble Space Telescope, we have obtained F110W (∼J) and F160W (∼H) images of three fields in NGC 3379, a nearby normal giant elliptical galaxy. These images resolve individual red giant stars, yielding the first accurate color-magnitude diagrams for a normal luminous elliptical galaxy. The photometry reaches ∼1 mag below the red giant branch (RGB) tip with errors of ≲0.2 mag in F110W-F160W. A strong break in the luminosity function at F160W = 23.68±0.06 is identified as the tip of the red giant branch; comparison with theoretical isochrones implies a distance of 10.8±0.6 Mpc, in good agreement with a number of previous estimates using various techniques. The mean metallicity is close to solar, but there is an appreciable spread in abundance, from at least as metal-poor as [Fe/H]≈ -1.5 to as high as +0.8. There is a significant population of stars brighter than the RGB tip by up to ∼1 mag. The observations of each field were split over two epochs separated by 2-3 months, allowing the identification of candidate long-period variables; at least 40% of the stars brighter than the RGB tip are variable. Lacking period determinations, the exact nature of these variables remains uncertain, but the bright AGB stars and variables are similar to those found in metal-rich globular clusters and are not luminous enough to imply an intermediate-age population. All of the evidence points to a stellar population in NGC 3379 that is very similar to the bulge of the Milky Way, or an assortment of Galactic globular clusters covering a large metallicity spread.

Idioma originalEnglish
Páginas (desde-hasta)1441-1459
Número de páginas19
PublicaciónAstronomical Journal
Volumen127
N.º3 1779
DOI
EstadoPublished - mar 2004

Huella dactilar

elliptical galaxies
metal
globular clusters
metallicity
near infrared
spectrometer
diagram
red giant stars
Mira variables
stars
color-magnitude diagram
asymptotic giant branch stars
Hubble Space Telescope
metals
photometry
coverings
cameras
luminosity
time measurement
spectrometers

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Citar esto

Gregg, M. D., Ferguson, H. C., Minniti, D., Tanvir, N., & Catchpole, R. (2004). Resolving the stellar population of the standard elliptical galaxy NGC 3379. Astronomical Journal, 127(3 1779), 1441-1459. https://doi.org/10.1086/381951
Gregg, Michael D. ; Ferguson, Henry C. ; Minniti, Dante ; Tanvir, Nial ; Catchpole, Robin. / Resolving the stellar population of the standard elliptical galaxy NGC 3379. En: Astronomical Journal. 2004 ; Vol. 127, N.º 3 1779. pp. 1441-1459.
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abstract = "Using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on board the Hubble Space Telescope, we have obtained F110W (∼J) and F160W (∼H) images of three fields in NGC 3379, a nearby normal giant elliptical galaxy. These images resolve individual red giant stars, yielding the first accurate color-magnitude diagrams for a normal luminous elliptical galaxy. The photometry reaches ∼1 mag below the red giant branch (RGB) tip with errors of ≲0.2 mag in F110W-F160W. A strong break in the luminosity function at F160W = 23.68±0.06 is identified as the tip of the red giant branch; comparison with theoretical isochrones implies a distance of 10.8±0.6 Mpc, in good agreement with a number of previous estimates using various techniques. The mean metallicity is close to solar, but there is an appreciable spread in abundance, from at least as metal-poor as [Fe/H]≈ -1.5 to as high as +0.8. There is a significant population of stars brighter than the RGB tip by up to ∼1 mag. The observations of each field were split over two epochs separated by 2-3 months, allowing the identification of candidate long-period variables; at least 40{\%} of the stars brighter than the RGB tip are variable. Lacking period determinations, the exact nature of these variables remains uncertain, but the bright AGB stars and variables are similar to those found in metal-rich globular clusters and are not luminous enough to imply an intermediate-age population. All of the evidence points to a stellar population in NGC 3379 that is very similar to the bulge of the Milky Way, or an assortment of Galactic globular clusters covering a large metallicity spread.",
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Gregg, MD, Ferguson, HC, Minniti, D, Tanvir, N & Catchpole, R 2004, 'Resolving the stellar population of the standard elliptical galaxy NGC 3379', Astronomical Journal, vol. 127, n.º 3 1779, pp. 1441-1459. https://doi.org/10.1086/381951

Resolving the stellar population of the standard elliptical galaxy NGC 3379. / Gregg, Michael D.; Ferguson, Henry C.; Minniti, Dante; Tanvir, Nial; Catchpole, Robin.

En: Astronomical Journal, Vol. 127, N.º 3 1779, 03.2004, p. 1441-1459.

Resultado de la investigación: Article

TY - JOUR

T1 - Resolving the stellar population of the standard elliptical galaxy NGC 3379

AU - Gregg, Michael D.

AU - Ferguson, Henry C.

AU - Minniti, Dante

AU - Tanvir, Nial

AU - Catchpole, Robin

PY - 2004/3

Y1 - 2004/3

N2 - Using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on board the Hubble Space Telescope, we have obtained F110W (∼J) and F160W (∼H) images of three fields in NGC 3379, a nearby normal giant elliptical galaxy. These images resolve individual red giant stars, yielding the first accurate color-magnitude diagrams for a normal luminous elliptical galaxy. The photometry reaches ∼1 mag below the red giant branch (RGB) tip with errors of ≲0.2 mag in F110W-F160W. A strong break in the luminosity function at F160W = 23.68±0.06 is identified as the tip of the red giant branch; comparison with theoretical isochrones implies a distance of 10.8±0.6 Mpc, in good agreement with a number of previous estimates using various techniques. The mean metallicity is close to solar, but there is an appreciable spread in abundance, from at least as metal-poor as [Fe/H]≈ -1.5 to as high as +0.8. There is a significant population of stars brighter than the RGB tip by up to ∼1 mag. The observations of each field were split over two epochs separated by 2-3 months, allowing the identification of candidate long-period variables; at least 40% of the stars brighter than the RGB tip are variable. Lacking period determinations, the exact nature of these variables remains uncertain, but the bright AGB stars and variables are similar to those found in metal-rich globular clusters and are not luminous enough to imply an intermediate-age population. All of the evidence points to a stellar population in NGC 3379 that is very similar to the bulge of the Milky Way, or an assortment of Galactic globular clusters covering a large metallicity spread.

AB - Using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on board the Hubble Space Telescope, we have obtained F110W (∼J) and F160W (∼H) images of three fields in NGC 3379, a nearby normal giant elliptical galaxy. These images resolve individual red giant stars, yielding the first accurate color-magnitude diagrams for a normal luminous elliptical galaxy. The photometry reaches ∼1 mag below the red giant branch (RGB) tip with errors of ≲0.2 mag in F110W-F160W. A strong break in the luminosity function at F160W = 23.68±0.06 is identified as the tip of the red giant branch; comparison with theoretical isochrones implies a distance of 10.8±0.6 Mpc, in good agreement with a number of previous estimates using various techniques. The mean metallicity is close to solar, but there is an appreciable spread in abundance, from at least as metal-poor as [Fe/H]≈ -1.5 to as high as +0.8. There is a significant population of stars brighter than the RGB tip by up to ∼1 mag. The observations of each field were split over two epochs separated by 2-3 months, allowing the identification of candidate long-period variables; at least 40% of the stars brighter than the RGB tip are variable. Lacking period determinations, the exact nature of these variables remains uncertain, but the bright AGB stars and variables are similar to those found in metal-rich globular clusters and are not luminous enough to imply an intermediate-age population. All of the evidence points to a stellar population in NGC 3379 that is very similar to the bulge of the Milky Way, or an assortment of Galactic globular clusters covering a large metallicity spread.

KW - Galaxies: elliptical and lenticular, cD

KW - Galaxies: stellar content

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