The resolved stellar populations of a dwarf spheroidal galaxy in the virgo cluster

Patrick R. Durrell, Benjamin F. Williams, Robin Ciardullo, John J. Feldmeier, Ted Von Hippel, Steinn Sigurdsson, George H. Jacoby, Henry C. Ferguson, Nial R. Tanvir, Magda Arnaboldi, Ortwin Gerhard, J. Alfonso L. Aguerri, Ken Freeman, Matt Vinciguerra

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

We report on the disco very of a faint (MV ∼ -10.6 ± 0.2)dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends ≳1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepest CMD for a small dwarf galaxy inside a cluster environment. Using the colors of the RGB stars, we derive a metal abundance for the dwarf of [M/H] = -2,3 ± 0.3 and show that the metallicity dispersion is less than 0.6 dex at 95% confidence. We also use the galaxy's lack of AGB stars and the absence of objects brighter than Mbol ∼ -4.1 ∼ 0.2 to show that the system is old (t ≳ 10 Gyr). Finally, we derive the object's structural parameters and show that the galaxy displays no obvious evidence of tidal threshing. Since the tip of the red giant branch distance [(m - M)0 = 31.23 ± 0.17 or D = 17.6 ± 1.4 Mpc] puts the galaxy near the core of the Virgo cluster, one might expect the object to have undergone some tidal processing. Yet the chemical and morphological similarity between the dwarf and the dSph galaxies of the Local and M81 Group demonstrates that the object is indeed pristine and not the shredded remains of a much larger galaxy. We discuss the possible origins of this galaxy and suggest that it is just now falling into Virgo for the first time.

Original languageEnglish (US)
Pages (from-to)746-755
Number of pages10
JournalAstrophysical Journal
Volume656
Issue number2 I
DOIs
StatePublished - Feb 20 2007

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dwarf galaxies
galaxies
diagram
color-magnitude diagram
metal
asymptotic giant branch stars
falling
Hubble Space Telescope
metallicity
confidence
color
stars
metals

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Durrell, P. R., Williams, B. F., Ciardullo, R., Feldmeier, J. J., Von Hippel, T., Sigurdsson, S., ... Vinciguerra, M. (2007). The resolved stellar populations of a dwarf spheroidal galaxy in the virgo cluster. Astrophysical Journal, 656(2 I), 746-755. https://doi.org/10.1086/510714
Durrell, Patrick R. ; Williams, Benjamin F. ; Ciardullo, Robin ; Feldmeier, John J. ; Von Hippel, Ted ; Sigurdsson, Steinn ; Jacoby, George H. ; Ferguson, Henry C. ; Tanvir, Nial R. ; Arnaboldi, Magda ; Gerhard, Ortwin ; Aguerri, J. Alfonso L. ; Freeman, Ken ; Vinciguerra, Matt. / The resolved stellar populations of a dwarf spheroidal galaxy in the virgo cluster. In: Astrophysical Journal. 2007 ; Vol. 656, No. 2 I. pp. 746-755.
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abstract = "We report on the disco very of a faint (MV ∼ -10.6 ± 0.2)dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends ≳1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepest CMD for a small dwarf galaxy inside a cluster environment. Using the colors of the RGB stars, we derive a metal abundance for the dwarf of [M/H] = -2,3 ± 0.3 and show that the metallicity dispersion is less than 0.6 dex at 95{\%} confidence. We also use the galaxy's lack of AGB stars and the absence of objects brighter than Mbol ∼ -4.1 ∼ 0.2 to show that the system is old (t ≳ 10 Gyr). Finally, we derive the object's structural parameters and show that the galaxy displays no obvious evidence of tidal threshing. Since the tip of the red giant branch distance [(m - M)0 = 31.23 ± 0.17 or D = 17.6 ± 1.4 Mpc] puts the galaxy near the core of the Virgo cluster, one might expect the object to have undergone some tidal processing. Yet the chemical and morphological similarity between the dwarf and the dSph galaxies of the Local and M81 Group demonstrates that the object is indeed pristine and not the shredded remains of a much larger galaxy. We discuss the possible origins of this galaxy and suggest that it is just now falling into Virgo for the first time.",
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Durrell, PR, Williams, BF, Ciardullo, R, Feldmeier, JJ, Von Hippel, T, Sigurdsson, S, Jacoby, GH, Ferguson, HC, Tanvir, NR, Arnaboldi, M, Gerhard, O, Aguerri, JAL, Freeman, K & Vinciguerra, M 2007, 'The resolved stellar populations of a dwarf spheroidal galaxy in the virgo cluster', Astrophysical Journal, vol. 656, no. 2 I, pp. 746-755. https://doi.org/10.1086/510714

The resolved stellar populations of a dwarf spheroidal galaxy in the virgo cluster. / Durrell, Patrick R.; Williams, Benjamin F.; Ciardullo, Robin; Feldmeier, John J.; Von Hippel, Ted; Sigurdsson, Steinn; Jacoby, George H.; Ferguson, Henry C.; Tanvir, Nial R.; Arnaboldi, Magda; Gerhard, Ortwin; Aguerri, J. Alfonso L.; Freeman, Ken; Vinciguerra, Matt.

In: Astrophysical Journal, Vol. 656, No. 2 I, 20.02.2007, p. 746-755.

Research output: Contribution to journalArticle

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T1 - The resolved stellar populations of a dwarf spheroidal galaxy in the virgo cluster

AU - Durrell, Patrick R.

AU - Williams, Benjamin F.

AU - Ciardullo, Robin

AU - Feldmeier, John J.

AU - Von Hippel, Ted

AU - Sigurdsson, Steinn

AU - Jacoby, George H.

AU - Ferguson, Henry C.

AU - Tanvir, Nial R.

AU - Arnaboldi, Magda

AU - Gerhard, Ortwin

AU - Aguerri, J. Alfonso L.

AU - Freeman, Ken

AU - Vinciguerra, Matt

PY - 2007/2/20

Y1 - 2007/2/20

N2 - We report on the disco very of a faint (MV ∼ -10.6 ± 0.2)dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends ≳1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepest CMD for a small dwarf galaxy inside a cluster environment. Using the colors of the RGB stars, we derive a metal abundance for the dwarf of [M/H] = -2,3 ± 0.3 and show that the metallicity dispersion is less than 0.6 dex at 95% confidence. We also use the galaxy's lack of AGB stars and the absence of objects brighter than Mbol ∼ -4.1 ∼ 0.2 to show that the system is old (t ≳ 10 Gyr). Finally, we derive the object's structural parameters and show that the galaxy displays no obvious evidence of tidal threshing. Since the tip of the red giant branch distance [(m - M)0 = 31.23 ± 0.17 or D = 17.6 ± 1.4 Mpc] puts the galaxy near the core of the Virgo cluster, one might expect the object to have undergone some tidal processing. Yet the chemical and morphological similarity between the dwarf and the dSph galaxies of the Local and M81 Group demonstrates that the object is indeed pristine and not the shredded remains of a much larger galaxy. We discuss the possible origins of this galaxy and suggest that it is just now falling into Virgo for the first time.

AB - We report on the disco very of a faint (MV ∼ -10.6 ± 0.2)dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends ≳1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepest CMD for a small dwarf galaxy inside a cluster environment. Using the colors of the RGB stars, we derive a metal abundance for the dwarf of [M/H] = -2,3 ± 0.3 and show that the metallicity dispersion is less than 0.6 dex at 95% confidence. We also use the galaxy's lack of AGB stars and the absence of objects brighter than Mbol ∼ -4.1 ∼ 0.2 to show that the system is old (t ≳ 10 Gyr). Finally, we derive the object's structural parameters and show that the galaxy displays no obvious evidence of tidal threshing. Since the tip of the red giant branch distance [(m - M)0 = 31.23 ± 0.17 or D = 17.6 ± 1.4 Mpc] puts the galaxy near the core of the Virgo cluster, one might expect the object to have undergone some tidal processing. Yet the chemical and morphological similarity between the dwarf and the dSph galaxies of the Local and M81 Group demonstrates that the object is indeed pristine and not the shredded remains of a much larger galaxy. We discuss the possible origins of this galaxy and suggest that it is just now falling into Virgo for the first time.

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