From globular clusters to tidal dwarfs

Structure formation in the tidal tails of merging galaxies

Karen A. Knierman, Sarah C. Gallagher, Jane Camilla Charlton, Sally D. Hunsberger, Bradley Whitmore, Arunav Kundu, J. E. Hibbard, Dennis Zaritsky

Research output: Contribution to journalArticle

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Abstract

Using V and I images obtained with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope, we investigate compact stellar structures within tidal tails. Six regions of tidal debris in the four classic "Toomre sequence" mergers: NGC 4038/39 ("Antennae"), NGC 3256, NGC 3921, and NGC 7252 ("Atoms for Peace") have been studied in order to explore how the star formation depends on the local and global physical conditions. These mergers sample a range of stages in the evolutionary sequence and tails with and without embedded tidal dwarf galaxies. The six tails are found to contain a variety of stellar structures, with sizes ranging from those of globular clusters up to those of dwarf galaxies. From V and I WFPC2 images, we measure the luminosities and colors of the star clusters. NGC 3256 is found to have a large population of blue clusters (0.2 ≲ V-I ≲ 0.9), particularly in its western tail, similar to those found in the inner region of the merger. In contrast, NGC 4038/39 has no clusters in the observed region of the tail, only less luminous point sources likely to be individual stars. NGC 3921 and NGC 7252 have small populations of clusters along their tails. A significant cluster population is clearly associated with the prominent tidal dwarf candidates in the eastern and western tails of NGC 7252. The cluster-rich western tail of NGC 3256 is not distinguished from the others by its dynamical age or by its total H I mass. However, the mergers that have few clusters in the tail all have tidal dwarf galaxies, while NGC 3256 does not have prominent tidal dwarfs. We speculate that star formation in tidal tails may manifest itself either in small structures like clusters along the tail or in large structures such as dwarf galaxies, but not in both. Also, NGC 3256 has the highest star formation rate of the four mergers studied, which may contribute to the high number of star clusters in its tidal tails.

Original languageEnglish (US)
Pages (from-to)1227-1244
Number of pages18
JournalAstronomical Journal
Volume126
Issue number3 1773
DOIs
StatePublished - Sep 1 2003

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globular clusters
merger
galaxies
dwarf galaxies
stellar structure
star clusters
star formation
cameras
point source
antenna
star formation rate
Hubble Space Telescope
debris
point sources
antennas
luminosity
color
stars
atoms

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Knierman, K. A., Gallagher, S. C., Charlton, J. C., Hunsberger, S. D., Whitmore, B., Kundu, A., ... Zaritsky, D. (2003). From globular clusters to tidal dwarfs: Structure formation in the tidal tails of merging galaxies. Astronomical Journal, 126(3 1773), 1227-1244. https://doi.org/10.1086/377481
Knierman, Karen A. ; Gallagher, Sarah C. ; Charlton, Jane Camilla ; Hunsberger, Sally D. ; Whitmore, Bradley ; Kundu, Arunav ; Hibbard, J. E. ; Zaritsky, Dennis. / From globular clusters to tidal dwarfs : Structure formation in the tidal tails of merging galaxies. In: Astronomical Journal. 2003 ; Vol. 126, No. 3 1773. pp. 1227-1244.
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abstract = "Using V and I images obtained with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope, we investigate compact stellar structures within tidal tails. Six regions of tidal debris in the four classic {"}Toomre sequence{"} mergers: NGC 4038/39 ({"}Antennae{"}), NGC 3256, NGC 3921, and NGC 7252 ({"}Atoms for Peace{"}) have been studied in order to explore how the star formation depends on the local and global physical conditions. These mergers sample a range of stages in the evolutionary sequence and tails with and without embedded tidal dwarf galaxies. The six tails are found to contain a variety of stellar structures, with sizes ranging from those of globular clusters up to those of dwarf galaxies. From V and I WFPC2 images, we measure the luminosities and colors of the star clusters. NGC 3256 is found to have a large population of blue clusters (0.2 ≲ V-I ≲ 0.9), particularly in its western tail, similar to those found in the inner region of the merger. In contrast, NGC 4038/39 has no clusters in the observed region of the tail, only less luminous point sources likely to be individual stars. NGC 3921 and NGC 7252 have small populations of clusters along their tails. A significant cluster population is clearly associated with the prominent tidal dwarf candidates in the eastern and western tails of NGC 7252. The cluster-rich western tail of NGC 3256 is not distinguished from the others by its dynamical age or by its total H I mass. However, the mergers that have few clusters in the tail all have tidal dwarf galaxies, while NGC 3256 does not have prominent tidal dwarfs. We speculate that star formation in tidal tails may manifest itself either in small structures like clusters along the tail or in large structures such as dwarf galaxies, but not in both. Also, NGC 3256 has the highest star formation rate of the four mergers studied, which may contribute to the high number of star clusters in its tidal tails.",
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Knierman, KA, Gallagher, SC, Charlton, JC, Hunsberger, SD, Whitmore, B, Kundu, A, Hibbard, JE & Zaritsky, D 2003, 'From globular clusters to tidal dwarfs: Structure formation in the tidal tails of merging galaxies', Astronomical Journal, vol. 126, no. 3 1773, pp. 1227-1244. https://doi.org/10.1086/377481

From globular clusters to tidal dwarfs : Structure formation in the tidal tails of merging galaxies. / Knierman, Karen A.; Gallagher, Sarah C.; Charlton, Jane Camilla; Hunsberger, Sally D.; Whitmore, Bradley; Kundu, Arunav; Hibbard, J. E.; Zaritsky, Dennis.

In: Astronomical Journal, Vol. 126, No. 3 1773, 01.09.2003, p. 1227-1244.

Research output: Contribution to journalArticle

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T2 - Structure formation in the tidal tails of merging galaxies

AU - Knierman, Karen A.

AU - Gallagher, Sarah C.

AU - Charlton, Jane Camilla

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AU - Whitmore, Bradley

AU - Kundu, Arunav

AU - Hibbard, J. E.

AU - Zaritsky, Dennis

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