HST obs. & Gaia data of Hercules dwarf gal. Virtual Observatory Resource

Authors
  1. Mutlu-Pakdil B.
  2. Sand D.J.
  3. Crnojevic D.
  4. Olszewski E.W.,Zaritsky D.
  5. Strader J.
  6. Collins M.L.
  7. Seth A.C.
  8. Willman B.
  9. Published by
    CDS
Abstract

The ultrafaint dwarf galaxy Hercules has an extremely elongated morphology with both photometric overdensities and kinematic members at large radii, suggesting that it may be tidally disrupting due to a previous close encounter with the Milky Way. To explain its observational peculiarities, we present a deep Hubble Space Telescope (HST) imaging study of Hercules and its surrounding regions and investigate its tidal history through a careful search for a distance gradient along its stretched body. Our off-center HST data clearly resolve a main sequence, showing that the stellar extension seen along the major axis of Hercules is genuine, not a clump of background galaxies. Utilizing Gaia DR2 data, we clean the region around the Hercules of field contamination, and find four new plausible member stars, all of which are located on the outskirts of the dwarf galaxy. We update the distance to Hercules, and find 130.6R+/-6.1kpc (m-M=20.58+/-0.10) for the main body, which is consistent with earlier estimates in the literature. While we find no conclusive evidence for a distance gradient, our work demonstrates that constraining a distance gradient in such a faint system is not trivial, and the possible thickness of the dwarf along the line of sight and field contamination make it harder to make decisive conclusions even with these high-precision data. Future studies coupled with tailored theoretical models are needed to understand the true nature of Hercules and of tidal distortion observables in ultrafaint galaxies in general.

Keywords
  1. galaxies
  2. photometry
  3. hst-photometry
  4. proper-motions
  5. extinction
  6. infrared-photometry
  7. visible-astronomy
Bibliographic source Bibcode
2020ApJ...902..106M
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/902/106
IVOA Identifier IVOID
ivo://CDS.VizieR/J/ApJ/902/106
Document Object Identifer DOI
doi:10.26093/cds/vizier.19020106

Access

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http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/902/106
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/902/106
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/902/106
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http://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/902/106/table2?
https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/902/106/table2?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/902/106/table2?
IVOA Cone Search SCS
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http://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/902/106/table4?
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http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/902/106/table4?
IVOA Cone Search SCS
For use with a cone search client (e.g., TOPCAT).
http://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/902/106/table5?
https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/902/106/table5?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/902/106/table5?

History

2022-05-10T12:45:21Z
Resource record created
2022-05-10T12:45:21Z
Created
2022-10-26T11:03:00Z
Updated

Contact

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CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
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cds-question@unistra.fr