Eridanus iv: An ultra-faint dwarf galaxy candidate discovered in the decam local volume exploration survey

W. Cerny, A. B. Pace, A. Drlica-Wagner, S. E. Koposov, A. K. Vivas, S. Mau, A. H. Riley, C. R. Bom, J. L. Carlin, Y. Choi, D. Erkal, P. S. Ferguson, D. J. James, T. S. Li, D. Martínez-Delgado, C. E. Martínez-Vázquez, R. R. Munoz, B. Mutlu-Pakdil, K. A.G. Olsen, A. PieresJ. D. Sakowska, D. J. Sand, J. D. Simon, A. Smercina, G. S. Stringfellow, E. J. Tollerud, M. Adamów, D. Hernandez-Lang, N. Kuropatkin, L. Santana-Silva, D. L. Tucker, A. Zenteno

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


We present the discovery of a candidate ultra-faint Milky-Way satellite, Eridanus IV (DELVE J0505-0931), detected in photometric data from the DECam Local Volume Exploration survey (DELVE). Eridanus IV is a faint (MV = - 4.7 ± 0.2), extended ( = - r 75+ pc 1 2 13 16 ), and elliptical (ò = 0.54 ± 0.1) system at a heliocentric distance of - 76.7+ kpc 6.1 4.0 , with a stellar population that is well described by an old, metal-poor isochrone (age of τ ∼ 13.0 Gyr and metallicity of [Fe/H] - 2.1 dex). These properties are consistent with the known population of ultra-faint Milky-Way satellite galaxies. Eridanus IV is also prominently detected using proper-motion measurements from Gaia Early Data Release 3, with a systemic proper motion of (ma cos d, md) = (+0.25 0.06, -0.10 0.05) mas yr-1 measured from its horizontal branch and red-giant-branch member stars. We find that the spatial distribution of likely member stars hints at the possibility that the system is undergoing tidal disruption.

Original languageEnglish (US)
Article numberL44
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Oct 20 2021

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Eridanus iv: An ultra-faint dwarf galaxy candidate discovered in the decam local volume exploration survey'. Together they form a unique fingerprint.

Cite this