skip to main content

Title: H ii REGIONS WITHIN A COMPACT HIGH VELOCITY CLOUD. A NEARLY STARLESS DWARF GALAXY?

Within the SECCO survey we identified a candidate stellar counterpart to the Ultra Compact High Velocity Cloud (UCHVC) HVC274.68+74.70-123 that was suggested by Adams et al. to be a possible mini halo within the Local Group of galaxies. The spectroscopic follow-up of the brightest sources within the candidate reveals the presence of two H ii regions whose radial velocity is compatible with a physical association with the UVHVC. The available data do not allow us to give a definite answer on the nature of the newly identified system. A few alternative hypotheses are discussed. However, the most likely possibility is that we have found a new faint dwarf galaxy residing in the Virgo cluster of galaxies, which we name SECCO 1. Independently of its actual distance, SECCO 1 displays a ratio of neutral hydrogen mass to V luminosity of M{sub H} {sub I}/L{sub V}≳20, by far the largest among local dwarfs. Hence, it appears to be a nearly starless galaxy and it may be an example of the missing links between normal dwarfs and the dark mini halos that are predicted to exist in large numbers according to the currently accepted cosmological model.
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ; ;  [5] ;  [6] ;  [7] ; ;  [8] ;  [9]
  1. INAF—Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
  2. INAF—Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)
  3. Dipartimento di Fisica and Astronomia, Università degli Studi di Bologna, Viale Berti Pichat, 6/2, I-40127 Bologna (Italy)
  4. European Southern Observatory, Alonso de Cordova 3107, Vitacura Santiago (Chile)
  5. Obs. astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l’Université, F-67000 Strasbourg (France)
  6. Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)
  7. INAF—Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio (Italy)
  8. INAF—IASF, via E. Bassini 15, I-20133, Milano (Italy)
  9. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
Publication Date:
OSTI Identifier:
22364183
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 800; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CLOUDS; COSMOLOGICAL MODELS; DISTANCE; GALAXIES; GALAXY CLUSTERS; HYDROGEN; LUMINOSITY; MASS; RADIAL VELOCITY; STARS