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| Local Volume | |
|---|---|
| Name | Local Volume |
| Caption | Nearby galaxies within ~11 Mpc |
| Type | Volume of space |
| Distance | ~11 Mpc (≈35 million ly) |
| Major components | Milky Way, Andromeda Galaxy, Triangulum Galaxy, M81 Group, Centaurus A Group |
Local Volume is the region of extragalactic space encompassing galaxies and galaxy groups within roughly 11 megaparsecs of the Milky Way. It serves as the most accessible volume for detailed studies of galactic structure, stellar populations, and intergalactic environment, linking observations from the Hubble Space Telescope, Very Large Telescope, and ALMA to cosmological inferences from the Planck (spacecraft), Wilkinson Microwave Anisotropy Probe, and Sloan Digital Sky Survey.
The Local Volume is defined observationally by distance limits (~11 Mpc) and includes members cataloged by surveys such as the Local Volume Legacy, the Catalog of Neighboring Galaxies and the Extragalactic Distance Database. It overlaps conceptually with the Local Group, the Local Sheet, and the Local Supercluster centered on the Virgo Cluster. Important nearby associations inside the volume include the M81 Group, the Centaurus A/M83 Group, the Sculptor Group, and isolated dwarfs like IC 10, NGC 6822, and NGC 3109.
The identification of a nearby concentration of galaxies evolved from early work by Edwin Hubble, who resolved stellar populations in nearby systems such as the Andromeda Galaxy, to later systematic catalogs by Walter Baade, Harlow Shapley, and Gerard de Vaucouleurs. Distance measurement improvements via the Cepheid variable period-luminosity relation refined by Henrietta Leavitt and techniques using the Tip of the Red Giant Branch allowed mapping of the Local Volume. Modern surveys by Frederic Chaffee, J. J. Salzer, R. Brent Tully, and teams associated with the Hubble Key Project formalized the region now termed the Local Volume.
The Local Volume contains a diverse population: massive spirals like the Milky Way and Andromeda Galaxy, intermediate systems such as M81 and M82, lenticulars and ellipticals including NGC 5128 (Centaurus A), and a rich dwarf galaxy population exemplified by Sextans A, Sextans B, Leo A, DDO 210, and UGC 4879. Satellite systems include the Large Magellanic Cloud, Small Magellanic Cloud, M33 (the Triangulum Galaxy), and dwarf spheroidals such as Sculptor Dwarf, Fornax Dwarf, Draco Dwarf, and Ursa Minor Dwarf. Starburst galaxies like NGC 1569 and NGC 253 contribute to the Local Volume's range of morphologies cataloged in projects like the Two Micron All Sky Survey and the Galaxy Evolution Explorer.
On scales within the volume, galaxies trace structures such as the Local Sheet, the Tully Void, and filaments connected to the Virgo Supercluster. Dynamical analyses use rotation curves of spirals (e.g., NGC 300, NGC 2403), velocity dispersions of dwarfs (e.g., Carina Dwarf, Sextans Dwarf), and proper motions from Gaia (spacecraft) to infer mass distributions including dark matter halos characterized by Navarro–Frenk–White profile fits. Interactions and mergers are evident in features like tidal streams around the Andromeda Galaxy and the Sagittarius Dwarf Elliptical Galaxy disruption of the Milky Way, and in the starburst triggered in M82 by interaction with M81.
Spatially resolved studies probe star formation histories via color–magnitude diagrams from Hubble Space Telescope imaging and spectroscopic metallicity measures from instruments on the Keck Observatory and Gemini Observatory. Metallicity gradients and stellar population variations in systems like NGC 300 and IC 1613 inform models of chemical evolution developed by groups associated with Max Planck Institute for Astronomy and Space Telescope Science Institute. Feedback processes from supernovae in dwarfs such as IC 10 and NGC 2366 illustrate mass-loss and quenching mechanisms also studied in the context of cosmological simulations by teams around Illustris and EAGLE.
Distances inside the Local Volume are measured using Cepheid variables, the Tip of the Red Giant Branch, Surface Brightness Fluctuations, and Planetary Nebula Luminosity Function calibrations refined by the Hubble Key Project and the Carnegie Hubble Program. Wide-area and targeted surveys include the Sloan Digital Sky Survey, Pan-STARRS, the ALFALFA survey, the Local Volume HI Survey, and the HST Advanced Camera for Surveys Nearby Galaxy Survey Treasury (ANGST). Radio observations from Very Large Array, molecular studies with ALMA, and infrared imaging from Spitzer Space Telescope and Wide-field Infrared Survey Explorer complement optical data; proper motion and parallax constraints use Gaia releases.
The Local Volume provides a testbed for ΛCDM predictions about galaxy abundance, the "missing satellites" problem highlighted by comparisons between observed dwarfs (e.g., Leo I, Leo II) and subhalo counts from simulations by Vera C. Rubin Observatory collaborators. Environmental effects such as ram-pressure stripping in groups like M81 Group, tidal stirring near Andromeda Galaxy, and cosmic web influences from filaments connecting to the Virgo Cluster inform theories pursued by researchers at Cambridge University, Princeton University, and Carnegie Observatories. Studies of star formation suppression, morphological transformation, and local large-scale flows contribute constraints used alongside cosmic microwave background results from Planck (spacecraft) and WMAP.
Category:Galaxy groups