Dwarf spiral galaxy

A dwarf spiral galaxy is the dwarf version of a spiral galaxy. Dwarf galaxies are characterized as having low luminosities, small diameters (less than 5 kpc), low surface brightnesses, and low hydrogen masses.[1] The galaxies may be considered a subclass of low-surface-brightness galaxies.

Dwarf spiral galaxies, particularly the dwarf counterparts of Sa-Sc type spiral galaxies, are quite rare. In contrast, dwarf elliptical galaxies, dwarf irregular galaxies, and the dwarf versions of Magellanic type galaxies (which may be considered transitory between spiral and irregular in terms of morphology) are very common.[1]

It is suggested that dwarf spiral galaxies can transform into dwarf elliptical galaxies, especially in dense cluster environments.[2]

NGC 5474 I FUV g2006
NGC 5474, an example of a dwarf spiral galaxy

Examples

Location

Most identified dwarf spiral galaxies are located outside clusters.[1] Strong gravitational interactions between galaxies and interactions between galaxies and intracluster gas are expected to destroy the disks of most dwarf spiral galaxies.[1][3] Nonetheless, dwarf galaxies with spiral-like structure have been identified within the Virgo Cluster and Coma Cluster.[3][4][5][6]

References

  1. ^ a b c d J. M. Schombert; R. A. Pildis; J. A. Eder; A. Oelmer, Jr. (1995). "Dwarf Spirals". Astronomical Journal. 110: 2067–2074. Bibcode:1995AJ....110.2067S. doi:10.1086/117669.
  2. ^ Ben Moore; Neal Katz; George Lake; Alan Dressler; Augustus Oemler (1 February 1996). "Galaxy harassment and the evolution of clusters of galaxies". Nature. 379 (6566): 613–616. arXiv:astro-ph/9510034. Bibcode:1996Natur.379..613M. doi:10.1038/379613a0.
  3. ^ a b A. W. Graham; H. Jerjen; R. Guzmán (2003). "Hubble Space Telescope Detection of Spiral Structure in Two Coma Cluster Dwarf Galaxies". Astronomical Journal. 126 (4): 1787–1793. arXiv:astro-ph/0308241. Bibcode:2003AJ....126.1787G. doi:10.1086/378166.
  4. ^ H. Jerjen; A. Kalnajs; B. Binggeli (2000). "IC3328: A "dwarf elliptical galaxy" with spiral structure". Astronomy and Astrophysics. 358: 845–849. arXiv:astro-ph/0004248. Bibcode:2000A&A...358..845J.
  5. ^ F. D. Barazza; B. Binggeli; H. Jerjen (2002). "More evidence for hidden spiral and bar features in bright early-type dwarf galaxies". Astronomy and Astrophysics. 391 (3): 823–831. arXiv:astro-ph/0206275. Bibcode:2002A&A...391..823B. doi:10.1051/0004-6361:20020875.
  6. ^ T. Lisker; E. K. Grebel; B. Binggeli (2006). "Virgo Cluster Early-Type Dwarf Galaxies with the Sloan Digital Sky Survey. I. On the Possible Disk Nature of Bright Early-Type Dwarfs". Astronomical Journal. 132 (2): 497–513. arXiv:astro-ph/0604216. Bibcode:2006AJ....132..497L. doi:10.1086/505045.
DS

DS may refer to:

Diodorusii Siculus (D.S. or DS), a first-century BCE Greek historian

D/s, short for dominance and submission

Dunajská Streda, a town in Slovakia using the car registration DS

Enchiridion symbolorum, definitionum et declarationum de rebus fidei et morum, book of Catholic dogma, abbreviated DS for "Denzinger-Schönmetzer"

DS, linguistic glossing abbreviation for "different subject" in switch-reference

Dwarf elliptical galaxy

Dwarf elliptical galaxies, or dEs, are elliptical galaxies that are smaller than ordinary elliptical galaxies. They are quite common in galaxy groups and clusters, and are usually companions to other galaxies.

Dwarf galaxy

A dwarf galaxy is a small galaxy composed of about 100 million up to several billion stars, a small number compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.

IC 2574

IC 2574, also known as Coddington's Nebula is a dwarf spiral galaxy discovered by American astronomer Edwin Foster Coddington in 1898. Located in Ursa Major, a constellation in the northern sky, it is an outlying member of the M81 Group. It is believed that 90% of its mass is in the form of dark matter.

Large Magellanic Cloud

The Large Magellanic Cloud (LMC) is a satellite galaxy of the Milky Way. At a distance of about 50 kiloparsecs (≈163,000 light-years), the LMC is the second- or third-closest galaxy to the Milky Way, after the Sagittarius Dwarf Spheroidal (~16 kpc) and the possible dwarf irregular galaxy known as the Canis Major Overdensity. Based on readily visible stars and a mass of approximately 10 billion solar masses, the diameter of the LMC is about 14,000 light-years (4.3 kpc), making it roughly one one-hundredth as massive as the Milky Way. This makes the LMC the fourth-largest galaxy in the Local Group, after the Andromeda Galaxy (M31), the Milky Way, and the Triangulum Galaxy (M33).

The LMC is classified as a Magellanic spiral. It contains a stellar bar that is geometrically off-center, suggesting that it was a barred dwarf spiral galaxy before its spiral arms were disrupted, likely by tidal interactions from the Small Magellanic Cloud (SMC), and the Milky Way's gravity.With a declination of about -70°, the LMC is visible as a faint "cloud" only in the southern celestial hemisphere and from latitudes south of 20° N, straddling the border between the constellations of Dorado and Mensa, and appears longer than 20 times the Moon's diameter (about 10° across) from dark sites away from light pollution.The Milky Way and the LMC are expected to collide in approximately 2.4 billion years.

NGC 247

NGC 247 is an intermediate spiral galaxy (although it is sometimes classified as a dwarf spiral galaxy) about 11.1 Mly away in the constellation Cetus. This distance was confirmed in late February 2011. Previous measurements showed that the galaxy was about 12.2 Mly away, but this was proved to be wrong. NGC 247 is a member of the Sculptor Group.

NGC 247 is marred by an unusually large void on one side of its spiral disk. This void contains some older, redder stars but no younger, bluer stars.

NGC 5474

NGC 5474 is a peculiar dwarf galaxy in the constellation Ursa Major. It is one of several companion galaxies of the Pinwheel Galaxy (M101), a grand-design spiral galaxy.

Among the Pinwheel Galaxy's companions, this galaxy is the closest to the Pinwheel Galaxy itself. The gravitational interaction between NGC 5474 and the Pinwheel Galaxy has strongly distorted the former. As a result, the disk is offset relative to the nucleus. The star formation in this galaxy (as traced by hydrogen spectral line emission) is also offset from the nucleus. NGC 5474 shows some signs of a spiral structure. As a result, this galaxy is often classified as a dwarf spiral galaxy, a relatively rare group of dwarf galaxies.

NGC 5949

NGC 5949 is a dwarf spiral galaxy located about 44 million light years away in the constellation of Draco.

NGC 6503

NGC 6503 is a field dwarf spiral galaxy located at the edge of a region of space called the Local Void. The dwarf galaxy spans 30,000 light-years and lies approximately 17 million light-years away in the constellation of Draco (the Dragon). The spiral galaxy is especially colorful where bright red regions of gas can be seen scattered through its spiral arms. Bright blue regions contain stars that are forming. Dark brown dust areas are in the galaxy's arms and center.

Morphology
Structure
Active nuclei
Energetic galaxies
Low activity
Interaction
Lists
See also

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