Unbarred spiral galaxy

An unbarred spiral galaxy[1][2] is a type of spiral galaxy without a central bar, or one that is not a barred spiral galaxy. It is designated with an SA in the galaxy morphological classification scheme.

The Sombrero Galaxy is an unbarred spiral galaxy.

Barless spiral galaxies are one of three general types of spiral galaxies under the de Vaucouleurs system classification system, the other two being intermediate spiral galaxy and barred spiral galaxy. Under the Hubble tuning fork, it is one of two general types of spiral galaxy, the other being barred spirals.

Messier51 sRGB
The Whirlpool Galaxy and its companion satellite. The Whirlpool is an unbarred spiral galaxy

Grades

Galaxy morphology
Under the de Vaucouleurs classification system, SA-galaxies are one of three types of spiral galaxy
Example Type Image Information Notes
SA0- SA0- is a type of lenticular galaxy
SA0 SA0 is a type of lenticular galaxy
SA0+ SA0+ is a type of lenticular galaxy
NGC 3593 SA0/a Ngc3593 SA0/a can also be considered a type of unbarred lenticular galaxy NGC 3593 is an "SA(s)0/a"
NGC 3169 SAa NGC 3169 NGC 3169 is an "SA(s)a pec"
Messier 81 SAab Messier 81 HST M81 is an "SA(s)ab"
Messier 88 SAb M88HunterWilson M88 is an "SA(rs)b"
NGC 3949 SAbc NGC 3949 NGC 3949 is an "SA(s)bc"
NGC 4414 SAc NGC 4414 (NASA-med) NGC 4414 is an "SA(rs)c"
Triangulum Galaxy SAcd M33 Triangulum is an "SA(s)cd"
NGC 300 SAd Composite Image of NGC 300 NGC 300 is an "SA(s)d"
NGC 45 SAdm NGC 45 GALEX WikiSky SAdm can also be considered a type of unbarred Magellanic spiral NGC 45 is an "SA(s)dm"
NGC 4395 SAm Ngc4395 SAm is a type of Magellanic spiral (Sm) NGC 4395 is an "SA(s)m"

References

  1. ^ Astronomical Journal, "Near-infrared surface photometry and morphology in virgo cluster spiral galaxy nuclear regions", Bernard J. Rauscher, April 1995, Bibcode1995AJ....109.1608R, doi:10.1086/117389
  2. ^ Astronomy Pictures, "M99" (accessed 18 April 2010)
Intermediate spiral galaxy

An intermediate spiral galaxy is a galaxy that is in between the classifications of a barred spiral galaxy and an unbarred spiral galaxy. It is designated as SAB in the galaxy morphological classification system devised by Gerard de Vaucouleurs. Subtypes are labeled as SAB0, SABa, SABb, or SABc, following a sequence analogous to the Hubble sequence for barred and unbarred spirals. The subtype (0, a, b, or c) is based on the relative prominence of the central bulge and how tightly wound the spiral arms are.

NGC 177

NGC 177 is an unbarred spiral galaxy with a distinct ring structure, located around 200 million light-years away in the constellation Cetus. It was discovered in 1886 by Frank Muller.

NGC 2541

NGC 2541 is an unbarred spiral galaxy located about 40 million light-years away. It is in the NGC 2841 group of galaxies with NGC 2500, NGC 2537, and NGC 2552.

NGC 2775

NGC 2775 (also known as Caldwell 48) is an unbarred spiral galaxy with a prominent ring structure in the constellation Cancer. This galaxy has a bulge and multiple spiral arms, on which few HII regions can be detected, implying recent star formation. It was discovered by William Herschel in 1783.

NGC 2775 is the most prominent galaxy in a small galaxy group known as NGC 2775 group, part of the Virgo Supercluster, along with the Local Group. Other members of the NGC 2775 group include NGC 2777 and UGC 4781.SN1993z is the only supernova known to have occurred in NGC 2775 and was a Type Ia on Sept. 23rd that year at a magnitude of 13.9. By the 25th, spectra that was obtained showed that it had peaked four weeks earlier.

NGC 296

NGC 296 is a low surface brightness unbarred spiral galaxy in the constellation of Pisces. The designation NGC 295 is sometimes mistakenly used for NGC 296.

NGC 2997

NGC 2997 is a face-on unbarred spiral galaxy about 25 million light-years away in the constellation Antlia. It is the brightest galaxy of the NGC 2997 group of galaxies.

NGC 2997 is particularly notable for a nucleus surrounded by a chain of hot giant clouds of ionized hydrogen. It is featured on the cover of the first edition of Galactic Dynamics by James Binney and Scott Tremaine.

NGC 4420

NGC 4420 is an unbarred spiral galaxy located 77 million light-years away in the constellation Virgo.

NGC 4580

NGC 4580 is an unbarred spiral galaxy located about 70 million light-years away in the constellation Virgo. NGC 4580 is also classified as a LINER galaxy. It was discovered by astronomer William Herschel on February 2, 1786 and is a member of the Virgo Cluster.

NGC 4622

NGC 4622 is a face-on unbarred spiral galaxy with a very prominent ring structure located in the constellation Centaurus. The galaxy is a member of the Centaurus Cluster.

NGC 5144

NGC 5144 is an unbarred spiral galaxy.

NGC 5676

NGC 5676 is an unbarred spiral galaxy in the constellation Boötes.

NGC 6753

NGC 6753 is an unbarred spiral galaxy, seen almost exactly face-on, located in the constellation Pavo.

NGC 6925

NGC 6925 is an unbarred spiral galaxy in the constellation Microscopium of apparent magnitude 11.3. It is lens-shaped, as it lies almost edge on to observers on Earth. It lies 3.7 degrees west-northwest of Alpha Microscopii.SN 2011ei, a Type II supernova in NGC 6925, was discovered by Stu Parker in New Zealand in July 2011.

NGC 7083

NGC 7083 is a unbarred spiral galaxy located about 134 million light-years away in the constellation of Indus. It is also classified as a flocculent spiral galaxy. NGC 7083 was discovered by astronomer James Dunlop on August 28, 1826.

NGC 772

NGC 772 (also known as Arp 78) is an unbarred spiral galaxy approximately 130 million light-years away in the constellation Aries.

NGC 7840

NGC 7840 is an unbarred spiral galaxy in the constellation Pisces.

It is the last numerical entry in the New General Catalogue.

NGC 908

NGC 908 is an unbarred spiral galaxy in the constellation Cetus. It is at a distance of 60 million light years away from Earth. NGC 908 has vigorous star formation and is a starburst galaxy. The galaxy has three-arm spiral pattern, with two arms with peculiar morphology. The central bulge of the galaxy is bright. Cluster of young stars and star forming knots can be seen in the arms. Starburst activity and the peculiar morphology of the galaxy indicated it has a close encounter with another galaxy, although none is visible now. NGC 908 was discovered in 1786 by William Herschel. Two supernovae have been observed in NGC 908, SN 1994ai (Ic type, mag. 17) and SN 2006ce (Ia type, mag. 12.4). It is the main galaxy in the NGC 908 group, which also includes NGC 899, NGC 907 and IC 223.

NGC 92

NGC 92 is a highly warped interacting unbarred spiral galaxy in Robert's Quartet; it is interacting with three neighbouring galaxies NGC 87, NGC 88 and NGC 89.

Unbarred lenticular galaxy

An unbarred lenticular galaxy is a lenticular version of an unbarred spiral galaxy. They have the Hubble type of SA0.

An example of this is the Galaxy AM 0644-741. For other examples see Category:Unbarred lenticular galaxies.

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

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