Arp 166

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Arp 166
NGC750 - NGC751 - SDSS DR14.png
Arp 166 consists of NGC 750 (top) and NGC 751 (bottom) (SDSS)
Observation data (J2000.0 epoch)
Constellation Triangulum
Right ascension 01h 57m 32.00s [1]
Declination +33° 12′ 24.00″ [1]
Redshift 0.017529 [2]
Heliocentric radial velocity 5255 km/s [2]
Distance 225 Mly [3]
Apparent magnitude  (B)12.90 [1]
Characteristics
Type Pair of galaxies E0+E [2]
Apparent size  (V)2.5 x 1.7 [2]
Other designations
NGC 750, NGC 751

Arp 166 is a pair of interacting elliptical galaxies approximately 225 million light-years away from Earth in the constellation of Triangulum. [2] [3] The two galaxies, NGC 750 and NGC 751, are listed together as Arp 166 in the Atlas of Peculiar Galaxies (in the category Galaxies with diffuse filaments). [4]

Contents

Observational history

Arp 166 was discovered by German-born British astronomer William Herschel on September 12, 1784, but he did not resolve this close pair of galaxies, therefore he described it as a single object NGC 750. [4] [3]

Arp 166 was first seen as a double by Irish engineer and astronomer Bindon Stoney on October 11, 1850, who used Lord Rosse's 72" telescope. [4] The second galaxy from this pair, which is smaller and fainter than NGC 750, was catalogued as NGC 751. [4]

Interacting galaxies

At least 100,000,000 years have passed since the moment of the first strong tidal perturbation between these two galaxies. [5] Both galaxies are characterized by strong tidal interactions and distortions, and they are still in the process of efficient tidal interaction. [5]

The distance between the centers of this pair is 21", or 10 kpc in projection. [6] [5] Both galaxies have almost identical central radial velocities. [5] While NGC 750 exhibits nearly flat radial velocity curves, the radial velocity curves of NGC 751 are characterized by large variations of more than 100 km s−1 along the slit. [5]

A large, diffuse tidal tail extends 20 arcsec (10 kpc) to the north-east of the pair. [5]

References

  1. 1 2 3 "SIMBAD Astronomical Database" . Retrieved March 7, 2019.
  2. 1 2 3 4 5 "NASA/IPAC Extragalactic Database". ned.ipac.caltech.edu. Retrieved March 7, 2019.
  3. 1 2 3 "Focal Pointe Observatory". bf-astro.com. Retrieved March 7, 2019.
  4. 1 2 3 4 "Data for NGC 750/751". www.astronomy-mall.com. Retrieved March 7, 2019.
  5. 1 2 3 4 5 6 Madejsky, R. (1991). "Morphology and kinematics of the interacting elliptical galaxies NGC750 and NGC751 = ARP 166 - Velocity fields of tidally distorted elliptical galaxies". Astronomy and Astrophysics . 247: 348–356. Bibcode:1991A&A...247..348M.
  6. ↑ Sandage, A.; Bedke, J. (1994). The Carnegie Atlas of Galaxies. Volume I. Carnegie Institution of Washington. Bibcode:1994cag..book.....S.
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