NGC 3998

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NGC 3998
NGC3998 - SDSS DR14.jpg
SDSS image of NGC 3998
Observation data (J2000 epoch)
Constellation Ursa Major
Right ascension 11h 57m 56.1333s [1]
Declination +55° 27′ 12.922″ [1]
Redshift 0.00350 [1]
Helio radial velocity 1048 ± 5 km/s [1]
Distance 45  Mly (13.7  Mpc) [2]
Apparent magnitude  (V)12.10 [3]
Apparent magnitude  (B)11.64 [4]
Absolute magnitude  (V)2.7′ × 2.3′ [5]
Characteristics
Type SA00(r): [1]
Other designations
UGC 6946, MCG +09-20-046, PGC 37642 [1]

NGC 3998 is a lenticular galaxy located in the constellation Ursa Major. It was discovered on April 14, 1789, by the astronomer William Herschel. [5] At a distance of 45 million light-years (13.7 megaparsecs), [2] it is located relatively nearby, making it a well-studied object. [6]

Contents

In Gérard de Vaucouleurs' atlas of galaxy morphological types, NGC 3998 has a classification of SA00(r):, meaning it is unbarred and has an internal ring. [5] It is classified as a LINER-type galaxy. [6] As an early-type galaxy, NGC 3998's stars are relatively old and reddish in color, but its nuclear region may still have signs of star formation with stars less than 10 million years old. [6] The galaxy's shape is very round, and also oblate. [2]

Structure

NGC 3998 contains an active galactic nucleus, or AGN. These are supermassive black holes that are surrounded by accretion disks that emit large amounts of energy across the electromagnetic spectrum. The supermassive black hole has been modeled to be about 8.1+2.0
−1.9×108  M☉ [2] The AGN's power is relatively low, and like most other low-power radio galaxies, most of its emission is concentrated near its core. However, it also has some S-shaped lobes of emission, which are quite young and active, at only a few tens of millions of years old. [7]

NGC 3998 has a small disk of ionized Hα radiation that is about 100 parsecs wide, along with a larger, warped disk of neutral hydrogen. It is thought that the gas disk has just started to align with the stellar distribution, which would also explain the warped shape of the radio emission. [6] [7]

Related Research Articles

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<span class="mw-page-title-main">NGC 1672</span> Barred spiral galaxy in the constellation Dorado

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<span class="mw-page-title-main">NGC 612</span> Spiral galaxy in the constellation Sculptor

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<span class="mw-page-title-main">NGC 541</span> Lenticular galaxy in the constellation Cetus

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<span class="mw-page-title-main">NGC 1386</span> Spiral seyfert galaxy in the constellation Eridanus

NGC 1386 is a spiral galaxy located in the constellation Eridanus. It is located at a distance of circa 53 million light years from Earth, which, given its apparent dimensions, means that NGC 1386 is about 50,000 light years across. It is a Seyfert galaxy, the only one in Fornax Cluster.

<span class="mw-page-title-main">NGC 3665</span> Lenticular galaxy in the constellation Ursa Major

NGC 3665 is a lenticular galaxy located in the constellation Ursa Major. It is located at a distance of circa 85 million light-years from Earth, which, given its apparent dimensions, means that NGC 3665 is about 85,000 light years across. It was discovered by William Herschel on March 23, 1789.

<span class="mw-page-title-main">NGC 4278</span> Elliptical galaxy in the constellation Coma Berenices

NGC 4278 is an elliptical galaxy located in the constellation Coma Berenices. It is located at a distance of circa 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4278 is about 65,000 light years across. It was discovered by William Herschel on March 13, 1785. NGC 4278 is part of the Herschel 400 Catalogue and can be found about one and 3/4 of a degree northwest of Gamma Comae Berenices even with a small telescope.

<span class="mw-page-title-main">NGC 4093</span> Elliptical galaxy in the constellation Coma Berenices

NGC 4093 is an elliptical galaxy located 340 million light-years away in the constellation Coma Berenices. The galaxy was discovered by astronomer Heinrich d'Arrest on May 4, 1864. NGC 4093 is a member of the NGC 4065 Group and is a radio galaxy with a two sided jet.

<span class="mw-page-title-main">NGC 5728</span> Spiral galaxy in the constellation Libra

NGC 5728 is an active barred spiral galaxy located 146 million light years away in the southern constellation of Libra. It was discovered on May 7, 1787 by William Herschel. The designation comes from the New General Catalogue of J. L. E. Dreyer, published in 1888. It has an apparent visual magnitude of 13.40 and spans an angle of 3.4 arcminutes. The galaxy shows a red shift of 0.00935 and has a heliocentric radial velocity of 2,803 km/s. It has an estimated mass of 72 billion times the mass of the Sun and stretches around 30 kpc across.

<span class="mw-page-title-main">NGC 7679</span> Galaxy in the constellation Pisces

NGC 7679 is a lenticular galaxy with a peculiar morphology in the constellation Pisces. It is located at a distance of circa 200 million light years from Earth, which, given its apparent dimensions, means that NGC 7679 is about 60,000 light years across. It was discovered by Heinrich d'Arrest on September 23, 1864. The total infrared luminosity is 1011.05 L☉, and thus it is categorised as a luminous infrared galaxy. NGC 7679 is both a starburst galaxy and a Seyfert galaxy.

<span class="mw-page-title-main">NGC 4324</span> Lenticular galaxy in the constellation of Virgo

NGC 4324 is a lenticular galaxy located about 85 million light-years away in the constellation Virgo. It was discovered by astronomer Heinrich d'Arrest on March 4, 1862. NGC 4324 has a stellar mass of 5.62 × 1010M☉, and a baryonic mass of 5.88 × 1010M☉. The galaxy's total mass is around 5.25 × 1011M☉. NGC 4324 is notable for having a ring of star formation surrounding its nucleus. It was considered a member of the Virgo II Groups until 1999, when its distance was recalculated and it was placed in the Virgo W Group.

<span class="mw-page-title-main">NGC 2617</span> Spiral galaxy in the constellation Hydra

NGC 2617 is a Seyfert galaxy in the equatorial constellation of Hydra. It was discovered on February 12, 1885, by French astronomer Édouard Stephan. In 1888, Danish astronomer J. L. E. Dreyer described it as "extremely faint, very small, 2 very faint stars involved". It is located at an estimated distance of 202 million light years. In the infrared, the galaxy has an angular size of 0.693 by 0.652 arcminutes.

References

  1. 1 2 3 4 5 6 "Results for object NGC 3998 (NGC 3998)". NASA/IPAC Extragalactic Database. California Institute of Technology. Retrieved 2021-04-25.
  2. 1 2 3 4 Walsh, Jonelle L.; Van Den Bosch, Remco C. E.; Barth, Aaron J.; Sarzi, Marc (2012). "A Stellar Dynamical Mass Measurement of the Black Hole in NGC 3998 from Keck Adaptive Optics Observations". The Astrophysical Journal. 753 (1): 79. arXiv: 1205.0816 . Bibcode:2012ApJ...753...79W. doi:10.1088/0004-637X/753/1/79. S2CID   16506695.
  3. ↑ Véron-Cetty, M.-P.; Véron, P. (2010). "A catalogue of quasars and active nuclei". Astronomy and Astrophysics (13th ed.). 518: A10. Bibcode:2010A&A...518A..10V. doi: 10.1051/0004-6361/201014188 .
  4. ↑ "NGC 3998". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2021-04-25.
  5. 1 2 3 Seligman, Courtney. "New General Catalogue objects: NGC 3950 - 3999". cseligman.com. Retrieved 2021-04-25.
  6. 1 2 3 4 Frank, Bradley S.; Morganti, Raffaella; Oosterloo, Tom; Nyland, Kristina; Serra, Paolo (2016). "A rare example of low surface-brightness radio lobes in a gas-rich early-type galaxy: The story of NGC 3998". Astronomy & Astrophysics. 592: A94. arXiv: 1605.03873 . Bibcode:2016A&A...592A..94F. doi:10.1051/0004-6361/201628282. S2CID   73593876.
  7. 1 2 Sridhar, Sarrvesh S.; Morganti, Raffaella; Nyland, Kristina; Frank, Bradley S.; Harwood, Jeremy; Oosterloo, Tom (2020). "LOFAR view of NGC 3998, a sputtering AGN". Astronomy & Astrophysics. 634: A108. arXiv: 1912.04812 . Bibcode:2020A&A...634A.108S. doi:10.1051/0004-6361/201936796. S2CID   209140612.
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