NGC 3516 is a

barred lenticular galaxy A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes. It contains a large-scale disc but does not have large-scale spiral arms. ...

in the constellation of

Ursa Major Ursa Major, also known as the Great Bear, is a constellation in the Northern Sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear", referring to and contrasting it with nearby Ursa M ...

. NGC 3516 is located about 150 million

light year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s away from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

, which means, given its apparent dimensions, that NGC 3516 is approximately 100,000 light years across. It was discovered by

William Herschel Frederick William Herschel ( ; ; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover ...

on April 3, 1785.

Characteristics

In 1943, this galaxy was one of six

nebulae A nebula (; or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the Pillars of Creation in th ...

listed by American astronomer

Carl Keenan Seyfert Carl Keenan Seyfert (February 11, 1911 – June 13, 1960) was an American astronomer. He is best known for his 1943 research paper on high-excitation line emission from the centers of some spiral galaxies, which are named Seyfert galaxies after h ...

that showed broad

emission line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...

s in their nuclei. Members of this class of objects became known as

Seyfert galaxies Seyfert galaxies are one of the two largest groups of active galactic nucleus, active galaxies, along with quasar host galaxies. They have quasar-like Active galactic nucleus, nuclei (very luminous sources of electromagnetic radiation that are o ...

, and they were noted to have a higher than normal surface brightness in their nuclei. NGC 3516 is believed to host a

supermassive black hole A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (). Black holes are a class of astronomical ...

whose mass is estimated to be based on broad emission-line

reverberation mapping Reverberation mapping (or Echo mapping) is an astrophysical technique for measuring the structure of the broad-line region (BLR) around a supermassive black hole at the center of an active galaxy, and thus estimating the hole's mass. It is c ...

or as measured based on

velocity dispersion In astronomy, the velocity dispersion (''σ'') is the statistical dispersion of velocities about the mean velocity for a group of astronomical objects, such as an open cluster, globular cluster, galaxy, galaxy cluster, or supercluster. By measu ...

. Due to its high brightness in both UV and X-rays, and its prominent and clear

active galactic nucleus An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such e ...

absorption features, it has been an ideal laboratory for studying the AGN warm-absorber outflows with high-resolution

spectroscopy Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectro ...

. Over the past few decades, there have been many UV and X-ray case studies of the ionized outflows in NGC 3516. NGC 3516 has been a remarkably variable AGN, showing changes in both the intrinsic continuum and the intrinsic absorption by the ionized outflows. In 2014, the broad lines almost disappeared, probably becoming obstructed, and thus the galaxy has been identified as a changing-look AGN, meaning it changed spectra between type 1 and type 2 AGN. The galaxy has been found to emit

radiowaves Radio waves (formerly called Hertzian waves) are a type of electromagnetic radiation with the lowest frequencies and the longest wavelengths in the electromagnetic spectrum, typically with frequencies below 300 gigahertz (GHz) and wavelengths g ...

, with the source extending towards the north for about 0.65 arcseconds. That structure is a bit curved and probably is related to the gaseous outflow. A spiral dust feature measuring 3 arcseconds in diameter is visible north of the nucleus. A blue filamentary feature is visible northeast of the nucleus and another blue feature is visible 1.5 arcseconds southwest of the nucleus.

Nearby galaxies

NGC 3516 is a relatively isolated galaxy. Near galaxies include NGC 3147 with its group that

NGC 3155 NGC may refer to: Companies * NGC Corporation, the name of US electric company Dynegy, Inc. from 1995 to 1998 * National Gas Company of Trinidad and Tobago, a state-owned natural gas company in Trinidad and Tobago * National Grid plc, a former nam ...

, UGC 5570, UGC 5686, and UGC 5689, NGC 3183, NGC 3348, and NGC 3364. Garcia identified NGC 3516 as a member of group that also includes the galaxies NGC 3348, and NGC 3364.

References

External links

NGC 3516 on SIMBAD
{{Ursa Major Barred lenticular galaxies Seyfert galaxies Ursa Major Discoveries by William Herschel Astronomical objects discovered in 1785 3516 06153 33623