NGC 3599
Lenticular galaxy in Leo with a variable X-ray source.
NGC 3599 is a lenticular galaxy in the constellation Leo, first observed by William Herschel on March 14, 1784. It lies about 20.4 megaparsecs from the Sun and belongs to the Leo II group of galaxies, which is part of the Virgocentric flow. Its morphological classification is SA0:, indicating a lenticular shape with some uncertainty. The galaxy features a faint ring structure around its nucleus and a small bar, and it is inclined at roughly 28° to the sky, making it appear nearly face-on. The nucleus is compact and shows no signs of non-thermal activity, yet the galaxy is classified as either a Seyfert 2 or a LINER type. The central black hole has an estimated mass. In 2003, a sudden increase in X-ray emission was detected by the XMM-Newton observatory, followed by a rapid decline in flux over subsequent years. This event was initially considered a candidate tidal disruption event, but may instead have resulted from thermal instability in the accretion disk around the black hole.
Quick Facts
- Epoch
- J2000
- Constellation Name
- Leo
- Ra
- 11 · 15 · 26.949
- Dec
- +18 · 06 · 37.43
- Z
- 0.00277
- Dist Ly
- 20.4 Mpc
- Appmag V
- 10.178
Facts from the source article.
Lore & Background
NGC 3599 is a lenticular galaxy with a morphological classification of SA0:, indicating some uncertainty. It has a weak ring structure around the nucleus and a small bar. The galaxy is inclined at 28° to the plane of the sky, making it nearly face-on. Its nucleus is compact and not associated with non-thermal activity, though it is classified as a Seyfert 2 or LINER-type galaxy. The mass of the central black hole is estimated but not specified in the available data.
In 2003, the XMM-Newton space observatory detected a sudden rise in X-ray emission from NGC 3599. Follow-up observations showed a rapid decay in flux over the following years. This event was originally suggested as a candidate tidal disruption event, but it may instead have been caused by thermal instability of the accretion disk orbiting the black hole.
NGC 3599 is a member of the Leo II group of galaxies, which lies within the Virgocentric flow. Its distance from the Sun is 20.4 Mpc.
Reader's Guide
NGC 3599 holds significance as a lenticular galaxy with an ambiguous active nucleus, classified as either Seyfert 2 or LINER, yet lacking non-thermal activity in its compact nucleus. Its most notable feature is the 2003 X-ray flare observed by XMM-Newton, which sparked debate over its origin—whether a tidal disruption event or thermal instability in the accretion disk. This event highlights the galaxy's potential for studying accretion processes around supermassive black holes. As a member of the Leo II group, it contributes to understanding galaxy dynamics within the Virgocentric flow. The galaxy's nearly face-on orientation and weak ring structure provide additional morphological interest, though its classification remains uncertain. The legacy of NGC 3599 lies in its role as a case study for transient X-ray phenomena in otherwise quiescent galaxies, offering insights into black hole accretion and variability.
Did You Know?
- NGC 3599 was discovered by William Herschel on March 14, 1784.
- A sudden rise in X-ray emission was observed in 2003 by XMM-Newton.
- The galaxy is classified as either Seyfert 2 or LINER-type, though not optically active.
More in NGC Objects, Part 6 1-24
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