8C 1241+735
A weak emission-line radio galaxy in Draco.
8C 1241+735 is a radio galaxy located in the constellation of Draco. It is notable as a weak emission-line radio galaxy (WLRG) belonging to a small galaxy group, with a passive elliptical host galaxy and a core-jet radio morphology. Its radio spectrum is mainly flat, classifying it as a flat spectrum radio source.
- Constellation
- Draco
- Redshift
- 0.075
- Discovery year
- July 1996
- Apparent magnitude
- 17
- Radio spectrum type
- flat spectrum radio source
- Host galaxy type
- passive elliptical
- Radio morphology
- core-jet
Lore & Background
8C 1241+735 was first discovered as a bright astronomical radio source by astronomers in July 1996. It was subsequently identified with a 17 magnitude galaxy in a study by M. Stickel and H. Kuehr. The galaxy contains a radio spectrum that appears mainly flat, leading to its classification as a flat spectrum radio source.
The host galaxy is a passive elliptical with a core-jet radio morphology. When observed with MERLIN, it has a compact radio core described to show an extended radio component oriented at -30°. Radio observations made with the Very Large Array (VLA) identified this component as a diffused jet knot. The radio core itself is unpolarized.
A one-sided radio jet is present, extending 10 arcseconds from the core with an orientation of -20° on kiloparsec scales. On parsec scales, the jet has the same one-sided appearance and the same position angle, with a total extent of 15 milliarcseconds. The jet is bending toward the southwest and terminates at a compact component at -95° from the nucleus. The jet contains 12 percent polarization, with its polarized radio emission offset from the western jet edge; the electric vector position angle is parallel to the jet. Further imaging detected the presence of a LINER nucleus.
Reader's Guide
8C 1241+735 is significant as a weak emission-line radio galaxy (WLRG) that provides insight into the properties of radio galaxies with flat radio spectra. Its classification as a flat spectrum radio source, based on its mainly flat radio spectrum, distinguishes it from steep-spectrum sources. The galaxy's core-jet morphology, observed on both kiloparsec and parsec scales, reveals a one-sided jet that bends toward the southwest, terminating at a compact component. The jet's 12 percent polarization and the offset of polarized emission from the western jet edge, with the electric vector position angle parallel to the jet, offer details about the magnetic field structure. The presence of a LINER nucleus adds to the understanding of its nuclear activity. As a member of a small galaxy group, 8C 1241+735 also contributes to studies of galaxy evolution in group environments. Its discovery in July 1996 and subsequent identification with a 17 magnitude galaxy by M. Stickel and H. Kuehr underscore its role in the cataloging of radio sources.
Did You Know?
- The galaxy has a flat radio spectrum, classifying it as a flat spectrum radio source.
- Its radio jet is one-sided and extends 10 arcseconds on kiloparsec scales and 15 milliarcseconds on parsec scales.
Frequently Asked Questions
What is 8C 1241+735?
8C 1241+735 is a weak emission-line radio galaxy (WLRG) that sits within a small galaxy group in the northern sky. It is anchored by a passive elliptical host galaxy and displays a core-jet structure in its radio emission.
What kind of host galaxy does 8C 1241+735 have?
The host is a passive elliptical galaxy, meaning it shows little ongoing star formation and is dominated by older stellar populations. This quiet optical environment contrasts with the active radio jet emerging from its core.
Where in the sky can you find 8C 1241+735?
It resides in the constellation Draco, the Dragon, one of the smaller circumpolar constellations visible from mid-northern latitudes. At an apparent magnitude of 17, it is far too faint for casual backyard observation and requires dedicated radio or deep optical surveys to detect.
When was 8C 1241+735 first identified?
The source was catalogued in July 1996 during a radio survey campaign. Its flat-spectrum radio signature was the key characteristic that led it to be classified as a flat spectrum radio source at the time of discovery.
What is notable about 8C 1241+735's radio spectrum?
Its spectrum is predominantly flat, which places it in the flat spectrum radio source category and hints at a compact, possibly synchrotron-dominated jet region. Combined with its core-jet morphology, this suggests the central engine is still producing relativistic outflows despite the host's otherwise quiescent elliptical nature.
More in Elliptical and Irregular Galaxies, Part 2 1-24
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