Arp 147
Interacting ring galaxies formed by a disk-disk collision.
X-ray: NASA/CXC/MIT/S.Rappaport et al, Optical: NASA/STScI · Public domain
Arp 147 (also known as IC 298) is an interacting pair of ring galaxies located in the constellation Cetus, approximately 430 million to 440 million light years away. It was discovered in 1893 by Stephane Javelle and is listed in the Atlas of Peculiar Galaxies. The system formed when two disk galaxies collided, producing an expanding wave of star formation that began some 40 million years ago.
- diameter
- Not widely established
Quick Facts
- Epoch
- J2000
- Mass
- ~3.6 × 10 / 11
- Ra
- 03 · 11 · 18.90
- Dec
- +01 · 18 · 52.99
- Dist Ly
- 430–440 Mly / (134.9 mpc)
- Z
- 0.03141
- H Radial V
- 9,267 km/s
- Appmag V
- 14.3
- Size V
- 0.650' × 0.286'
- Constellation Name
- Cetus
- Notes
- massive H II region
- Names
- VV=787 · SDSS=J031120.03+011858.4 · IC=298/298A · PGC=11890
Facts from the source article.
Lore & Background
The system Arp 147 was formed when two disk galaxies collided. The collision produced an expanding wave of star production, shown as bright blue, traveling at an effective speed of ≳100 km/s. The most extreme period of star formation is estimated to have ended 15 million years ago, and as the young, super hot stars died as exploding supernovas, they left behind neutron stars and black holes. The right-side galaxy is 30,000 light years in diameter and is located 21,000 light years away from its partner galaxy.
Reader's Guide
Arp 147 is significant as a striking example of a ring galaxy system formed by a galactic collision, providing insight into the dynamics of star formation triggered by such interactions. The main ring contains nine bright X-ray sources identified as black holes, each with a mass 10–20 times that of the Sun, and exhibits an edge-to-edge expansion of 225 ± 8 km/s with very little rotation. The system's star formation rate is approximately 4.68 solar masses per year. In September 2008, after a failure of Hubble's main data-handling unit, the telescope's Wide Field Planetary Camera 2 was aimed at Arp 147, and the quality of the images assured NASA that Hubble was working properly. The smaller companion galaxy also contains an X-ray source that may be a poorly fed black hole.
Did You Know?
- Arp 147 was discovered in 1893 by Stephane Javelle.
- The main ring contains nine bright X-ray sources, each a black hole with mass 10–20 times the Sun's mass.
- The most extreme period of star formation in the system ended about 15 million years ago.
- In September 2008, Hubble's images of Arp 147 confirmed the telescope was working properly after a data-handling unit failure.
Gallery
Frequently Asked Questions
What is Arp 147?
Arp 147, also catalogued as IC 298, is a pair of ring-shaped galaxies currently locked in an interaction. It resides in the constellation Cetus and holds a place in the well-known Atlas of Peculiar Galaxies.
How did Arp 147's ring structure form?
The rings are the aftermath of two disk galaxies slamming into one another, sending a shockwave rippling outward through both disks. That impact ignited a broad wave of new star formation roughly 40 million years ago, and the expanding rings are the visible trace of that ancient collision.
How far away is Arp 147 from Earth?
The system sits approximately 430 to 440 million light years out in the direction of Cetus, making it a distant but observable target for ground- and space-based telescopes.
Who first identified Arp 147?
French astronomer Stephane Javelle first recorded the object in 1893. It was later picked up by George Arp for his catalog of unusual galaxy morphologies, which is how it got its familiar 'Arp' designation.
Why do astronomy fans find Arp 147 so compelling?
It gives observers a real-time snapshot of a disk-disk collision still in progress, with the expanding rings acting as a visible scar from the impact. The ongoing star-formation wave makes it a go-to example for understanding how galaxy mergers reshape structure and trigger new stellar populations.
More in Astronomical X-ray sources 1-24
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