Arp 147

Coordinates: Sky map 03h 11m 18.90s, +01° 18′ 52.99″

Arp 147
Arp 147
Interacting galaxies Arp 147
Observation data (J2000 epoch)
ConstellationCetus
Right ascension 03h 11m 18.90s
Declination+01° 18′ 52.99″
Redshift0.03141[1]
Helio radial velocity9,267 km/s[1]
Distance430–440 Mly
(134.9 mpc)[2]
Apparent magnitude (V)14.3
Characteristics
TypeSB bc
Mass~3.6 x 1011[3] M
Apparent size (V)0.650' x 0.286'[1]
Notable featuresmassive H II region
Other designations
VV 787, SDSS J031120.03+011858.4, IC 298/298A, PGC 11890

Arp 147 (also known as IC 298) is an interacting pair of ring galaxies. It lies 430 million[4] to 440 million light years away in the constellation Cetus and does not appear to be part of any significant galaxy group.[3] The system was originally discovered in 1893 by Stephane Javelle[5] and is listed in the Atlas of Peculiar Galaxies.

The system was formed when a spiral galaxy (image right) collided with an elliptical galaxy (image left).[6] The collision produced an expanding wave of star production (shown as bright blue) traveling at an effective speed of ≳100 km s−1 and began some 40 million years ago.[3] 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.[4]

The right-side galaxy is 30,000 light years in diameter[7] and is located 21,000 light years away from its partner galaxy.[8]:3 The entire system extends some 115,000 light years across.[6]

In September 2008, Hubble's main data-handling unit failed. After the problem was corrected, the telescope's Wide Field Planetary Camera 2 was aimed at Arp 147 and the quality of the images taken assured NASA that Hubble was working properly.[2][9]

Main ring

The main ring contains nine bright X-ray sources which are black holes, each with a mass 10–20 times the mass of the Sun.[6] The edge-to-edge expansion of the ring is 225 ± 8 km/s and there is very little rotation seen (47 ± 8 km/s).[10]:6

It also has a star formation rate of approximately 4.68 solar masses per year.[10]:7 The reddish bulge in the main ring is thought to be the original galactic nucleus of the primary galaxy[10]:1 and comprises 30–50% of the total mass of the galaxy.[10]:9

Smaller galaxy

The smaller companion galaxy (left side) also contains an X-ray source which may be a poorly fed black hole.[6]

References

  1. ^ a b c "IC 298". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved December 2, 2013.
  2. ^ a b "Hubble Scores a Perfect Ten: Fast Facts". National Aeronautics and Space Administration. October 30, 2008. Retrieved November 30, 2013.
  3. ^ a b c Rappaport, S.; Levine, A. (August 2, 2010). "Ultraluminous X-Ray Sources In Arp 147". The Astrophysical Journal. The American Astronomical Society. 721 (2): 1348–1355. arXiv:1007.3271. Bibcode:2010ApJ...721.1348R. doi:10.1088/0004-637X/721/2/1348. Retrieved November 30, 2013.
  4. ^ a b "Cosmic Valentine's Day Photo Reveals Black Hole Ring". Space.com. February 9, 2011. Retrieved December 1, 2013.
  5. ^ Courtney Seligman. "IC Objects: IC 250 – 299". CSeligman.com. Retrieved November 30, 2013.
  6. ^ a b c d "Arp 147: Giant Ring of Black Holes". Harvard-Smithsonian Center for Astrophysics. February 9, 2011. Retrieved November 30, 2013.
  7. ^ Nemiroff, R.; Bonnell, J., eds. (4 November 2008). "The Double Ring Galaxies of Arp 147 from Hubble". Astronomy Picture of the Day. NASA. Retrieved November 30, 2013.
  8. ^ Gerber, Richard; Lamb, Susan (November 1992). "A model for ring galaxies – ARP 147-like systems" (GIF). Astrophysical Journal Letters. The American Astronomical Society. 399 (1): L51–L54. Bibcode:1992ApJ...399L..51G. doi:10.1086/186604. Retrieved November 30, 2013.
  9. ^ Ian Sample (October 30, 2008). "Hubble out of trouble". The Guardian. Retrieved December 2, 2013.
  10. ^ a b c d Fogarty, Lisa; Niranjan, Thatte (May 2011). "SWIFT Observations of the Arp 147 Ring galaxy system". Monthly Notices of the Royal Astronomical Society. Royal Astronomical Society. 417: 1–11. arXiv:1105.4423. Bibcode:2011MNRAS.417..835F. doi:10.1111/j.1365-2966.2011.19066.x.
9 Ceti

9 Ceti is the Flamsteed designation for a star in the equatorial constellation of Cetus. It has an apparent visual magnitude of 6.39, which is below the limit that can be seen with the naked eye by a typical observer. (According to the Bortle scale, it is possible for some observers to see it from dark rural skies.) Based upon measurements made by the Hipparcos spacecraft, this star is around 68 light years away from the Sun. There is a magnitude 12.57 optical companion at an angular separation of 214 arc seconds along a position angle of 294° (as of 1999), although the pair are not physically associated as they have different proper motions.This is a solar analog, which is defined as a "Population I dwarf with gross properties not very different from those of the Sun". It is a G-type main sequence star with a stellar classification of G3 V, which means it is generating energy through the fusion of hydrogen into helium at its core. The mass and radius of the star are similar to the Sun, although the abundance of elements other than hydrogen and helium is about 50% greater. It is much younger than the Sun, being an estimated 850 million years of age. The effective temperature of the stellar atmosphere is around 5,807 K, giving it the yellow-hued glow of a G-type star.In 1980, this was found to be a variable star with a periodicity of 7.655 days, and it was given variable star designation BE Cet. This variation in luminosity was interpreted to be the result of rotational modulation of star spot activity in the photosphere, and hence it is classified as a BY Draconis variable. There is considerable variation in the strength of the surface activity—to the point where it has appeared inactive during some observation runs. The strength of the surface magnetic field was measured to be 450 G. The spectrum of this star includes lines of titanium oxide and calcium hydride, which, for a star of this class, is further evidence of star spot activity. Star spots cover an estimated 3% of the surface.This star has been examined for evidence of a planetary companion or a debris disk, but as of 2015 none has been found. The age of the star and its motion through space suggest that it is a member of the Hyades stellar kinematic group.

Atlas of Peculiar Galaxies

The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced by Halton Arp in 1966. A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the California Institute of Technology. The primary goal of the catalog was to present photographs of examples of the different kinds of peculiar structures found among galaxies.

Chi Ceti

Chi Ceti (χ Ceti), is the Bayer designation for a double star in the equatorial constellation of Cetus. They appear to be common proper motion companions, sharing a similar motion through space. The brighter component, HD 11171, is visible to the naked eye with an apparent visual magnitude of 4.66, while the fainter companion, HD 11131, is magnitude 6.75. Both lie at roughly the same distance, with the brighter component lying at an estimated distance of 75.6 light years from the Sun based upon an annual parallax shift of 43.13 mass.The primary, component A, is an evolved K-type giant star with a stellar classification of F3 III. However, Houk and Swift (1999) listed a classification of F0 V, which would match an F-type main sequence star. It displays an infrared excess at a wavelength of 70 μm and thus is a candidate host of an orbiting debris disk.The common proper motion companion, component B, is a G-type main sequence star with a classification of G3 V. It is a BY Draconis variable with a periodicity of 8.92 days and a variable star designation of EZ Cet.

Epsilon Ceti

Epsilon Ceti, Latinized from ε Ceti, is the Bayer designation for a binary star system located in the equatorial constellation of Cetus. It is faintly visible to the naked eye with an apparent visual magnitude of +4.84. Based upon an annual parallax shift of 14.58 mas, it is located around 98 light years away from the Sun.

This is a line-width spectroscopic binary star system. It has an orbital period of 2.65 years and an eccentricity of 0.23. The semimajor axis is 0.11 AU, or 11% of the distance between the Sun and the Earth, and the orbital plane is inclined at an angle of 24.2°.The primary member, component A, is an F-type main sequence star with a stellar classification of F2 V. The spectrum of the secondary, component B, can not be readily separated from that of the primary, so its type can only be estimated as a main sequence star lying in the range between F7 V and G4 V. The system is estimated to be 1.8 billion years old, with the primary having 1.4 times the mass of the Sun and the secondary being about equal to the Sun's mass.

Iota Ceti

Iota Ceti (ι Cet, ι Ceti) is the Bayer designation for a star system in the equatorial constellation of Cetus. It has the traditional name Deneb Kaitos Shemali. The name was from the Arabic word ذنب قيطس الشمالي - dhanab qayṭas al-shamālī, meaning the northern tail of the sea monster. it is visible to the naked eye with an apparent visual magnitude of 3.562. Based upon an annual parallax shift of 11.88 mas, it lies around 275 light years from the Sun.

In Chinese, 天倉 (Tiān Cāng), meaning Square Celestial Granary, refers to an asterism consisting of ι Ceti, η Ceti, θ Ceti, ζ Ceti, τ Ceti and 57 Ceti. Consequently, the Chinese name for ι Ceti itself is 天倉一 (Tiān Cāng yī, English: the First Star of Square Celestial Granary.)This is an MK-standard star with a stellar classification of K1.5 III, indicating that it is an evolved K-type giant star. However, Houk and Swift (1999) list a classification of K1 II, which would indicate this is a bright giant. It is a suspected variable with a visual amplitude of around 0.05 magnitude. The star has about 2.8 times the mass of the Sun, 34 times the Sun's radius, and radiates 398 times the solar luminosity from its outer atmosphere at an effective temperature of 4,446 K.Iota Ceti forms a wide astrometric pair with a common proper motion companion, a magnitude 10.40 star at an angular separation of 106.4 arcseconds along a position angle of 191° (as of 2014). This companion may be a K-type star.

Kappa2 Ceti

Kappa2 Ceti (κ2 Ceti), is a solitary, yellow-hued star located in the equatorial constellation of Cetus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.66. Based upon an annual parallax shift of 10.11 mas as seen from Earth, it is located about 320 light years from the Sun.

This is an evolved G-type giant star with a stellar classification of G8 III. It is a red clump star on the horizontal branch, which indicates it is generating energy through helium fusion at its core. The star has 2.46 times the mass of the Sun and has expanded to 8.2 times the Sun's radius. It is radiating 42 times the solar luminosity from its photosphere at an effective temperature of 5,007 K.

List of ring galaxies

This is a list of ring galaxies. A ring galaxy is a galaxy with a circle-like appearance. Hoag's Object, discovered by Art Hoag in 1950, is the prototypical example of a ring galaxy.

Phi1 Ceti

Phi1 Ceti is a star located in the equatorial constellation Cetus. It is visible to the naked eye with an apparent visual magnitude of +4.78. Based upon an annual parallax shift of 13.96 mas, it is located about 234 light years from the Sun.

At an age of about 2.21 billion years, this is an evolved red clump giant star with a stellar classification of K0 III. It is presently on the horizontal branch and is generating energy through the nuclear fusion of helium at its core. The star is suspected of variability; it has been measured to vary between magnitudes 4.75 and 4.78.Based upon the motion of this star through space, Phi1 Ceti is a probable member of the proposed Wolf 630 moving group. This is a set of stars centered on Wolf 630 that are moving nearly in parallel and have an age of around 2.7±0.5 billion years. They may be former members of a dissolved open cluster.

Phi3 Ceti

Phi3 Ceti is a solitary, orange-hued star in the equatorial constellation of Cetus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.31. Based upon an annual parallax shift of 5.92 mas as seen from Earth, it is located roughly 550 light years from the Sun, give or take 30 light years.

This is an evolved K-type giant star with a stellar classification of K5 III. The measured angular diameter of Phi3 Ceti is 2.42±0.13 mas. At the estimated distance of the star, this yields a physical size of about 44 times the Sun's radius. It has about 1.4 times the mass of the Sun and radiates 429 times the solar luminosity from its photosphere at an effective temperature of 3,940 K.

Phi4 Ceti

Phi4 Ceti is a solitary, orange-hued star in the equatorial constellation Cetus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.61. Based upon an annual parallax shift of 10.20 mas as seen from Earth, it is located roughly 320 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.10 due to interstellar dust.This is an evolved G-type giant star with a stellar classification of G8 III. It is a red clump star on the horizontal branch, which indicates it is generating energy through helium fusion at its core. The star has about 1.76 times the mass of the Sun and has expanded to ten times the Sun's radius. It is radiating 60 times the solar luminosity from its photosphere at an effective temperature of 4,903 K.

Pi Ceti

Pi Ceti, Latinized from π Ceti, is the Bayer designation for a star system in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 4.238. Based upon an annual parallax shift of 8.30 mas, it is located around 393 light years from the Sun.

This is a single-lined spectroscopic binary system with a nearly circular orbit and a period of 7.45 years. The fact that the system has a negligible eccentricity is surprising for such a long period, and may suggest that the secondary is a white dwarf that had its orbit circularized during a mass-transfer event.The primary, component A, is a normal B-type star that has been given stellar classifications of B7 V and B7 IV. It appears very young – less than half a million years in age – and may still be on a pre-main sequence track. The star shows no magnetic field but it does emit an infrared excess.

Rho Ceti

Rho Ceti , Latinized from ρ Ceti, is the Bayer designation for a star in the equatorial constellation of Cetus. It is faintly visible to the naked eye with an apparent visual magnitude of 4.885. The distance to this star, based upon an annual parallax shift of 7.15 mas, is around 460 light years.

This is an A-type main sequence star with a stellar classification of A0 V. It is spinning rapidly with a projected rotational velocity of 219 km/s, giving the star an oblate shape with an equatorial bulge that is 10% larger than the polar radius. The star has an estimated size 3.1 times the radius of the Sun and is radiating 178 times the solar luminosity from its outer atmosphere at an effective temperature of 8,905 K.

Ring galaxy

A ring galaxy is a galaxy with a circle-like appearance. Hoag's Object, discovered by Art Hoag in 1950, is an example of a ring galaxy. The ring contains many massive, relatively young blue stars, which are extremely bright. The central region contains relatively little luminous matter. Some astronomers believe that ring galaxies are formed when a smaller galaxy passes through the center of a larger galaxy. Because most of a galaxy consists of empty space, this "collision" rarely results in any actual collisions between stars. However, the gravitational disruptions caused by such an event could cause a wave of star formation to move through the larger galaxy. Other astronomers think that rings are formed around some galaxies when external accretion takes place. Star formation would then take place in the accreted material because of the shocks and compressions of the accreted material.

Sigma Ceti

Sigma Ceti (σ Ceti) is the Bayer designation for a star in the equatorial constellation of Cetus. With an apparent visual magnitude of 4.78, it can be seen with the naked eye on a dark night. Based upon an annual parallax shift of 37.46 mas, it lies at an estimated distance of 87.1 light years from the Sun. It is a probable astrometric binary star system.The primary, component A, appears to be a normal F-type main sequence star with a stellar classification of F5 V. However, Malaroda (1975) assigned it a classification of F4 IV, which would suggest it is a more evolved subgiant star. It is estimated to have 121% of the Sun's mass and around 150% of the radius of the Sun. With an age of about 2.1 billion years, it is radiating 7.6 times the solar luminosity from its outer atmosphere at an effective temperature of 6,527 K.

Theta Ceti

Theta Ceti, Latinized from θ Ceti, is a solitary, orange-hued star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.60. Based upon an annual parallax shift of 28.66 mas as seen from Earth, it is located about 114 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.10 due to interstellar dust.With an age of about 2.2 billion years, this is an evolved, K-type giant star with a stellar classification of K0 III. It is a red clump star on the horizontal branch, which means it is generating energy through helium fusion at its core. The star has an estimated 1.8 times the mass of the Sun and has expanded to 10 times the Sun's radius. It is radiating 53 times the solar luminosity from its photosphere at an effective temperature of 4,660 K.

Upsilon Ceti

Upsilon Ceti, Latinized from υ Ceti, is a solitary star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.95. Based upon an annual parallax shift of 11.14 mas, it is located about 293 light years from the Sun.

This star was designated Upsilon Ceti by Bayer and 59 Ceti by Flamsteed. Flamsteed also gave it the designation Upsilon2 Ceti to distinguish it from 56 Ceti, which he called Upsilon1. Flamsteed's superscripted designations, however, are not in general use today.For ancient Arabic astronomers, this star with η Cet (Deneb Algenubi), θ Cet (Thanih al Naamat), τ Cet (Durre Menthor) and ζ Cet (Baten Kaitos), formed Al Naʽāmāt (النعامات), the Hen Ostriches In Chinese, 鈇鑕 (Fū Zhì), meaning Sickle, refers to an asterism consisting of υ Ceti, 48 Ceti and 56 Ceti. Consequently, the Chinese name for υ Ceti itself is 鈇鑕四 (Fū Zhì sì, English: the Fourth Star of Sickle.)Upsilon Ceti is a evolved red giant star with a stellar classification of M0III and is listed as a standard for that class. The star has previously been classified as K5/M0III, an interesting example of one of the "gaps" in the Morgan-Keenan classification system, with K6-9 often not used for giant stars or used only to indicate a fraction of the way between K5 and M0.There is an 84% chance that it is on the red giant branch, or 16% to be on the horizontal branch. Stellar models based on the red giant branch status yield an estimated mass of around 126% of the Sun's mass and 54 times the radius of the Sun. This model indicates the star radiates around 550 times the solar luminosity from its outer atmosphere at an effective temperature of 3,822 K.

Zeta Ceti

Zeta Ceti (ζ Ceti, abbreviated Zeta Cet, ζ Cet) is a binary star in the equatorial constellation of Cetus. It has a combined apparent visual magnitude of 3.74, which is bright enough to be seen with the naked eye. Based upon parallax measurements taken during the Hipparcos mission, it is approximately 235 light-years from the Sun.Zeta Ceti is the primary or 'A' component of a double star system designated WDS J01515-1020 (the secondary or 'B' component is HD 11366). Zeta Ceti's two components are therefore designated WDS J01515-1020 Aa and Ab. Aa is officially named Baten Kaitos , the traditional name of the entire system.

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