Abell 30

Last updated
Abell 30
Emission nebula
Planetary nebula
Abell 30 xray-optical composite.jpg
Composite image of Abell 30 in optical light and X-rays [1]
Observation data: J2000.0 epoch
Right ascension 08h 46m 53s [2]
Declination 17° 52′ 46″ [2]
Distance5,500  ly
Apparent magnitude (V)14.3 [2]
Apparent dimensions (V)0.29′ × 0.13′ [2]
Constellation Cancer
Notable featuresborn-again nebula
DesignationsPK 208+33 1, Abell 30, IRAS F08440+1803, GALEX J084653.4+175248, 2MASS J08465346+1752463
See also: Lists of nebulae

Abell 30 is a planetary nebula located in the constellation of Cancer, at a distance of 5,500 light years. It belongs in the rare category of born-again planetary nebulae, in which stellar activity started up again after the creation of the planetary nebula. [1]

Contents

History

The planetary nebula was discovered by George O. Abell in photographic plates obtained during the Palomar Sky Survey. The discovery was published in 1966 in a list of 86 of old faint planetary nebulae known as the Abell Catalog of Planetary Nebulae. [3] In 1979 it was found that the centre of the Abell 30, as well as Abell 78, was noticeably hotter and brighter than the rest of the nebula and features knots which were not visible in H-alpha. [4] The mechanism that lead to the creation of the central knots was descripted in 1983. [5]

Formation

A planetary nebula is formed in the late stage of the evolution of a sun-like star. After having steadily produced energy for several billion years through the nuclear fusion of hydrogen into helium in its central region, or core, the star undergoes a series of energy crises related to the depletion of hydrogen and subsequent contraction of the core. These crises culminate in the star expanding a hundred-fold to become a red giant. [6]

Eventually the outer envelope of the red giant is ejected and moves away from the star at a relatively sedate speed of less than 100,000 miles per hour. The star meanwhile is transformed from a cool giant into a hot, compact star known as a white dwarf that produces intense ultraviolet radiation and a fast wind of particles moving at about 6 million miles per hour. The interaction of the UV radiation and the fast wind with the ejected red giant envelope creates the planetary nebula, creating a large spherical shell. [6] The outer shell has an observed age of 12,500 years. [1]

In rare cases, the helium shell of the star reaches critical mass and fuses into carbon and oxygen in the region surrounding the star’s core and heats the outer envelope of the star so much that it temporarily becomes a red giant again, in what is known as a very late thermal pulse. [7] The sequence of events – envelope ejection followed by a fast stellar wind – is repeated on a much faster scale than before, and a small-scale planetary nebula is created inside the original one. In a sense, the planetary nebula is reborn. [6] This new activity created the knots in the inner part of the nebula. [1] The expansion rate of the knots when observed by Hubble Space Telescope across a time span of 20 years indicates they have an age of 610 to 950 years. [7]

Morphology

The knots in the centre of Abell 30 by Hubble Space Telescope. Abell 30 optical close.jpg
The knots in the centre of Abell 30 by Hubble Space Telescope.

Abell 30 consists of an outer shell, a faint cloverleaf pattern, and a central star that is surrounded by knots. The outer shell has a radius of 63 arcseconds and brightens gradually up to a sharp edge. The cloverleaf pattern is more pronounced towards the southeast and southwest and reaches 26 arcseconds from the centre, almost half away to the edge. [4]

The brightest knots lie within 10 arcseconds from the central star. Although originally four knots were identified, named J1 to J4, higher resolution images of the images revealed that they were composed of smaller knots and filaments. [8] These smaller knots are cometary in appearance, with a length of several arcseconds and a width of less than half an arcsecond. The nebula has two bright polar knots, lying about seven arcseconds from the central star, [9] and both feature a bow shock towards the central star. The other knots are arranged in a disk like the spokes of a wheel seen at an inclination of 60 degrees. To the southwest, where the bright knots are located, the knots form a fan. [10]

The infrared morphology of the nebula is quite different. It features smooth disk-like emission extending along a northeast to southwest axis, passing through the central star and knot J4, while no enhancement is seen at knots J1 and J3. Along the axis also lie the brightest parts of the outer shell of the nebula. [11] The X-ray emission of the nebula consists of a point source at the central star and diffuse emission associated with the knots and the cloverleaf structure. The diffuse emission is possibly the result of the material in the knots getting hit by the fast stellar wind and heated into plasma. [12]

The central star of the planetary nebula has been found to have a spectral type between a carbon rich Wolf–Rayet star and a PG 1159 star, and is categorised as a [WC]-PG 1159 star. [13] Its temperature is estimated to be 110,000 K. The star appears to be variable, with a period of 1.06 days. It is possible that the presence of a colder and dimmer companion is the source of the variability observed. [13]

Composition

The central region of the nebula is notably depleted in hydrogen when observed in H-alpha emission and the knots appear to be rich in helium and lack hydrogen emission. More over, the composition of the knots isn't uniform. The abundance of helium indicates that all the hydrogen has been converted to helium. [14] Also, oxygen, nitrogen and neon were detected in expected quantities, while carbon abundances were elevated. When the high abundance of carbon in the knot J3 was detected, derived by the λ4267 line, it was questioned. [14] However the high abundance of carbon was also observed in the ultraviolet spectrum of the nebula. [15]

A more detailed spectral analysis confirmed the chemical segregation of the knots. The polar knots (J1 and J3) have higher helium to hydrogen ratio, with 7 times more helium than hydrogen, than the other knots, where the He/H ratio is about 4. [16] Also the abundances of oxygen and nitrogen in the polar knots is about an order of magnitude lower than those observed in planetary nebula while neon is about three times less. Contrary, knot 4 has the expected abundances of oxygen and nitrogen. [16] The oxygen recombination lines indicate that the polar knots have cool, yet ionised carbon, oxygen and nitrogen in their core. The temperatures calculated from the oxygen recombination lines are 500 K for J1 and 2500 K for J3. [17]

Around the central star carbon dust has been discovered in the infrared, lying at the same location with the knots. The total dust mass is estimated to be 3.20+3.21
−2.06×10−3  M☉ . Accounting for the carbon embedding in the dust, there is more carbon than oxygen in the ejecta of the nebula, favoring the very late thermal pulse model. The carbon dust is expected to destroyed around the central star and be pussed away by radiation pressure. [18]

See also

Related Research Articles

<span class="mw-page-title-main">Planetary nebula</span> Type of emission nebula created by dying red giants

A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.

<span class="mw-page-title-main">Ring Nebula</span> Planetary nebula in Lyra

The Ring Nebula is a planetary nebula in the northern constellation of Lyra.[C] Such a nebula is formed when a star, during the last stages of its evolution before becoming a white dwarf, expels a vast luminous envelope of ionized gas into the surrounding interstellar space.

<span class="mw-page-title-main">H II region</span> Large, low-density interstellar cloud of partially ionized gas

An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about a million particles per cubic centimetre. The Orion Nebula, now known to be an H II region, was observed in 1610 by Nicolas-Claude Fabri de Peiresc by telescope, the first such object discovered.

<span class="mw-page-title-main">Wolf–Rayet star</span> Heterogeneous class of stars with unusual spectra

Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. The surface temperatures of known Wolf–Rayet stars range from 20,000 K to around 210,000 K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their spectral classification.

<span class="mw-page-title-main">Cat's Eye Nebula</span> Planetary nebula in the constellation Draco

The Cat's Eye Nebula is a planetary nebula in the northern constellation of Draco, discovered by William Herschel on February 15, 1786. It was the first planetary nebula whose spectrum was investigated by the English amateur astronomer William Huggins, demonstrating that planetary nebulae were gaseous and not stellar in nature. Structurally, the object has had high-resolution images by the Hubble Space Telescope revealing knots, jets, bubbles and complex arcs, being illuminated by the central hot planetary nebula nucleus (PNN). It is a well-studied object that has been observed from radio to X-ray wavelengths. At the centre of the Cat's Eye Nebula is a dying Wolf Rayet star, the sort of which can be seen in the Webb Telescope's image of WR 124. The Cat's Eye Nebula's central star shines at magnitude +11.4. Hubble Space Telescope images show a sort of dart board pattern of concentric rings emanating outwards from the centre.

<span class="mw-page-title-main">Asymptotic giant branch</span> Stars powered by fusion of hydrogen and helium in shell with an inactive core of carbon and oxygen

The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars. This is a period of stellar evolution undertaken by all low- to intermediate-mass stars (about 0.5 to 8 solar masses) late in their lives.

<span class="mw-page-title-main">NGC 7027</span> Planetary nebula in the constellation Cygnus

NGC 7027, also known as the Jewel Bug Nebula or the Magic Carpet Nebula, is a very young and dense planetary nebula located around 3,000 light-years from Earth in the constellation Cygnus. Discovered in 1878 by Édouard Stephan using the 800 mm (31 in) reflector at Marseille Observatory, it is one of the smallest planetary nebulae and by far the most extensively studied.

<span class="mw-page-title-main">Protoplanetary nebula</span> Nebula surrounding a dying star

A protoplanetary nebula or preplanetary nebula is an astronomical object which is at the short-lived episode during a star's rapid evolution between the late asymptotic giant branch (LAGB)[a] phase and the subsequent planetary nebula (PN) phase. A PPN emits strongly in infrared radiation, and is a kind of reflection nebula. It is the second-from-the-last high-luminosity evolution phase in the life cycle of intermediate-mass stars.

<span class="mw-page-title-main">Sakurai's Object</span> Star in the constellation Sagittarius

Sakurai's Object is a star in the constellation of Sagittarius. It is thought to have previously been a white dwarf that, as a result of a very late thermal pulse, swelled and became a red giant. It is located at the center of a planetary nebula and is believed to currently be in thermal instability and within its final shell helium flash phase.

<span class="mw-page-title-main">NGC 5307</span> Planetary nebula in the constellation Centaurus

NGC 5307 is a planetary nebula in the southern constellation of Centaurus, positioned less than 3° to the northeast of the star Epsilon Centauri. It was discovered by English astronomer John Herschel on April 15, 1836. The nebula is located at a distance of approximately 10.6 kilolight-years from the Sun. The central star, designated PNG 312.3+10.5, is a weak emission-line star, superficially similar to the WC subtype of Wolf–Rayet stars. It has a spectral class of O(H)3.5 V.

A PG 1159 star, often also called a pre-degenerate, is a star with a hydrogen-deficient atmosphere that is in transition between being the central star of a planetary nebula and being a hot white dwarf. These stars are hot, with surface temperatures between 75,000 K and 200,000 K, and are characterized by atmospheres with little hydrogen and absorption lines for helium, carbon and oxygen. Their surface gravity is typically between 104 and 106 meters per second squared. Some PG 1159 stars are still fusing helium., § 2.1.1, 2.1.2, Table 2. The PG 1159 stars are named after their prototype, PG 1159-035. This star, found in the Palomar-Green survey of ultraviolet-excess stellar objects, was the first PG 1159 star discovered.

<span class="mw-page-title-main">Abell 39</span> Nebula in the constellation Hercules

Abell 39 is a low surface brightness planetary nebula in the constellation of Hercules. It is the 39th entry in George Abell's 1966 Abell Catalog of Planetary Nebulae of 86 old planetary nebulae which either Abell or Albert George Wilson discovered before August 1955 as part of the National Geographic Society - Palomar Observatory Sky Survey. It is estimated to be about 3,800 light-years from earth and thus 2,600 light-years above the Galactic plane. It is almost perfectly spherical and also one of the largest known spheres with a radius of about 1.4 light-years.

<span class="mw-page-title-main">Red giant</span> Type of large cool star

A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around 5,000 K [K] or lower. The appearance of the red giant is from yellow-white to reddish-orange, including the spectral types K and M, sometimes G, but also class S stars and most carbon stars.

<span class="mw-page-title-main">NGC 6072</span> Emission planetary nebula in the constellation Scorpius

NGC 6072 is a planetary nebulae in the southern constellation of Scorpius. It has a dynamical age of 104 years. Its circumstellar envelope is likely to be rich in carbon as it has very strong CN (cyanide) spectral lines. CN spectral lines are generally not detected in oxygen rich AGB (asymptotic giant branch) circumstellar envelopes. NGC 6072 also shows H2 (hydrogen) emission and intense CO (carbon monoxide) emission which has been mapped displaying bipolarity and some gas at high velocity. The evolution of this planetary nebulae is likely to be dominated by photodissociation and ion/radical molecular reactions. Shock chemistry is also likely to be important.

<span class="mw-page-title-main">V605 Aquilae</span> Star in the constellation Aquila

V605 Aquilae, in the constellation Aquila, is the variable central star of the planetary nebula Abell 58. It is a highly unusual hydrogen-deficient carbon-rich star.

<span class="mw-page-title-main">Abell 78</span> Planetary nebula in the constellation of Cygnus

Abell 78 is a planetary nebula located in the constellation of Cygnus at a distance of about 5,000 light years. It has a fainter halo consisting mostly hydrogen, an inner elliptical ring that is mostly made of helium and some inner knots that surround the central star and are extremely depleted in hydrogen. These inner knots were created by a very late thermal pulse, a re-ignition of thermonuclear activity in the helium shell of the star observed after the star left the asymptotic giant branch and is accompanied by strong stellar winds.

<span class="mw-page-title-main">Cometary knot</span> Structure in some planetary nebulae

Cometary knots, also referred as globules, are structures observed in several nearby planetary nebulae (PNe), including the Helix Nebula, the Ring Nebula, the Dumbbell Nebula, the Eskimo Nebula, and the Retina Nebula. They are believed to be a common feature of the evolution of planetary nebulae, but can only be resolved in the nearest examples. They are generally larger than the size of the Solar System, with masses of around 0.00001 times the mass of the Sun, which is comparable to the mass of the Earth. There are about 40,000 cometary knots in the Helix Nebula.

<span class="mw-page-title-main">NGC 6905</span> Planetary nebula in the constellation Delphinus

NGC 6905, also known as the Blue Flash Nebula, is a planetary nebula in the constellation Delphinus. It was discovered by William Herschel in 1784. The central star is 14.0 mag. The distance of the nebula, as with most planetary nebulae, is not well determined and estimates range between 1.7 and 2.6 kpc.

<span class="mw-page-title-main">KjPn 8</span> Bipolar planetary nebula

KjPn 8 is a bipolar planetary nebula which was discovered by M.A. Kazaryan and Eh. S. Parsamyan in 1971 and independently by Luboš Kohoutek in 1972.

<span class="mw-page-title-main">Abell 35</span> Nebula located in the constellation of Hydra

Abell 35, also known as Sh 2-313, is a nebula located in the constellation of Hydra, at a distance of 400 light years. The nebula is characterised by its unusual appearance, which features a central bow shock surrounded by symmetric emission. In the centre of the nebula lies a binary star, composed of a G-type star and a white dwarf. Although it is commonly referred to as a planetary nebula, it has been suggested that the nebula wasn't created by a post-AGB star shedding its outer shells but it is interstellar medium photoionised by the passing binary system, leading also to the creation of the bow shock.

References

  1. 1 2 3 4 "Abell 30: X-rays from a Reborn Planetary Nebula". chandra.harvard.edu. Retrieved 15 November 2024.
  2. 1 2 3 4 "PN A66 30". simbad.cds.unistra.fr. Retrieved 10 November 2024.
  3. ↑ Abell, G. O. (April 1966). "Properties of Some Old Planetary Nebulae". The Astrophysical Journal. 144: 259. Bibcode:1966ApJ...144..259A. doi:10.1086/148602.
  4. 1 2 Jacoby, G. H. (December 1979). "Unusual structure in the planetary nebulae Abell 30 and Abell 78". Publications of the Astronomical Society of the Pacific. 91: 754. Bibcode:1979PASP...91..754J. doi:10.1086/130582.
  5. ↑ Iben, I., Jr.; Kaler, J. B.; Truran, J. W.; Renzini, A. (January 1983). "On the evolution of those nuclei of planetary nebulae that experience a final helium shell flash". The Astrophysical Journal. 264: 605. Bibcode:1983ApJ...264..605I. doi:10.1086/160631.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. 1 2 3 "A Reborn Planetary Nebula - NASA". nasa.gov. 16 November 2012. Retrieved 15 November 2024.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  7. 1 2 Fang, X.; Guerrero, M. A.; Marquez-Lugo, R. A.; Toalá, J. A.; Arthur, S. J.; Chu, Y.-H.; Blair, W. P.; Gruendl, R. A.; Hamann, W.-R.; Oskinova, L. M.; Todt, H. (5 December 2014). "Expansion of Hydrogen-Poor Knots in the Born-Again Planetary Nebulae A30 and A78". The Astrophysical Journal. 797 (2): 100. arXiv: 1410.3872 . Bibcode:2014ApJ...797..100F. doi:10.1088/0004-637X/797/2/100.
  8. ↑ Rodríguez-González, J B; Santamaría, E; Toalá, J A; Guerrero, M A; Montoro-Molina, B; Rubio, G; Tafoya, D; Chu, Y-H; Ramos-Larios, G; Sabin, L (6 July 2022). "Common envelope evolution in born-again planetary nebulae – Shaping the H-deficient ejecta of A 30". Monthly Notices of the Royal Astronomical Society. 514 (4): 4794–4802. doi: 10.1093/mnras/stac1697 .
  9. ↑ Borkowski, Kazimierz J.; Harrington, J. P.; Tsvetanov, Zlatan; Clegg, Robin E. S. (September 1993). "HST imaging of hydrogen-poor ejecta in Abell 30 and Abell 78 - Wind-blown cometary structures". The Astrophysical Journal. 415: L47. Bibcode:1993ApJ...415L..47B. doi:10.1086/187029.
  10. ↑ Borkowski, Kazimierz J.; Harrington, J. Patrick; Tsvetanov, Zlatan I. (20 August 1995). "Interaction of a Stellar Wind with Clumpy Stellar Ejecta in A30". The Astrophysical Journal. 449 (2). Bibcode:1995ApJ...449L.143B. doi:10.1086/309643.
  11. ↑ Dinerstein, H. L.; Lester, D. F. (June 1984). "Evidence for an infrared disk in the core of the extraordinary planetary nebula Abell 30". The Astrophysical Journal. 281: 702. Bibcode:1984ApJ...281..702D. doi:10.1086/162147.
  12. ↑ Guerrero, M. A.; Ruiz, N.; Hamann, W.-R.; Chu, Y.-H.; Todt, H.; Schönberner, D.; Oskinova, L.; Gruendl, R. A.; Steffen, M.; Blair, W. P.; Toalá, J. A. (20 August 2012). "Rebirth of X-Ray Emission from the Born-Again Planetary Nebula A30". The Astrophysical Journal. 755 (2): 129. arXiv: 1202.4463 . Bibcode:2012ApJ...755..129G. doi:10.1088/0004-637X/755/2/129.
  13. 1 2 Jacoby, George H; Hillwig, Todd C; Jones, David (11 October 2020). "Abell 30 - A binary central star among the born-again planetary nebulae". Monthly Notices of the Royal Astronomical Society: Letters. 498 (1): L114–L118. doi: 10.1093/mnrasl/slaa138 .
  14. 1 2 Jacoby, G. H.; Ford, H. C. (March 1983). "The hydrogen-depleted planetary nebulae Abell 30 and Abell 78". The Astrophysical Journal. 266: 298. Bibcode:1983ApJ...266..298J. doi:10.1086/160779.
  15. ↑ Harrington, J. P.; Feibelman, W. A. (February 1984). "The remarkable ultraviolet spectrum of the planetary nebula Abell 30". The Astrophysical Journal. 277: 716. Bibcode:1984ApJ...277..716H. doi:10.1086/161743.
  16. 1 2 Guerrero, M. A.; Manchado, A. (December 1996). "The Chemical Abundances of the Hydrogen-poor Planetary Nebulae A30 and A58". The Astrophysical Journal. 472 (2): 711–722. Bibcode:1996ApJ...472..711G. doi:10.1086/178101.
  17. ↑ Wesson, R.; Liu, X.- W.; Barlow, M. J. (21 March 2003). "Physical conditions in the planetary nebula Abell 30". Monthly Notices of the Royal Astronomical Society. 340 (1): 253–263. arXiv: astro-ph/0301119 . Bibcode:2003MNRAS.340..253W. doi: 10.1046/j.1365-8711.2003.06289.x .
  18. ↑ Toalá, J A; Jiménez-Hernández, P; Rodríguez-González, J B; Estrada-Dorado, S; Guerrero, M A; Gómez-González, V M A; Ramos-Larios, G; García-Hernández, D A; Todt, H (19 March 2021). "Carbon dust in the evolved born-again planetary nebulae A 30 and A 78". Monthly Notices of the Royal Astronomical Society. 503 (1): 1543–1556. doi: 10.1093/mnras/stab593 .
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.