Owl Nebula

The Owl Nebula (also known as Messier 97, M97 or NGC 3587) is a planetary nebula located approximately 2,030 light years away in the constellation Ursa Major.[2] It was discovered by French astronomer Pierre Méchain on February 16, 1781.[5] When William Parsons, 3rd Earl of Rosse, observed the nebula in 1848, his hand-drawn illustration resembled an owl's head. It has been known as the Owl Nebula ever since.[6]

The nebula is approximately 8,000 years old.[7] It is approximately circular in cross-section with a little visible internal structure. It was formed from the outflow of material from the stellar wind of the central star as it evolved along the asymptotic giant branch.[4] The nebula is arranged in three concentric shells, with the outermost shell being about 20–30% larger than the inner shell.[8] The owl-like appearance of the nebula is the result of an inner shell that is not circularly symmetric, but instead forms a barrel-like structure aligned at an angle of 45° to the line of sight.[4]

The nebula holds about 0.13 solar masses of matter, including hydrogen, helium, nitrogen, oxygen, and sulfur;[4] all with a density of less than 100 particles per cubic centimeter.[8] Its outer radius is around 0.91 ly (0.28 pc) and it is expanding with velocities in the range of 27–39 km/s into the surrounding interstellar medium.[4]

The 14th magnitude central star has since reached the turning point of its evolution where it condenses to form a white dwarf.[5][8] It has 55–60% of the Sun's mass, 41–148 times the brightness of the Sun,[4] and an effective temperature of 123,000 K.[9] The star has been successfully resolved by the Spitzer Space Telescope as a point source that does not show the infrared excess characteristic of a circumstellar disk.[10]

Messier 97, Owl Nebula
Nebula
The Owl Nebula M97 Goran Nilsson & The Liverpool Telescope
Owl Nebula
Observation data: J2000.0 epoch
Right ascension 11h 14m 47.734s[1]
Declination+55° 01′ 08.50″[1]
Distance2,030 ly (621 pc)[2]
2,800 ly (870 pc)[3] ly
Apparent magnitude (V)+9.9
Apparent dimensions (V)3′.4 × 3′.3
ConstellationUrsa Major
Physical characteristics
Radius0.91 ly (0.28 pc)[4] ly
Notable featuresOwl-like "eyes" visible through larger telescopes
DesignationsM97, NGC 3587, PN G148.4+57.0

See also

References

  1. ^ a b Kerber, F.; et al. (September 2003), "Galactic Planetary Nebulae and their central stars. I. An accurate and homogeneous set of coordinates", Astronomy and Astrophysics, 408 (3): 1029–1035, Bibcode:2003A&A...408.1029K, doi:10.1051/0004-6361:20031046.
  2. ^ a b Stanghellini, Letizia; et al. (December 2008), "The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale", The Astrophysical Journal, 689 (1): 194–202, arXiv:0807.1129, Bibcode:2008ApJ...689..194S, doi:10.1086/592395.
  3. ^ Frew, David; et al. (2016), "The Hα surface brightness-radius relation: a robust statistical distance indicator for planetary nebulae", Monthly Notices of the Royal Astronomical Society, 455 (2): 1459–1488, arXiv:1504.01534, Bibcode:2016MNRAS.455.1459F, doi:10.1093/mnras/stv1516, hdl:10722/222005.
  4. ^ a b c d e f Cuesta, L.; Phillips, J. P. (November 2000), "Excitation and Density Mapping of NGC 3587", The Astrophysical Journal, 120 (5): 2661–2669, Bibcode:2000AJ....120.2661C, doi:10.1086/316800.
  5. ^ a b Jones, Kenneth Glyn (1991), Messierś Nebulae and Star Clusters (2nd ed.), Cambridge University Press, pp. 277–279, ISBN 978-0521370790.
  6. ^ Clark, Roger Nelson (1990), Visual Astronomy of the Deep Sky, CUP Archive, ISBN 978-0521361552.
  7. ^ Per Guerrero et al. (2003), the age is 12,900 × d years, where d is the distance in kpc. According to Stanghellini et al. (2008), d is 0.621 kpc. Hence, the age is 12,900 × 0.621 ≈ 8,000 years.
  8. ^ a b c Guerrero, Martín A.; et al. (June 2003), "Physical Structure of Planetary Nebulae. I. The Owl Nebula", The Astrophysical Journal, 125 (6): 3213–3221, arXiv:astro-ph/0303056, Bibcode:2003AJ....125.3213G, doi:10.1086/375206.
  9. ^ Capriotti, Eugene R.; Kovach, William S. (March 1968), "Effective Temperatures of the Central Stars of Planetary Nebulae", Astrophysical Journal, 151 (5): 991–995, Bibcode:1968ApJ...151..991C, doi:10.1086/149498.
  10. ^ Bilíková, Jana; et al. (May 2012), "Spitzer Search for Dust Disks around Central Stars of Planetary Nebulae", The Astrophysical Journal Supplement, 200 (1): 3, Bibcode:2012ApJS..200....3B, doi:10.1088/0067-0049/200/1/3.

External links

Coordinates: Sky map 11h 14.8m 00s, +55° 01′ 00″

41P/Tuttle–Giacobini–Kresák

41P/Tuttle–Giacobini–Kresák is a periodic comet in the Solar System. The comet nucleus is estimated to be 1.4 kilometers in diameter.Discovered by Horace Parnell Tuttle on May 3, 1858, and re-discovered independently by Michel Giacobini and Ľubor Kresák in 1907 and 1951 respectively, it is a member of the Jupiter family of comets.

97 (number)

97 (ninety-seven) is the natural number following 96 and preceding 98. It is a prime number.

Aquila (constellation)

Aquila is a constellation on the celestial equator. Its name is Latin for 'eagle' and it represents the bird that carried Zeus/Jupiter's thunderbolts in Greco-Roman mythology.

Its brightest star, Altair, is one vertex of the Summer Triangle asterism. The constellation is best seen in the northern summer, as it is located along the Milky Way. Because of this location, many clusters and nebulae are found within its borders, but they are dim and galaxies are few.

List of NGC objects (3001–4000)

This is a list of NGC objects 3001–4000 from the New General Catalogue (NGC). The astronomical catalogue is composed mainly of star clusters, nebulae, and galaxies. Other objects in the catalogue can be found in the other subpages of the list of NGC objects.

The constellation information in these tables is taken from The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer, which was accessed using the "VizieR Service". Galaxy types are identified using the NASA/IPAC Extragalactic Database. The other data of these tables are from the SIMBAD Astronomical Database unless otherwise stated.

List of planetary nebulae

The following is an incomplete list of known planetary nebulae.

Messier object

The Messier objects are a set of 110 astronomical objects cataloged by the French astronomer Charles Messier in his Catalogue des Nébuleuses et des Amas d'Étoiles ("Catalogue of Nebulae and Star Clusters").

Because Messier was interested in finding only comets, he created a list of non-comet objects that frustrated his hunt for them. The compilation of this list, in collaboration with his assistant Pierre Méchain, is known as the Messier catalogue. This catalogue of objects is one of the most famous lists of astronomical objects, and many Messier objects are still referenced by their Messier number.

The catalogue includes some astronomical objects that can be observed from Earth's Northern Hemisphere such as deep-sky objects, a characteristic which makes the Messier objects extremely popular targets for amateur astronomers.A preliminary version first appeared in the Memoirs of the French Academy of Sciences in 1771,

and the last item was added in 1966 by Kenneth Glyn Jones, based on Messier's observations.

The first version of Messier's catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45 objects being Messier's.

By 1780 the catalogue had increased to 80 objects. The final version of the catalogue containing 103 objects was published in 1781 in the Connaissance des Temps for the year 1784.

However, due to what was thought for a long time to be the incorrect addition of Messier 102, the total number remained 102. Other astronomers, using side notes in Messier's texts, eventually filled out the list up to 110 objects.The catalogue consists of a diverse range of astronomical objects, ranging from star clusters and nebulae to galaxies. For example, Messier 1 is a supernova remnant, known as the Crab Nebula, and the great spiral Andromeda Galaxy is M31. Many further inclusions followed in the next century when the first addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding Messier's side note in his 1781 edition exemplar of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.

Orion Arm

The Orion Arm is a minor spiral arm of the Milky Way some 3,500 light-years (1,100 parsecs) across and approximately 10,000 light-years (3,100 parsecs) in length, containing the Solar System, including the Earth. It is also referred to by its full name, the Orion–Cygnus Arm, as well as Local Arm, Orion Bridge, and formerly, the Local Spur and Orion Spur.

The arm is named for the Orion constellation, which is one of the most prominent constellations of Northern Hemisphere winter (Southern Hemisphere summer). Some of the brightest stars and most famous celestial objects of the constellation (e.g. Betelgeuse, Rigel, the three stars of Orion's Belt, the Orion Nebula) are within it as shown on the interactive map below.

The arm is between the Carina–Sagittarius Arm (the local portions of which are toward the Galactic Center) and the Perseus Arm (the local portion of which is the main outer-most arm and one of two major arms of the galaxy).

Long thought to be a minor structure, namely a "spur" between the two arms mentioned, evidence was presented in mid 2013 that the Orion Arm might be a branch of the Perseus Arm, or possibly an independent arm segment.Within the arm, the Solar System is close to its inner rim, in a relative cavity in the arm's Interstellar Medium known as the Local Bubble, about halfway along the arm's length, approximately 8,000 parsecs (26,000 light-years) from the Galactic Center.

Pierre Méchain

Pierre François André Méchain (French pronunciation: ​[pjɛʁ fʁɑ̃swa ɑ̃dʁe meʃɛ̃]; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep sky objects and comets.

Southern Owl Nebula

The Southern Owl Nebula (PLN 283+25.1, ESO 378-1) is a planetary nebula located in the constellation Hydra. The nebula lies at a distance of 2,030 light years from Earth.

It is named so because of its resemblance to the Owl Nebula in Ursa Major. The nebula is notably symmetric, round, and has a diameter of approximately four light-years across.

Sufi Observing Competition

Sufi Observing Competition is an international competition and like Messier marathon, but more difficult with various subjects.

Since 2006, Astronomical Society of Iran – Amateur Committee (ASIAC) holds an international observing competition in the memory of Azophi. The first competition was held in 2006 in the north of Semnan Province and the 2nd SUFI observing competition was held in summer of 2008 in Ladiz near Zahedan. More than 100 observers from Iran and Iraq participated in this event.

Third Sufi Competition was held in Pasargadae, Fars province of Iran, at the enclosure of the historical tomb of Cyrus the Great on 17–20 August 2009. More than 120 amateur astronomers participated in this competition which held in 2 class of individuals and groups. Closing ceremony of 3rd Sufi Competition was held in Persepolis historical site splendidly which is in the list of UNESCO world heritage site.

Babak Amin Tafreshi, Pouria Nazemi, Kazem Kookaram and Mohammad H. Almasi are Iranian amateur astronomers who designed and manage this competition in their country until today.

Ursa Major

Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) she-bear," referring to and contrasting it with nearby Ursa Minor, the lesser bear. In antiquity, it was one of the original 48 constellations listed by Ptolemy in the 2nd century AD. Today it is the third largest of the 88 modern constellations.

Ursa Major is primarily known from the asterism of its main seven stars, which has been called the "Big Dipper," "the Wagon," "Charles's Wain," or "the Plough," among other names. In particular, the Big Dipper's stellar configuration mimics the shape of the "Little Dipper." Its two brightest stars, named Dubhe and Merak (α Ursae Majoris and β Ursae Majoris), can be used as the navigational pointer towards the place of the current northern pole star, Polaris in Ursa Minor.

Ursa Major, along with asterisms that incorporate or comprise it, is significant to numerous world cultures, often as a symbol of the north. Its depiction on the flag of Alaska is a modern example of such symbolism.

Ursa Major is visible throughout the year from most of the northern hemisphere, and appears circumpolar above the mid-northern latitudes. From southern temperate latitudes, the main asterism is invisible, but the southern parts of the constellation can still be viewed.

List
See also

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