| 词条 | Owl Nebula |
| 释义 |
| name = Messier 97, Owl Nebula | image = The Owl Nebula M97 Goran Nilsson & The Liverpool Telescope.jpg | caption = Owl Nebula | type = 3a | epoch = J2000.0 | ra = {{RA|11|14|47.734}}[1] | dec = {{DEC|+55|01|08.50}}[1] | dist_ly = {{Convert|621|pc|ly|abbr=on|lk=on|disp=flip}}[3] {{Convert|870|pc|ly|abbr=on|lk=on|disp=flip}}[4] | appmag_v = +9.9 | size_v = {{nowrap|3′.4 × 3′.3}} | constellation = Ursa Major | radius_ly = {{Convert|0.28|pc|ly|abbr=on|disp=flip}}[5] | absmag_v = | notes = Owl-like "eyes" visible through larger telescopes | names = M97, NGC 3587, PN G148.4+57.0 }} 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.[3] It was discovered by French astronomer Pierre Méchain on February 16, 1781. 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.[8] The nebula is approximately 8,000 years old. 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.[5] The nebula is arranged in three concentric shells, with the outermost shell being about 20–30% larger than the inner shell.[11] 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.[5] The nebula holds about 0.13 solar masses of matter, including hydrogen, helium, nitrogen, oxygen, and sulfur;[5] all with a density of less than 100 particles per cubic centimeter.[11] Its outer radius is around {{Convert|0.28|pc|ly|abbr=on|disp=flip}} and it is expanding with velocities in the range of 27–39 km/s into the surrounding interstellar medium.[5] The 14th magnitude central star has since reached the turning point of its evolution where it condenses to form a white dwarf.[11] It has 55–60% of the Sun's mass, 41–148 times the brightness of the Sun,[5] and an effective temperature of 123,000 K.[19] 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.[20] See also
References1. ^1 {{Citation | last1 = Clark | first1 = Roger Nelson | title = Visual Astronomy of the Deep Sky | publisher = CUP Archive | date = 1990 | isbn = 978-0521361552 | url = https://books.google.com/books?id=gCI9AAAAIAAJ&pg=PA133 | postscript= .}} [1][2][3][4][5][6][7][8]2. ^1 2 {{Citation | last1 = Kerber | first1 = F. | last2 = Mignani | first2 = R. P. | last3 = Guglielmetti | first3 = F. | last4 = Wicenec | first14 = A. | display-authors = 1 | title = Galactic Planetary Nebulae and their central stars. I. An accurate and homogeneous set of coordinates | journal = Astronomy and Astrophysics | volume = 408 | issue = 3 | pages = 1029–1035 |date=September 2003 | doi = 10.1051/0004-6361:20031046 | bibcode = 2003A&A...408.1029K | postscript= .}} 3. ^1 2 {{Citation | last1 = Stanghellini | first1 = Letizia | last2 = Shaw | first2 = Richard A. | last3 = Villaver | first3 = Eva | display-authors = 1 | title = The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale | journal = The Astrophysical Journal | volume = 689 | issue = 1 | pages = 194–202 |date=December 2008 | doi = 10.1086/592395 | postscript= .|arxiv = 0807.1129 |bibcode = 2008ApJ...689..194S }} 4. ^1 {{Citation | last1 = Frew | first1 = David | last2 = Parker | first2 = Quentin A. | last3 = Bojcic | first3 = Ivan | display-authors = 1 | title = The Hα surface brightness-radius relation: a robust statistical distance indicator for planetary nebulae | journal = Monthly Notices of the Royal Astronomical Society | volume = 455 | issue = 2 | pages = 1459–1488 |year=2016 | doi = 10.1093/mnras/stv1516 | postscript= .|arxiv =1504.01534 |bibcode = 2016MNRAS.455.1459F | hdl= 10722/222005 }} 5. ^1 2 3 {{Citation | last1 = Guerrero | first1 = Martín A. | last2 = Chu | first2 = You-Hua | last3 = Manchado | first3 = Arturo | last4 = Kwitter | first4 = Karen B. | display-authors = 1 | title = Physical Structure of Planetary Nebulae. I. The Owl Nebula | journal = The Astrophysical Journal | volume = 125 | issue = 6 | pages = 3213–3221 |date=June 2003 | doi = 10.1086/375206 | bibcode = 2003AJ....125.3213G | arxiv = astro-ph/0303056 | postscript= .}} 6. ^1 {{Citation | last1 = Capriotti | first1 = Eugene R. | last2 = Kovach | first2 = William S. | title = Effective Temperatures of the Central Stars of Planetary Nebulae | journal = Astrophysical Journal | volume = 151 | issue = 5 | pages = 991–995 |date=March 1968 | doi = 10.1086/149498 | bibcode = 1968ApJ...151..991C | postscript= .}} 7. ^1 2 3 4 5 6 {{Citation | last1 = Cuesta | first1 = L. | last2 = Phillips | first2 = J. P. | title = Excitation and Density Mapping of NGC 3587 | journal = The Astrophysical Journal | volume = 120 | issue = 5 | pages = 2661–2669 |date=November 2000 | doi = 10.1086/316800 | bibcode = 2000AJ....120.2661C | postscript= .}} 8. ^1 {{Citation | last1 = Bilíková | first1 = Jana | last2 = Chu | first2 = You-Hua | last3 = Gruendl | first3 = Robert A. | last4 = Su | first4 = Kate Y. L. | last5 = De Marco | first5 = Orsola | display-authors = 1 | title = Spitzer Search for Dust Disks around Central Stars of Planetary Nebulae | journal = The Astrophysical Journal Supplement | volume = 200 | issue = 1 | pages = 3 |date=May 2012 | doi = 10.1088/0067-0049/200/1/3 | bibcode = 2012ApJS..200....3B | postscript= .}} }} External links
6 : Messier objects|NGC objects|Planetary nebulae|Ursa Major (constellation)|Astronomical objects discovered in 1781|Discoveries by Pierre Méchain |
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