Парсек — разлика између измена

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{{short description|Јединица за дужину која се користи у астрономији}}{{рут}}
[[Датотека:Stellarparallax parsec1.svg|десно|безоквира|306x306пискел]]
{{Infobox unit
'''Парсек''' је удаљеност са које се једна астрономска јединица ([[Астрономска јединица|АЈ]]) (на слици означена са -{a.e.}-) види под углом од једне лучне секунде. Мало стручније речено, парсек представља растојање до неког небеског тела чија је годишња [[паралакса]] једнака једној лучној секунди. Назив „парсек“ је скраћеница од '''пар'''алактичка '''сек'''унда. Посматрач са удаљене звезде би растојање Сунце-Земља видео под углом од лучне секунде ако би његова звезда била далеко тачно један парсек од Сунца.
| image = Stellarparallax parsec1.svg
| image_size = 200px
| caption = A parsec is the distance from the Sun to an [[astronomical object]] that has a [[parallax]] angle of one [[Minute and second of arc#Symbols and abbreviations|arcsecond]] (not to scale)
| standard = astronomical units
| quantity = [[length]]/[[distance]]
| symbol = pc
| units1 = [[metric system|metric]] ([[International System of Units|SI]]) units
| inunits1 = {{Val|3.0857|e=16|ul=m}} <br />&nbsp;&nbsp;&nbsp;~31 [[petametres]]
| units2 = [[Imperial units|imperial]]&nbsp;&&nbsp;[[United States customary units|US]]&nbsp;units
| inunits2 = {{Val|1.9174|e=13|ul=mi}}
| units3 = [[Astronomical system of units|astronomical units]]
| inunits3 = {{Val|2.06265|e=5|ul=au}}<br />&nbsp;&nbsp;&nbsp;{{Val|3.26156|ul=ly}}
}}
 
'''Парсек''' (симбол: '''pc''') представља [[unit of length]] used to measure the large distances to [[astronomical object]]s outside the [[Solar System]], approximately equal to {{convert|1|pc|ly|2|abbr=off|lk=out|disp=out}} or {{convert|1|pc|AU|-3|abbr=off|lk=out|disp=out}} (au), i.e. {{convert|30.9|e12km|e12mi|abbr=off|lk=on}}.{{efn|name=trillion|One trillion here is [[long and short scales|short scale]], ie. 10<sup>12</sup> (one million million, or billion in long scale).}} Parsec is obtained by the use of [[parallax]] and [[trigonometry]], and is defined as the distance at which 1 au [[subtended angle|subtends]] an angle of one [[arcsecond]]<ref>{{Cite web |title=Cosmic Distance Scales – The Milky Way |url=https://heasarc.gsfc.nasa.gov/docs/cosmic/milkyway_info.html |access-date=24 September 2014}}</ref> ({{sfrac|3600}} of a [[degree (angle)|degree]]). This corresponds to {{sfrac|{{Val|648000}}|{{pi}}}} astronomical units, i.e. <math>1\, \mathrm{pc} = 1/\tan \left({1} \ \mathrm{arcsec} \right)\, \mathrm{au}</math>.<ref name="au_parsec">{{Cite journal |last1=B. Luque |last2=F. J. Ballesteros |date=2019 |title= To the Sun and beyond |journal=[[Nature Physics]] |volume=15 |issue=12 |pages=1302 |doi=10.1038/s41567-019-0685-3 |doi-access=free}}</ref> The nearest star, [[Proxima Centauri]], is about {{convert|1.3|pc|ly|abbr=off}} from the [[Sun]].<ref>{{Cite conference |last=Benedict |first=G.&nbsp;F. |display-authors=etal |title=Astrometric Stability and Precision of Fine Guidance Sensor #3: The Parallax and Proper Motion of Proxima Centauri | url = http://clyde.as.utexas.edu/SpAstNEW/Papers_in_pdf/%7BBen93%7DEarlyProx.pdf |pages=380–384 |access-date=11 July 2007 |book-title=Proceedings of the HST Calibration Workshop}}</ref> Most [[Naked-eye stars|stars visible to the naked eye]] are within a few hundred parsecs of the Sun, with the most distant at a few thousand.<ref>{{cite web |title=Farthest Stars |url=https://stardate.org/radio/program/2021-05-15 |website=[[StarDate]] |publisher=[[University of Texas at Austin]] |access-date=5 September 2021 |date=15 May 2021}}</ref>
[[Датотека:Parsec (1).svg|400п]]
 
[[Датотека:Parsec (1).svg|400плево|мини|250п|Парсек]]
Из осенченог правоуглог троугла можемо извући релацију парсека. Позната нам је једна страница и наспрамни угао, тако да тражену страницу троугла можемо израчунати као:
 
Линија 10 ⟶ 24:
 
или
 
:<math> 1 \,\mathrm{pc} = 3,261563 \,\mathrm{sv.\, g.} = 206 264,806245 \,\mathrm{a.j.}</math>
где су употребљене ознаке за [[Светлосна година|светлосну годину]] -{sv.g.}- и за [[Астрономска јединица|астрономску јединицу]] -{a.j.}-
 
The word ''parsec'' is a [[portmanteau]] of "parallax of one second" and was coined by the British astronomer [[Herbert Hall Turner]] in 1913<ref name="dyson">{{Cite journal |last=Dyson |first=F.&nbsp;W. |author-link=Frank Watson Dyson |date=March 1913 |title= The distribution in space of the stars in Carrington's Circumpolar Catalogue |journal= [[Monthly Notices of the Royal Astronomical Society]] |volume=73 |issue=5 |page=342 <!-- the whole article is at pp.=334–345 but single page in the source that supports the content" has preference. Note that both OUP.com and Harvard.edu PDFs are truncated at p. 342 --> | bibcode=1913MNRAS..73..334D |doi=10.1093/mnras/73.5.334 |doi-access=free | quote= [''paragraph 14, page 342''] Taking the unit of distance R* to be that corresponding to a parallax of 1″·0 [… Footnote:] <br> * There is need for a name for this unit of distance. Mr. [[Carl Charlier|Charlier]] has suggested [[Sirius|Sirio]]meter, but if the violence to the Greek language can be overlooked, the word ''Astron'' might be adopted. Professor [[Herbert Hall Turner|Turner]] suggests ''Parsec'', which may be taken as an abbreviated form of "a distance corresponding to a parallax of one second".}}</ref> to make calculations of astronomical distances from only raw observational data easy for astronomers. Partly for this reason, it is the unit preferred in [[astronomy]] and [[astrophysics]], though the [[light-year]] remains prominent in [[popular science]] texts and common [[usage]]. Although parsecs are used for the shorter distances within the [[Milky Way]], multiples of parsecs are required for the larger scales in the universe, including [[kilo-|kiloparsecs]] (kpc) for the more distant objects within and around the Milky Way, [[Mega-|megaparsecs]] (Mpc) for mid-distance galaxies, and [[giga-|gigaparsecs]] (Gpc) for many [[quasar]]s and the most distant galaxies.
 
In August 2015, the [[International Astronomical Union]] (IAU) passed Resolution B2 which, as part of the definition of a standardized absolute and apparent [[bolometric magnitude]] scale, mentioned an existing explicit definition of the parsec as exactly {{sfrac|{{Val|648000}}|{{pi}}}}&nbsp;au, or approximately {{Val|3.0856775814913673|e=16}}<!-- if absurdly many digits are needed, let the full listing correspond to rounded meters -->&nbsp;metres (based on the IAU 2012 exact SI definition of the astronomical unit). This corresponds to the small-angle definition of the parsec found in many astronomical references.<ref>{{Cite book |title=Allen's Astrophysical Quantities |date=2000 |publisher=AIP Press / Springer |isbn=978-0387987460 |editor-last=Cox |editor-first=Arthur N. |edition=4th |location=New York |bibcode=2000asqu.book.....C}}</ref><ref>{{Cite book |last1=Binney |first1=James |title=Galactic Dynamics |last2=Tremaine |first2=Scott |date=2008 |publisher=Princeton University Press |isbn=978-0-691-13026-2 |edition=2nd |location=Princeton, NJ |bibcode=2008gady.book.....B}}</ref>
где су употребљене ознаке за [[Светлосна година|светлосну годину]] -{sv.g.}- и за [[Астрономска јединица|астрономску јединицу]] -{a.j.}-
 
== Историја и извођење ==
 
The parsec is defined as being equal to the length of the adjacent leg (opposite leg being 1 AU) of an extremely elongated imaginary [[right triangle]] in space. The two dimensions on which this triangle is based are its shorter leg, of length one [[astronomical unit]] (the average [[Earth]]-[[Sun]] distance), and the [[subtended|subtended angle]] of the vertex opposite that leg, measuring one [[arcsecond]]. Applying the rules of [[trigonometry]] to these two values, the unit length of the other leg of the triangle (the parsec) can be derived.
 
One of the oldest methods used by astronomers to calculate the distance to a [[star]] is to record the difference in angle between two measurements of the position of the star in the sky. The first measurement is taken from the Earth on one side of the Sun, and the second is taken approximately half a year later, when the Earth is on the opposite side of the Sun. The distance between the two positions of the Earth when the two measurements were taken is twice the distance between the Earth and the Sun. The difference in angle between the two measurements is twice the parallax angle, which is formed by lines from the Sun and Earth to the star at the distant [[Vertex (geometry)#Of an angle|vertex]]. Then the distance to the star could be calculated using trigonometry.<ref name="NASAparallax">{{Cite web |title=Deriving the Parallax Formula |url=http://imagine.gsfc.nasa.gov/YBA/HTCas-size/parallax1-derive.html |last=[[High Energy Astrophysics Science Archive Research Center]] (HEASARC) |website=NASA's Imagine the Universe! |publisher=Astrophysics Science Division (ASD) at [[NASA]]'s [[Goddard Space Flight Center]] |access-date=26 November 2011}}</ref> The first successful published direct measurements of an object at interstellar distances were undertaken by German astronomer [[Friedrich Wilhelm Bessel]] in 1838, who used this approach to calculate the 3.5-parsec distance of [[61 Cygni]].<ref>{{Cite journal |last=Bessel |first=F.&nbsp;W. |author-link=Friedrich Wilhelm Bessel |date=1838 |title=Bestimmung der Entfernung des 61sten Sterns des Schwans |trans-title=Determination of the distance of the 61st star of Cygnus |url=http://www.ari.uni-heidelberg.de/gaia/documents/bessel-1838/index.html |url-status=dead |journal=[[Astronomische Nachrichten]] |volume=16 |issue=5 |pages=65–96 |bibcode=1838AN.....16...65B |doi=10.1002/asna.18390160502 |archive-url=https://web.archive.org/web/20070624220502/http://www.ari.uni-heidelberg.de/gaia/documents/bessel-1838/index.html |archive-date=24 June 2007}}</ref>
 
== Раздаљине у парсецима ==
Линија 31 ⟶ 52:
* [[Светлосна година]]
* [[Паралакса]]
 
== Напомене ==
{{notes}}
 
== Референце ==
{{reflist}}
 
== Литература ==
{{refbegin|30em}}
* {{cite book|url=https://books.google.com/books?id=JARaN7Jmm9cC&pg=PA184|title=The Sky is Your Laboratory|isbn=978-0-387-73995-3|last1=Buchheim|first1=Robert|date=4 October 2007}}
* Bessel, FW, "[http://www.ari.uni-heidelberg.de/gaia/documents/bessel-1838/index.html Bestimmung der Entfernung des 61sten Sterns des Schwans] {{webarchive|url=https://web.archive.org/web/20070624220502/http://www.ari.uni-heidelberg.de/gaia/documents/bessel-1838/index.html |date=2007-06-24 }}" (1838) ''[[Astronomische Nachrichten]]'', vol.&nbsp;16, pp.&nbsp;65–96.
* {{Cite journal|last=Habison|first=Peter|date=1998|title=Astrometry and early astrophysics at Kuffner Observatory in the late 19th century|journal=Acta Historica Astronomiae|volume=3|pages=93–94|bibcode=1998AcHA....3...93H|issn=0003-2670}}
* {{cite web |last1=Harrington |first1=J.D. |last2=Villard |first2=Ray |title=NASA's Hubble Extends Stellar Tape Measure 10 Times Farther into Space |url=http://www.nasa.gov/press/2014/april/nasas-hubble-extends-stellar-tape-measure-10-times-farther-into-space |date=10 April 2014 |work=[[NASA]] |access-date=17 October 2014 }}
* {{cite journal |title=Parallax Beyond a Kiloparsec from Spatially Scanning the Wide Field Camera 3 on the Hubble Space Telescope |author-link1= Adam Riess |first1=Adam G.|last1=Riess |first2=Stefano|last2= Casertano |first3=Jay|last3= Anderson |first4=John|last4=Mackenty |first5=Alexei V.|last5=Filippenko |arxiv=1401.0484 |year= 2014|doi=10.1088/0004-637X/785/2/161|volume=785|issue= 2 |journal=The Astrophysical Journal|page=161|bibcode=2014ApJ...785..161R }}
* {{Cite web|last=Talbert|first=Tricia|date=2020-06-10|title=New Horizons Conducts the First Interstellar Parallax Experiment|url=http://www.nasa.gov/feature/nasa-s-new-horizons-conducts-the-first-interstellar-parallax-experiment|access-date=2021-05-20|website=NASA}}
* {{cite web | last = Henney | first = Paul J. | title = ESA's Gaia Mission to study stars | publisher = Astronomy Today | url = http://www.astronomytoday.com/exploration/gaia.html | access-date = 8 March 2008}}
* {{cite journal | last=Popowski | first=Piotr | author2=Gould, Andrew | date=29 January 1998 | title=Mathematics of Statistical Parallax and the Local Distance Scale | url=https://archive.org/details/arxiv-astro-ph9703140 | arxiv=astro-ph/9703140 | bibcode=1997astro.ph..3140P }}
* {{cite journal|doi=10.1086/118167|bibcode=1996AJ....112.2110L|arxiv=astro-ph/9608108|title=The Absolute Magnitude and Kinematics of RR Lyrae Stars Via Statistical Parallax|journal=The Astronomical Journal|volume=112|pages=2110|year=1996 |last1=Layden|first1=Andrew C|last2=Hanson|first2=Robert B|last3=Hawley|first3=Suzanne L|last4=Klemola|first4=Arnold R|last5=Hanley|first5=Christopher J}}
* {{cite book | last=Hirshfeld | first=Alan w. | title=Parallax: The Race to Measure the Cosmos | location=New York | publisher=W. H. Freeman | date=2001 | isbn=0-7167-3711-6 | url-access=registration | url=https://archive.org/details/parallax00alan }}
* {{cite book | last=Whipple | first=Fred L. | date=2007 | title=Earth Moon and Planets | isbn=978-1-4067-6413-0 | publisher=Read Books }}.
* {{cite book | last=Zeilik | first=Michael A. | last2=Gregory | first2=Stephan A. | title=Introductory Astronomy & Astrophysics | edition=4th | date=1998 | publisher=Saunders College Publishing | isbn=0-03-006228-4 }}.
* {{cite journal|author1=Dyson, F. W.|title=Measurement of the distances of the stars|journal=The Observatory|volume=38|pages=292|year=1915|bibcode=1915Obs....38..292D}}
* {{cite journal |last1=Ash |first1=M. E. |last2=Shapiro |first2=I. I. |last3=Smith |first3=W. B. |year=1967 |title=Astronomical constants and planetary ephemerides deduced from radar and optical observations |journal=[[The Astronomical Journal]] |volume=72 |pages=338 |bibcode=1967AJ.....72..338A |doi=10.1086/110230}}
* {{cite journal | last=Perryman | first=M. A. C. | year=1999 | display-authors=etal | title=The HIPPARCOS Catalogue | journal=[[Astronomy and Astrophysics]] | volume=323 | pages=L49–L52 | bibcode=1997A&A...323L..49P }}
* {{cite web |last1=Harrington |first1=J. D. |last2=Villard |first2=R. |date=10 April 2014 |title=NASA's Hubble Extends Stellar Tape Measure 10 Times Farther Into Space |url=http://www.nasa.gov/press/2014/april/nasas-hubble-extends-stellar-tape-measure-10-times-farther-into-space |publisher=[[NASA]] |access-date=17 October 2014 |archive-date=17 February 2019 |archive-url=https://web.archive.org/web/20190217091521/https://www.nasa.gov/press/2014/april/nasas-hubble-extends-stellar-tape-measure-10-times-farther-into-space/ |url-status=live }}
* {{cite journal |last1=Riess |first1=A. G. |last2=Casertano |first2=S. |last3=Anderson |first3=J. |last4=MacKenty |first4=J. |last5=Filippenko |first5=A. V. |year=2014 |title=Parallax Beyond a Kiloparsec from Spatially Scanning the Wide Field Camera 3 on the Hubble Space Telescope |journal=[[The Astrophysical Journal]] |volume=785 |issue=2 |pages=161 |arxiv=1401.0484 |bibcode=2014ApJ...785..161R |doi=10.1088/0004-637X/785/2/161 |s2cid=55928992 }}
* {{cite book | first=Baidyanath | last=B. | year=2003 | title=An Introduction to Astrophysics | publisher=PHI Learning Private Limited | isbn=978-81-203-1121-3 }}
* {{cite web |title=Hubble finds Universe may be expanding faster than expected |url=http://www.spacetelescope.org/news/heic1611/ |access-date=3 June 2016 |archive-date=11 September 2018 |archive-url=https://web.archive.org/web/20180911191706/https://www.spacetelescope.org/news/heic1611/ |url-status=live }}
 
{{refend}}
 
== Спољашње везе ==
{{Commons category|Parsec}}
* {{Cite web |title=Astronomical Distance Scales |url=http://csep10.phys.utk.edu/guidry/violence/distances.html |last=Guidry |first=Michael |website=Astronomy 162: Stars, Galaxies, and Cosmology |publisher=University of Tennessee, Knoxville |url-status=dead |archive-url=https://archive.today/20121212134512/http://csep10.phys.utk.edu/guidry/violence/distances.html |archive-date=12 December 2012 |access-date=26 March 2010}}
* {{Cite web |title=pc Parsec |url=http://www.sixtysymbols.com/videos/parsec.htm |last=Merrifield |first=Michael |website=Sixty Symbols |publisher=[[Brady Haran]] for the [[University of Nottingham]]}}
 
{{нормативна контрола}}
Преузето из „https://sr.wikipedia.org/wiki/Парсек