View source for NGC 6530

{{Short description|Open cluster in the constellation Sagittarius}}
{{Infobox open cluster
 | name      = {{PAGENAME}}
 | image     = M8_rvb.jpg
 | caption   = NGC 6530 (right) and the Lagoon Nebula
 | credit    = <!-- Per MOS:CREDITS, credits are discouraged -->
 | epoch     = [[J2000]]
 | constellation = [[Sagittarius (constellation)|Sagittarius]]
 | ra        = {{RA|18|04|31.''0''}}<ref name=Wu_et_al_2009/>
 | dec       = {{DEC|−24|21|3''0''}}<ref name=Wu_et_al_2009/>
 | dist_ly   = {{cvt|1336|pc|ly|disp=out|lk=on}}&nbsp;({{val|1336|76|68|ul=pc|fmt=commas}})<ref name=Kuhn_et_al_2018/><br>{{cvt|1325|pc|ly|order=flip|lk=off}}<ref name=Damiani_et_al_2019/>
 | dist_pc   = 
 | appmag_v  = 4.6<ref>{{cite web |url=https://www.messier.seds.org/xtra/ngc/n6530.html |title=NGC 6530 |access-date=27 April 2022 |website=SEDS NGC Catalog |archive-date=27 September 2021 |archive-url=https://web.archive.org/web/20210927163735/http://www.messier.seds.org/xtra/ngc/n6530.html |url-status=dead }}</ref>
 | size_v    = {{val|14.0|ul=arcminute}}<ref name=Morales_et_al_2013/>
 | radius_ly = {{val|7|u=ly}}<ref name=Consolmagno_Davis_2019/>
 | mass_msol = <!-- Cluster mass in solar masses: {{val|#.##|ul=solar mass}} -->
 | age       = 4–6&nbsp;Myr<ref name=Aidelman_et_al_2018/>
 | notes     = H II region
 | names     = [[Collinder catalogue|Cr]] 362
}}

'''NGC 6530''' is a young<ref name=Topasna_et_al_2020/> [[open cluster]] of stars in the southern [[constellation]] of [[Sagittarius (constellation)|Sagittarius]], located some 4,300&nbsp;[[light year]]s from the [[Sun]].<ref name=Damiani_et_al_2019/> It exists within the [[H II region]] known as the [[Lagoon Nebula]], or Messier 8,<ref name=Prisinzano_et_al_2019/> and spans an [[angular diameter]] of {{val|14.0|ul=arcminute}}.<ref name=Morales_et_al_2013/> The [[nebula|nebulosity]] was first discovered by [[Giovanni Battista Hodierna|G. B. Hodierna]] prior to 1654, then re-discovered by [[John Flamsteed|J. Flamsteed]] circa 1680. It was [[Jean-Philippe Loys de Cheseaux|P. Loys]] who classified it as a cluster in 1746, as he could only resolve stars. The following year, [[Guillaume Le Gentil|G. Le Gentil]] determined it was both a nebula and a cluster.<ref name=Chen2015/>

[[File:Hubble NGC6530.jpg|thumb|left|Portion of NGC 6530 seen by [[Hubble Space Telescope|Hubble]]]]

The brightest six members of the cluster are visible in 10×50 binoculars at magnitudes 6.9 and fainter, while fifteen evenly distributed stars are visible with a 25×100 pair.<ref name=Crossen_Rhemann_2012/> More than two dozen stars are visible in an amateur telescope.<ref name=Consolmagno_Davis_2019/> The average [[Extinction (astronomy)|extinction]] ''A<sub>V</sub>'' due to [[interstellar dust]] along the line of sight from the Earth is {{val|1.20|0.24}}, with a color excess ''{{nowrap|E(B−V)}}'' of {{val|0.38|0.07}}.<ref name=Topasna_et_al_2020/>

In total, 3,675 stars in the field of NGC 6530 have been catalogued as candidate members, with the likely members being 2,728.<ref name=Damiani_et_al_2019/> As of 2019, 652 stars have been confirmed as members: 333 of these are classical [[T Tauri star|T Tauri]]-type [[variable star]]s showing a [[near infrared]] [[infrared excess|emission excess]], while the remainder are weak T Tauri stars showing a photospheric excess.<ref name=Prisinzano_et_al_2019/> Candidate stars appear in two main groups at the cluster core and the Sagittarius "Hourglass nebula", with other smaller concentrations. Two such minor concentrations are associated with the stars [[7 Sagittarii|7 Sgr]] and HD 164536.<ref name=Damiani_et_al_2019/>

Age estimates for the members shows a spread in values that suggests more than one burst of [[star formation]]. Initial star formation began up to 15 million years ago, but the bulk formed in the last 1–2&nbsp;million years near the cluster center.<ref name=Prisinzano_et_al_2019/> [[Astrometry|Astrometric]] data suggests the parent [[molecular cloud]] collided with the [[galactic plane]] some four million years ago, which may have triggered the star formation.<ref name=Damiani_et_al_2019/> The dispersion of velocities for a sample of stars in the cluster suggests it may be [[Gravitationally bound|gravitationally unbound]] and there is evidence the star population is expanding, particularly to the north and south.<ref name=Wright_et_al_2019/>

==References==
{{reflist|refs=

<ref name=Consolmagno_Davis_2019>{{cite book
 | title=Turn Left at Orion: Hundreds of Night Sky Objects to See in a Home Telescope – and How to Find Them
 | first1=Guy | last1=Consolmagno | first2=Dan M. | last2=Davis
 | year=2019 | page=147 | isbn=9781108457569
 | publisher=Cambridge University Press
 | url=https://books.google.com/books?id=D2JjDwAAQBAJ&pg=PA147 }}</ref>

<ref name=Chen2015>{{cite book
 | title=A Guide to Hubble Space Telescope Objects, Their Selection, Location, and Significance
 | first1=James L. | last1=Chen | first2=Adam | last2=Chen
 | date=2015 | page=67 | isbn=9783319188720
 | publisher=Springer International Publishing
 | url=https://books.google.com/books?id=qj0wCgAAQBAJ&pg=PA67 }}</ref>

<ref name=Aidelman_et_al_2018>{{cite journal
 | title=Open clusters. III. Fundamental parameters of B stars in NGC 6087, NGC 6250, NGC 6383, and NGC 6530 B-type stars with circumstellar envelopes
 | last1=Aidelman | first1=Y. | last2=Cidale | first2=L. S.
 | last3=Zorec | first3=J. | last4=Panei | first4=J. A.
 | display-authors=1 | journal=Astronomy & Astrophysics
 | volume=610 | id=A30 | pages=18
 | date=February 2018 | doi=10.1051/0004-6361/201730995
 | arxiv=1711.01311 | bibcode=2018A&A...610A..30A | s2cid=59375851 }}</ref>

<ref name=Morales_et_al_2013>{{cite journal
 | title=Stellar clusters in the inner Galaxy and their correlation with cold dust emission
 | last1=Morales | first1=Esteban F. E. | last2=Wyrowski | first2=Friedrich
 | last3=Schuller | first3=Frederic | last4=Menten | first4=Karl M.
 | display-authors=1 | journal=Astronomy & Astrophysics
 | volume=560 | pages=A76 | year=2013
 | doi=10.1051/0004-6361/201321626 | arxiv=1310.2612
 | bibcode = 2013A&A...560A..76M | s2cid=118422539 }}</ref>

<ref name=Crossen_Rhemann_2012>{{cite book
 | title=Sky Vistas, Astronomy for Binoculars and Richest-Field Telescopes
 | first1=Craig | last1=Crossen | first2=Gerald | last2=Rhemann
 | date=2012 | page=46 | isbn=9783709106266
 | publisher=Springer Vienna
 | url=https://books.google.com/books?id=3vELBwAAQBAJ&pg=PA46 }}</ref>

<ref name=Wright_et_al_2019>{{cite journal
 | title=The Gaia-ESO Survey: asymmetric expansion of the Lagoon Nebula cluster NGC 6530 from GES and Gaia DR2
 | last1=Wright | first1=Nicholas J. | last2=Jeffries | first2=R. D.
 | last3=Jackson | first3=R. J. | last4=Bayo | first4=A.
 | last5=Bonito | first5=R. | last6=Damiani | first6=F.
 | last7=Kalari | first7=V. | last8=Lanzafame | first8=A. C.
 | last9=Pancino | first9=E. | last10=Parker | first10=R. J.
 | last11=Prisinzano | first11=L. | last12=Randich | first12=S.
 | last13=Vink | first13=J. S. | last14=Alfaro | first14=E. J.
 | last15=Bergemann | first15=M. | last16=Franciosini | first16=E.
 | last17=Gilmore | first17=G. | last18=Gonneau | first18=A.
 | last19=Hourihane | first19=A. | last20=Jofré | first20=P.
 | last21=Koposov | first21=S. E. | last22=Lewis | first22=J.
 | last23=Magrini | first23=L. | last24=Micela | first24=G.
 | last25=Morbidelli | first25=L. | last26=Sacco | first26=G. G.
 | last27=Worley | first27=C. C. | last28=Zaggia | first28=S.
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=486 | issue=2 | pages=2477–2493 | display-authors=1
 | date=June 2019 | doi=10.1093/mnras/stz870
 | doi-access=free | arxiv=1903.12176 | bibcode=2019MNRAS.486.2477W }}</ref>

<ref name=Prisinzano_et_al_2019>{{cite journal
 | title=The Gaia-ESO Survey: Age spread in the star forming region NGC 6530 from the HR diagram and gravity indicators
 | last1=Prisinzano | first1=L. | last2=Damiani | first2=F.
 | last3=Kalari | first3=V. | last4=Jeffries | first4=R.
 | last5=Bonito | first5=R. | last6=Micela | first6=G.
 | last7=Wright | first7=N. J. | last8=Jackson | first8=R. J.
 | last9=Tognelli | first9=E. | last10=Guarcello | first10=M. G.
 | last11=Vink | first11=J. S. | last12=Klutsch | first12=A.
 | last13=Jiménez-Esteban | first13=F. M. | last14=Roccatagliata | first14=V.
 | last15=Tautvaišienė | first15=G. | last16=Gilmore | first16=G.
 | last17=Randich | first17=S. | last18=Alfaro | first18=E. J.
 | last19=Flaccomio | first19=E. | last20=Koposov | first20=S.
 | last21=Lanzafame | first21=A. | last22=Pancino | first22=E.
 | last23=Bergemann | first23=M. | last24=Carraro | first24=G.
 | last25=Franciosini | first25=E. | last26=Frasca | first26=A.
 | last27=Gonneau | first27=A. | last28=Hourihane | first28=A.
 | last29=Jofré | first29=P. | last30=Lewis | first30=J.
 | last31=Magrini | first31=L. | last32=Monaco | first32=L.
 | last33=Morbidelli | first33=L. | last34=Sacco | first34=G. G.
 | last35=Worley | first35=C. C. | last36=Zaggia | first36=S.
 | display-authors=1 | journal=Astronomy & Astrophysics
 | volume=623 | id=A159 | pages=22
 | date=March 2019 | doi=10.1051/0004-6361/201834870
 | arxiv=1901.09589 | bibcode=2019A&A...623A.159P | s2cid=119394685 }}</ref>

<ref name=Damiani_et_al_2019>{{cite journal
 | title=Wide-area photometric and astrometric (Gaia DR2) study of the young cluster NGC 6530
 | last1=Damiani | first1=F. | last2=Prisinzano | first2=L.
 | last3=Micela | first3=G. | last4=Sciortino | first4=S.
 | display-authors=1 | journal=Astronomy & Astrophysics
 | volume=623 | id=A25 | pages=21
 | date=March 2019 | doi=10.1051/0004-6361/201833877
 | arxiv=1812.11402 | bibcode=2019A&A...623A..25D | s2cid=119428764 }}</ref>

<ref name=Topasna_et_al_2020>{{cite journal
 | title=Interstellar Extinction in the Direction of the Young Open Cluster NGC 6530
 | display-authors=1 | last1=Topasna | first1=G. A.
 | last2=Jones | first2=R. H. | last3=Kaltcheva | first3=N. T.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=132 | issue=1010 | id=044301 | pages=14 | date=February 2020
 | doi=10.1088/1538-3873/ab6aba | bibcode=2020PASP..132d4301T | doi-access=free }}</ref>

<ref name=Wu_et_al_2009>{{Cite journal
 | title=The orbits of open clusters in the Galaxy
 | last1=Wu | first1=Zhen-Yu | last2=Zhou | first2=Xu
 | last3=Ma | first3=Jun | last4=Du | first4=Cui-Hua
 | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=399 | issue=4 | pages=2146–2164 | date=November 2009
 | arxiv=0909.3737 | bibcode=2009MNRAS.399.2146W
 | doi=10.1111/j.1365-2966.2009.15416.x | doi-access=free | s2cid=6066790 }}</ref>

<ref name=Kuhn_et_al_2018>{{cite journal
 | title= Kinematics in Young Star Clusters and Associations with Gaia DR2
 | display-authors=1 | last1=Kuhn | first1=Michael A.
 | last2=Hillenbrand | first2=Lynne A. | last3=Sills | first3=Alison
 | last4=Feigelson | first4=Eric D. | last5=Getman | first5=Konstantin V.
 | journal=The Astrophysical Journal
 | volume=870 | issue=1 | pages=32| year=2018
 | arxiv=1807.02115 | bibcode=2019ApJ...870...32K
 | doi=10.3847/1538-4357/aaef8c | s2cid=119328315 | doi-access=free }}</ref>

}}

==External links==
* {{cite news
 | title=Astronomers investigate open cluster NGC 6530
 | first=Tomasz | last=Nowakowski
 | website=phys.org
 | url=https://phys.org/news/2019-01-astronomers-cluster-ngc.html
 | access-date=2021-01-03 }}
* {{cite simbad | title=NGC 6530 | access-date=2022-01-03 }}

{{Stars of Sagittarius}}
{{Ngc70}}

[[Category:Open clusters|NGC 6530]]
[[Category:Sagittarius (constellation)|NGC 6530]]
[[Category:NGC objects|6530]]

[[sk:Lagúna (hmlovina)#Centrálna hviezdokopa]]