Carina–Sagittarius Arm: Difference between revisions

Browse history interactively

← Previous edit

Content deleted Content added

VisualWikitext

Revision as of 23:03, 30 October 2007 edit Michael Devore (talk \| contribs) Extended confirmed users, Pending changes reviewers, Rollbackers 36,199 edits good stub info, well-improved in context and content since Aug 06 tagging; removing cleanup tag, revert with reasons if major concerns remain ← Previous edit		Latest revision as of 01:47, 13 June 2024 edit undo Citation bot (talk \| contribs) Bots 5,256,394 edits Added issue. Removed parameters. \| Use this bot. Report bugs. \| Suggested by Abductive \| Category:Milky Way arms \| #UCB_Category 2/7
(105 intermediate revisions by 80 users not shown)
Line 1: {{short description\|Minor spiral arm of the Milky Way Galaxy and one of its most pronounced arms}} [[Image:~~Milky_Way_Spiral_Arm~~Milky Way Arms ssc2008-10.svg\|~~250px~~500px\|right\|thumb\|Observed structure of the [[Milky Way]]'s spiral arms]] The '''~~Sagittarius~~Carina–Sagittarius Arm''' (also known as the '''Sagittarius~~-Carina~~ Arm'';' or '''Sagittarius–Carina Arm''', labeled '''-I'''{{clarify\|date=April 2023\|reason=What is this "-I" label meant to indicate?}}) is ~~one~~generally ofthought ~~the~~to be a minor [[spiral arm]]s of ~~our home~~the [[~~galaxy~~Milky Way]]~~, the~~ [[~~Milky Way~~galaxy]].<ref name=Churchwell2009/> Each spiral arm is a long, diffuse curving streamer of [[~~stars~~star]]s that radiates ~~out~~ from the [[~~galactic~~Galactic ~~center~~Center]]. These gigantic structures are often composed of billions of stars, and ~~Sagittarius~~thousands of gas clouds. The Carina–Sagittarius Arm is one of the ~~largest~~most pronounced arms in our galaxy as many [[HII region]]s, young stars and [[giant molecular cloud]]s are concentrated in it.<ref name="▼ Steiman-Cameron2010">{{Cite journal \| last1 = Steiman-Cameron \| first1 = T. Y. \| last2 = Wolfire \| first2 = M. \| last3 = Hollenbach \| first3 = D. \| title = Cobeand the Galactic Interstellar Medium: Geometry of the Spiral Arms from Fir Cooling Lines \| journal = The Astrophysical Journal \| volume = 722 \| issue = 2 \| pages = 1460 \| year = 2010 \| doi = 10.1088/0004-637X/722/2/1460\| bibcode=2010ApJ...722.1460S\| doi-access = free }}</ref> The Milky Way is a [[barred spiral galaxy]], consisting of a central crossbar and bulge from which two major and several minor spiral arms radiate outwards. This arm lies between two major spiral arms, the [[Scutum–Centaurus Arm]], the near part of which is visible looking ''inward'', i.e. toward the Galactic Center with the rest beyond the galactic central bulge, and the [[Perseus Arm]], similar in size and shape but locally much closer looking outward, away from the bright, immediately obvious extent of the Milky Way in a perfect observational sky.<ref name=Churchwell2009>{{cite journal\|last=Churchwell\|first=Ed\|author2=Babler, Brian L. \|author3=Meade, Marlin A. \|title=The Spitzer/GLIMPSE Surveys: A New View of the Milky Way\|journal=Publications of the Astronomical Society of the Pacific\|year=2009\|volume=121\|issue=877 \|pages=213–230\|doi=10.1086/597811\|url=http://www.astro.wisc.edu/sirtf/Churchwell_2009.pdf\|bibcode=2009PASP..121..213C}}</ref> It is named for its proximity to the [[Sagittarius (constellation)\|Sagittarius]] and [[Carina (constellation)\|Carina]] constellations as seen in the [[night sky]] from Earth, in the direction of the [[Galactic Center]]. ▲The '''Sagittarius Arm''' (also known as ''Sagittarius-Carina Arm''; labeled "-I") is one of the [[spiral arm]]s of our home [[galaxy]], the [[Milky Way]]. Each spiral arm is a long, diffuse curving streamer of [[stars]] that radiates out from the [[galactic center]]. These gigantic structures are often composed of billions of stars, and Sagittarius is one of the largest arms in our galaxy. The arm dissipates near its middle, shortly after reaching its maximal angle, viewed from the Solar System, from the Galactic Center of about 80°. Extending from the galaxy's central bar is the '''Sagittarius Arm''' (Sagittarius bar). Beyond the dissipated zone it is the '''Carina Arm'''.<ref name=Churchwell2009/> The Milky Way is a [[barred spiral galaxy]], consisting of a central crossbar from which several spiral arms radiate outwards. The Sagittarius Arm's innermost end connects to one of the ends of this central bar, making it one of the two major spiral arms of the galaxy. The other large arm is the [[Cygnus Arm]]. ==Geometry== The dense, inner arm of Sagittarius is located between the [[Scutum-Crux Arm]] and the [[Orion Arm]] (the Orion arm is marked as the Local Spur on the galactic map, and Orion also contains our sun). It is named for its proximity to the [[Sagittarius (constellation)\|Sagittarius]] constellation as seen in the [[night sky]] from Earth, in the direction of the [[galactic center]]. A study was done with the measured parallaxes and motions of 10 regions in the Sagittarius arm where massive stars are formed. Data was gathered using the BeSSeL Survey with the [[Very Long Baseline Array\|VLBA]], and the results were synthesized to discover the physical properties of these sections (called the Galactocentric azimuth, around −2 and 65 degrees). The results were that the spiral pitch angle of the arms is 7.3 [[Plus–minus sign\|±]] 1.5 degrees, and the half-width of the arms of the Milky Way were found to be 0.2 kpc. The nearest part to the Sun is around 1.4 ± 0.2 kpc away.<ref>{{cite journal \|last1=Wu \|first1=Y. \|last2=Sato \|first2=M. \|last3=Zheng \|first3=X. \|title=Trigonometric parallaxes of star forming regions in the Sagittarius spiral arm \|journal=[[Astronomy & Astrophysics]] \|year=2014 \|volume=566 \|pages=A17 \|doi=10.1051/0004-6361/201322765 \|display-authors=etal \|arxiv=1404.4683 \|bibcode=2014A&A...566A..17W \|s2cid=118592025}}</ref> ==Minor arm== ~~The Sagittarius Arm is divided into two parts. Curving outward from the galaxy's central bar is the Sagittarius Arm (Sagittarius bar), which further outward becomes the Carina arm.~~ In 2008, infrared observations with the [[Spitzer Space Telescope]] showed that the Carina–Sagittarius Arm has a relative paucity of young stars, in contrast with the [[Scutum-Centaurus Arm]] and [[Perseus Arm]]. This suggests that the Carina–Sagittarius Arm is a minor arm, along with the [[Norma Arm]] (Outer Arm). These two appear to be mostly concentrations of gas, sparsely sprinkled with pockets of newly formed stars.<ref name=Churchwell2009/><ref>{{cite news \|first=David \|last=Shiga \|title=Two of the Milky Way's spiral arms may be 'demoted' \|url=https://www.newscientist.com/article/dn14057-two-of-the-milky-ways-spiral-arms-may-be-demoted.html \|work=NewScientist \|date=2008-06-03 \|access-date=2009-09-08 }}</ref> ==Visible objects== ~~<div style="clear: both"></div>~~ [[File:Milky Way Sagittarius Arm.jpg\|In front of, above and below the Galactic Center much visible dust appears from the Scutum-Centaurus Arm, some dust and nebulae in the Sagittarius Arm and many stars and objects from our own arm.\|thumb]] A number of [[Messier ~~objects~~object]],s ~~objects~~and ~~that~~other ~~are~~objects visible through an amateur's telescope or binoculars, are found in the Sagittarius Arm. (here listed approximately in order from east to west along the arm):▼ [[Wild Duck Cluster\|M11, the Wild Duck Cluster]] in [[Scutum (constellation)\|Scutum]] ([[Right ascension\|RA]] 18h 51m)▼ [[Open Cluster M26]] in Scutum (RA 18h 45m)▼ [[Eagle Nebula\|M16, the Eagle Nebula]] in [[Serpens]] (RA 18h 19m)▼ [[Omega Nebula\|M17, the Omega Nebula]] in Sagittarius (RA 18h 20.4m)▼ [[Open Cluster M18]] in Sagittarius (RA 18h 19.9m)▼ [[Globular Cluster M55]] in Sagittarius (RA 19h 40m)▼ [[Small Sagittarius Star Cloud\|M24, the Small Sagittarius Star Cloud]] (RA 18h 17m)▼ [[Open Cluster M21]] in Sagittarius (RA 18h 5m)▼ [[Lagoon Nebula\|M8, the Lagoon Nebula]] in Sagittarius (RA 18h 4m)▼ [[Carina Nebula\|NGC 3372, the Carina Nebula]] in Carina (RA 10h 45m) ==~~Visible~~See ~~Objects~~also== [[Galactic disc]] ▲A number of [[Messier objects]], objects that are visible through an amateur's telescope or binoculars, are found in the Sagittarius Arm. ▲[[Lagoon Nebula\|M8, the Lagoon Nebula]] ▲[[Wild Duck Cluster\|M11, the Wild Duck Cluster]] ▲[[Eagle Nebula\|M16, the Eagle Nebula]] ▲[[Omega Nebula\|M17, the Omega Nebula]] ▲[[Open Cluster M18]] [[Trifid Nebula\|M20, the Trifid Nebula]] ▲[[Open Cluster M21]] ▲[[Sagittarius Star Cloud\|M24, the Sagittarius Star Cloud]] ▲[[Open Cluster M26]] ▲[[Globular Cluster M55]] ~~<div style="clear: both"></div>~~ ==~~Other resources~~References== {{Reflist}} ~~===See also===~~ [[List of Messier objects]] === External links= == * http://members.fcac.org/~sol/chview/chv5.htm [http://~~www~~messier.seds.org~~/messier~~/more/mw_m.html Messier Objects in the Milky Way (SEDS)]▼ http://skyandtelescope.com/mm_images/6829.jpg ▲*[http://www.seds.org/messier/more/mw_m.html Messier Objects in the Milky Way (SEDS)] ~~<br>~~ ~~{{Milky Way Footer}}~~ [[Category:Milky Way Galaxy]]▼ {{~~galaxy-stub~~Milky Way}} {{Portal bar\|Stars\|Spaceflight\|Outer space\|Solar System}} {{DEFAULTSORT:Carina-Sagittarius Arm}} [[Category:Carina–Sagittarius Arm\| ]] ▲[[Category:Milky Way ~~Galaxy~~arms]] [[Category:Galactic astronomy]] [[Category:Spiral galaxies]]