             APOD: 2018 February 18 - LL Ori and the Orion Nebula

                         Astronomy Picture of the Day

    Discover the cosmos! [1] Each day a different image or photograph of our
 fascinating universe is featured, along with a brief explanation written by a
                           professional astronomer.

                               2018 February 18
                                      [2]
                         LL Ori and the Orion Nebula
      Image Credit: NASA [3] , ESA [4] , and The Hubble Heritage Team [5]

Explanation: Stars can make waves in the Orion Nebula's sea of gas and dust.
This esthetic close-up [6] of cosmic clouds and stellar winds features LL
Orionis [7] , interacting with the Orion Nebula [8]  flow. Adrift in Orion's
stellar nursery [9] and still in its formative years, variable star LL Orionis
[10]  produces a wind more energetic than the wind [11]  from our own
middle-aged Sun. As the fast stellar wind runs into slow moving gas a shock
front is formed, analogous to the bow wave [12]  of a boat moving through
water or a plane traveling at supersonic [13]  speed. The small, arcing,
graceful structure just above and left of center is LL Ori's cosmic bow shock,
measuring about half a light-year across. The slower gas is flowing away from
the Orion Nebula [14] 's hot central star cluster, the Trapezium [15] ,
located off the upper left corner of the picture. In three dimensions [16] ,
LL Ori's wrap-around shock front is shaped like a bowl that appears brightest
when viewed along the "bottom" edge. This beautiful painting-like photograph
[17] is part of a large mosaic [18]  view of the complex [19] stellar nursery
in Orion, filled with a myriad of fluid [20] shapes [21]  associated with star
formation [22] .

                 Tomorrow's picture: Universe in B Sharp [23]

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Site notes:
  [1] archivepix.html
  [2] image/1802/LLOri_hubble_4806.jpg
  [3] http://www.nasa.gov/
  [4] http://www.spacetelescope.org/
  [5] http://heritage.stsci.edu/
  [6] http://hubblesite.org/newscenter/newsdesk/archive/releases/
2006/01/image/i
  [7] ap160522.html
  [8] ap060119.html
  [9] http://archive.ncsa.uiuc.edu/Cyberia/Bima/ StarForm.html
  [10] http://adsabs.harvard.edu/abs/2013MNRAS.428..691H
  [11] http://www-spof.gsfc.nasa.gov/Education/ wsolwind.html
  [12] http://www.ma.hw.ac.uk/solitons/LocalHeroes/sr.html
  [13] ap070819.html
  [14] https://www.youtube.com/watch?v=f32nnwgii4M
  [15] http://en.wikipedia.org/wiki/Trapezium_(astronomy)
  [16] http://mathforum.org/mathimages/index.php/Tesseract
  [17] http://hubblesite.org/image/1825/gallery
  [18] http://hubblesite.org/newscenter/newsdesk/archive/releases/ 2006/01/
  [19] http://cdsads.u-strasbg.fr/abs/2000AJ....119.2919B
  [20] ap990228.html
  [21] ap010504.html
  [22]
https://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve
  [23] ap180219.html
  [24] ap180217.html
  [25] archivepix.html
  [26] lib/apsubmit2015.html
  [27] lib/aptree.html
  [28] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [29] calendar/allyears.html
  [30] /apod.rss
  [31] lib/edlinks.html
  [32] lib/about_apod.html
  [33] http://asterisk.apod.com/discuss_apod.php?date=180218
  [34] ap180219.html
  [35] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [36] http://www.phy.mtu.edu/
  [37] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [38] http://www.astro.umd.edu/
  [39] lib/about_apod.html#srapply
  [40] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [41] https://astrophysics.gsfc.nasa.gov/
  [42] https://www.nasa.gov/
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