Astronomy Picture of the Day

Discover the cosmos! <https://apod.nasa.gov/apod/archivepix.html> Each
day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional
astronomer.

2018 August 5
See Explanation. Clicking on the picture will download the highest
resolution version available.
<https://apod.nasa.gov/apod/image/1808/OrionTrapezium_HubbleGendler_4000.jpg>


*Trapezium: At the Heart of Orion *
*Image Credit: * /Data: / Hubble Legacy Archive <http://hla.stsci.edu/>,
/Processing: / Robert Gendler <http://www.robgendlerastropics.com/>

*Explanation: * Near the center of this sharp cosmic portrait
<http://www.robgendlerastropics.com/TrapMosaic-HST-Gendler.html>, at the
heart of the Orion Nebula <https://apod.nasa.gov/apod/ap090222.html>,
are four hot, massive stars known as the Trapezium
<http://messier.seds.org/more/m042_trapezium.html>. Gathered within a
region about 1.5 light-years in radius, they dominate the core of the
dense Orion Nebula Star Cluster. Ultraviolet
<https://science.nasa.gov/ems/10_ultravioletwaves> ionizing radiation
from the Trapezium stars
<https://en.wikipedia.org/wiki/Trapezium_Cluster>, mostly from the
brightest star Theta-1 Orionis C
<http://stars.astro.illinois.edu/sow/theta1ori.html> powers the complex
star forming region's entire visible glow. About three million years
old, the Orion Nebula Cluster was even more compact in its younger years
and a recent dynamical study
<http://adsabs.harvard.edu/abs/2012ApJ...757...37S> indicates that
runaway stellar collisions
<http://www.skyandtelescope.com/community/skyblog/newsblog/A-Black-Hole-in-Orion-171183711.html>
at an earlier age may have formed a black hole with more than 100 times
the mass of the Sun
<https://solarsystem.nasa.gov/solar-system/sun/in-depth/>. The presence
of a black hole <https://apod.nasa.gov/apod/ap141026.html> within the
cluster could explain the observed high velocities of the Trapezium
stars <https://apod.nasa.gov/apod/ap170321.html>. The Orion Nebula's
distance of some 1,500 light-years
<https://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html>
would make it the closest known black hole
<https://en.wikipedia.org/wiki/List_of_nearest_black_holes> to planet
Earth.

*APOD Event: * APOD Editor to speak at Fermilab on August 8
<https://www.facebook.com/events/224564531505324/>
*Tomorrow's picture: *cosmic streaks

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*Authors & editors: * Robert Nemiroff
<http://www.phy.mtu.edu/faculty/Nemiroff.html> (MTU
<http://www.phy.mtu.edu/>) & Jerry Bonnell
<https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html> (UMCP
<http://www.astro.umd.edu/>)
*NASA Official: * Phillip Newman Specific rights apply
<https://apod.nasa.gov/apod/lib/about_apod.html#srapply>.
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<https://www.nasa.gov/> / GSFC <https://www.nasa.gov/centers/goddard/>
*&* Michigan Tech. U. <http://www.mtu.edu/>