by Ann » Sun Nov 01, 2020 10:36 am
Two parts of the Trifid Nebula are particularly interesting:
The Trifid Nebula is ionized by a small group of hot stars near its very center.
Wikipedia wrote:
The Trifid Nebula (catalogued as Messier 20 or M20 and as NGC 6514) is an H II region located in Sagittarius. (...) The object is an unusual combination of an open cluster of stars; an emission nebula (the lower, red portion), a reflection nebula (the upper, blue portion) and a dark nebula (the apparent 'gaps' within the emission nebula that cause the trifurcated appearance; these are also designated Barnard 85).
...
The Trifid Nebula is a star-forming region in the Scutum spiral arm of the Milky Way. The most massive star that has formed in this region is
HD 164492A, an O7.5III star with a mass more than 20 times the mass of the Sun. This star is surrounded by a cluster of approximately 3100 young stars.
According to Simbad, HD 164492 is a pre-main sequence star of spectral class O7.5Vz. Don't ask me what the "z" means. Anyway, Simbad suggests that HD 164492 is so young that it may not yet have initiated hydrogen fusion in its core. (I find that last claim just a little bit hard to believe.)
The picture at right does a better job than the APOD at showing which of the bright star at the center of the Trifid Nebula is HD 164492A. Please note the bright rim of the stubby dust pillar close to the small group of stars. Its bright rim means that it is being directly illuminated by the hot stars. Also note the bright outflow from the top of this stubby pillar. A new star is almost certainly being born here, but it is hidden by the dust pillar from our point of view.
Another dust pillar in the Trifid Nebula features two jets. Clearly two young stars are being born here, and during their birth pangs they emit long narrow jets.
Ann
Two parts of the Trifid Nebula are particularly interesting:
[float=left][img3="In the Center of the Trifid Nebula. Image Credit: Subaru Telescope (NAOJ), Hubble Space Telescope, Martin Pugh; Processing: Robert Gendler.
"]https://apod.nasa.gov/apod/image/2011/Trifid_HubbleGendler_960.jpg[/img3][/float][float=right][img3="The innermost part of the Trifid Nebula. NASA, ESA, and The Hubble Heritage Team (AURA/STScI)."]https://cdn.spacetelescope.org/archives/images/screen/opo0417b.jpg[/img3][/float]
The Trifid Nebula is ionized by a small group of hot stars near its very center.
[quote][url=https://en.wikipedia.org/wiki/Trifid_Nebula]Wikipedia[/url] wrote:
The Trifid Nebula (catalogued as Messier 20 or M20 and as NGC 6514) is an H II region located in Sagittarius. (...) The object is an unusual combination of an open cluster of stars; an emission nebula (the lower, red portion), a reflection nebula (the upper, blue portion) and a dark nebula (the apparent 'gaps' within the emission nebula that cause the trifurcated appearance; these are also designated Barnard 85).
...
The Trifid Nebula is a star-forming region in the Scutum spiral arm of the Milky Way. The most massive star that has formed in this region is [b][color=#0040FF]HD 164492A, an O7.5III star with a mass more than 20 times the mass of the Sun[/color][/b]. This star is surrounded by a cluster of approximately 3100 young stars.[/quote]
According to Simbad, HD 164492 is a pre-main sequence star of spectral class O7.5Vz. Don't ask me what the "z" means. Anyway, Simbad suggests that HD 164492 is so young that it may not yet have initiated hydrogen fusion in its core. (I find that last claim just a little bit hard to believe.)
The picture at right does a better job than the APOD at showing which of the bright star at the center of the Trifid Nebula is HD 164492A. Please note the bright rim of the stubby dust pillar close to the small group of stars. Its bright rim means that it is being directly illuminated by the hot stars. Also note the bright outflow from the top of this stubby pillar. A new star is almost certainly being born here, but it is hidden by the dust pillar from our point of view.
[float=right][img3="Trifid Pillars and Jets. Credit: J. Hester (Arizona St. U) et al., WFPC2, HST, NASA."]https://apod.nasa.gov/apod/image/0712/trifidpillars_hst.jpg[/img3][/float]
Another dust pillar in the Trifid Nebula features two jets. Clearly two young stars are being born here, and during their birth pangs they emit long narrow jets.
Ann