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IC 4603: Reflection Nebula i
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| Title |
IC 4603: Reflection Nebula in Ophiuchius |
| Explanation |
Why does this starfield photograph resemble an impressionistic painting [ http://www.ibiblio.org/wm/paint/glo/impressionism/ ]? The effect is created not by digital trickery [ http://antwrp.gsfc.nasa.gov/apod/ap030324.html ] but by large amounts of interstellar dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ]. Dust, minute globs rich in carbon [ http://www.nyu.edu/pages/mathmol/modules/carbon/carbon1.html ] and similar in size [ http://www.lakeair.com/particle.html ] to cigarette smoke [ http://amos.indiana.edu/library/scripts/smoke.html ], frequently starts in the outer atmospheres of large, cool, young stars. The dust [ http://nedwww.ipac.caltech.edu/level5/March02/Li/Li_contents.html ] is dispersed as the star dies and grows as things stick to it in the interstellar medium [ http://www-ssg.sr.unh.edu/ism/intro.html ]. Dense dust clouds are opaque [ http://antwrp.gsfc.nasa.gov/apod/ap030202.html ] to visible light [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ] and can completely hide background stars. For less dense clouds, the capacity of dust to preferentially reflect blue [ http://www.why-is-the-sky-blue.org/why-is-the-sky-blue.html ] starlight becomes important, effectively blooming the stars blue light out and marking the surrounding dust. Nebular gas emissions, typically brightest in red light [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ], can combine to form areas seemingly created on an artist's canvas. Photographed above [ http://ryutao.main.jp/english/stl_ant.html ] is roughly four square degrees of the nebula IC 4603 [ http://antwrp.gsfc.nasa.gov/apod/ap060714.html ] near the bright star Antares [ http://en.wikipedia.org/wiki/Antares ] toward the constellation [ http://en.wikipedia.org/wiki/Constellation ] of Ophiuchus [ http://www.seds.org/Maps/Stars_en/Fig/ophiuchus.html ]. |
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A Close Encounter Of The Ste
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| Title |
A Close Encounter Of The Stellar Kind |
| Explanation |
The unassuming star centered in this sky view [ http://skyview.gsfc.nasa.gov ] will one day be our next door [ http://antwrp.gsfc.nasa.gov/apod/ap010318.html ] stellar neighbor. The faint 9th magnitude red dwarf [ http://antwrp.gsfc.nasa.gov/apod/ap991120.html ], currently 63 light-years away in the constellation Ophiucus [ http://www.seds.org/Maps/Stars_en/Fig/ophiuchus.html ], was recently discovered to be approaching our Solar System. Known in catalogs of nearby stars [ http://cdsweb.u-strasbg.fr/htbin/myqcat3?V/70A/ ] as Gliese (Gl) 710 it is predicted to come within nearly 1 light-year of the Sun ... about 1.5 million years from now. At that distance this star, presently much too faint to be seen [ http://liftoff.msfc.nasa.gov/academy/universe/MAG.HTML ] by the naked eye, will blaze at 0.6 magnitude - rivaling the apparent brightness of the mighty red giant Antares [ http://antwrp.gsfc.nasa.gov/apod/ap970624.html ]. Ultimately Gliese 710 poses no direct collision danger itself although its gravitational influence will likely scatter comets out of the Solar System's reservoir, the Oort cloud [ http://www.windows.umich.edu/cgi-bin/tour_def/comets/ Oort_cloud.html ], sending some inbound. This future stellar encounter [ http://adsabs.harvard.edu/cgi-bin/ nph-bib_query?bibcode=1999AJ....117.1042G&db_key=AST&high=3af6c03e8102908 ] was discovered by researchers Joan Garcia-Sanchez and Robert Preston (JPL [ http://www.jpl.nasa.gov ]), and collaborators while studying stars in the solar neighborhood [ http://www.clockwk.com/stars/ ] using data from the Hipparcos Astrometry Satellite [ http://astro.estec.esa.nl/SA-general/Projects/Hipparcos/ hipparcos.html ]. The star field shown is based on the Palomar Digitized Sky Survey [ http://www-gsss.stsci.edu/Dss/dss_home.HTM ] and is 1/4 degree wide (about half the diameter of the full moon). |
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IC 4603: Reflection Nebula i
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| Title |
IC 4603: Reflection Nebula in Ophiuchius |
| Explanation |
Why does this starfield photograph resemble an impressionistic painting [ http://www.ibiblio.org/wm/paint/glo/impressionism/ ]? The effect is created not by digital trickery [ http://antwrp.gsfc.nasa.gov/apod/ap030324.html ] but by large amounts of interstellar dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ]. Dust, minute globs rich in carbon [ http://www.nyu.edu/pages/mathmol/modules/carbon/carbon1.html ] and similar in size [ http://www.lakeair.com/particle.html ] to cigarette smoke [ http://amos.indiana.edu/library/scripts/smoke.html ], frequently starts in the outer atmospheres of large, cool, young stars. The dust [ http://nedwww.ipac.caltech.edu/level5/March02/Li/Li_contents.html ] is dispersed as the star dies and grows as things stick to it in the interstellar medium [ http://www-ssg.sr.unh.edu/tof/Outreach/Interstellar/index.html?what1.html ]. Dense dust clouds are opaque [ http://antwrp.gsfc.nasa.gov/apod/ap030202.html ] to visible light [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ] and can completely hide background stars. For less dense clouds, the capacity of dust to preferentially reflect blue [ http://www.why-is-the-sky-blue.org/why-is-the-sky-blue.html ] starlight becomes important, effectively blooming the stars blue light out and marking the surrounding dust. Nebular gas emissions, typically brightest in red light [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ], can combine to form areas seemingly created on an artist's canvas. Photographed above [ http://home.earthlink.net/~gstevens916/pic4603.htm ] is roughly one square degree of the nebula IC 4603 [ http://www.psiaz.com/Schur/astro/filmimagepages/rho.html ] near the bright star Antares [ http://antwrp.gsfc.nasa.gov/apod/ap980726.html ] toward the constellation [ http://www.adlerplanetarium.org/history/exhibits/constellations/timeline.html ] of Ophiuchus [ http://www.seds.org/Maps/Stars_en/Fig/ophiuchus.html ]. |
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The Dark River to Antares
| Title |
The Dark River to Antares |
| Explanation |
Connecting the Pipe Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap020526.html ] to the bright star Antares is a flowing dark cloud nicknamed the Dark River [ http://www.astropix.com/HTML/D_SUM_S/PIPE.HTM ]. The murkiness of the Dark River [ http://antwrp.gsfc.nasa.gov/apod/ap030928.html ] is caused by absorption of background starlight by dust [ http://antwrp.gsfc.nasa.gov/apod/ap030706.html ], although the nebula contains mostly hydrogen [ http://pearl1.lanl.gov/periodic/elements/1.html ] and molecular gas. Antares [ http://www.astro.uiuc.edu/~kaler/sow/antares.html ], the brightest star in the frame, is embedded in the colorful Rho Ophiuchi [ http://antwrp.gsfc.nasa.gov/apod/ap040602.html ] nebula clouds. The Dark River, pictured above [ http://www.starryscapes.com/nebula/rho_ophiuchus.html ] across the upper left, spans over 20 times the angular diameter of the Moon [ http://antwrp.gsfc.nasa.gov/apod/ap030810.html ] and lies about 500 light years [ http://chandra.harvard.edu/photo/cosmic_distance.html ] distant. Other types of nebula [ http://www.seds.org/billa/twn/antx.html ] visible here include red emission nebula [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ] and the blue reflection [ http://antwrp.gsfc.nasa.gov/apod/reflection_nebulae.html ] nebula. |
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A Close Encounter Of The Ste
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| Title |
A Close Encounter Of The Stellar Kind |
| Explanation |
The unassuming star centered in this sky view [ http://skyview.gsfc.nasa.gov ] will one day be our next door [ http://www.bigear.org/vol1no2/kraus.htm ] stellar neighbor [ http://www.astro.wisc.edu/~dolan/constellations/extra/nearest.html ]. The faint 9th magnitude red dwarf [ http://antwrp.gsfc.nasa.gov/apod/ap991120.html ], currently 63 light-years away [ http://zebu.uoregon.edu/~soper/Stars/parallax_ly.html ] in the constellation Ophiucus [ http://www.astro.wisc.edu/~dolan/constellations/constellations/ Ophiuchus.html ], was recently discovered to be approaching our Solar System. Known in catalogs of nearby stars [ http://tarkus.pha.jhu.edu/~thenry/RECONS.html ] as Gliese 710 it is predicted to come within 1 light-year of the Sun ... a million years from now. At that distance this star, presently much too faint to be seen [ http://liftoff.msfc.nasa.gov/academy/universe/MAG.HTML ] by the naked eye, will blaze at 0.6 magnitude - rivaling the apparent brightness of the mighty red giant Antares [ http://antwrp.gsfc.nasa.gov/apod/ap970624.html ]. Ultimately Gliese 710 poses no direct collision danger itself although its gravitational influence will likely scatter comets out of the Solar System's reservoir, the Oort cloud [ http://www.windows.umich.edu/cgi-bin/tour_def/comets/ Oort_cloud.html ], sending some inbound. This future stellar encounter [ http://cass.jsc.nasa.gov/meetings/dps97/html/H2501/H2501.html ] was discovered by researchers [ http://www.newscientist.com/ns/970524/doomstar.html ] Joan Garcia-Sanchez and Robert Preston (JPL [ http://www.jpl.nasa.gov ]), and collaborators while studying stars in the solar neighborhood [ http://www.clockwk.com/stars/ ] using data from the Hipparcos Astrometry Satellite [ http://astro.estec.esa.nl/SA-general/Projects/Hipparcos/ hipparcos.html ]. The star field shown is based on the Palomar Digitized Sky Survey [ http://www-gsss.stsci.edu/dss/dss.html ] and is 1/4 degree wide (about half the diameter of the full moon). |
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East of Antares
| Title |
East of Antares |
| Explanation |
East of Antares [ http://antwrp.gsfc.nasa.gov/apod/ap020526.html ], dark markings seem to sprawl through the crowded star fields toward the center of our Milky Way Galaxy. Cataloged in [ http://adsabs.harvard.edu/cgi-bin/ bib_query?1919ApJ....49....1B ] the early 20th century by astronomer E. E. Barnard [ http://astro.uchicago.edu/yerkes/virtualmuseum/ Barnardfull.html ], the obscuring interstellar dust clouds include [ http://www.saguaroastro.org/content/ Best-of-Barnards-Dark-Nebulae.htm ] B72 [ http://antwrp.gsfc.nasa.gov/apod/ap050521.html ], B77, B78, and B59, seen in silhouette [ http://antwrp.gsfc.nasa.gov/apod/ap001229.html ] against the starry background. Here, their combined shape suggests smoke rising from a pipe, and so the dark nebula's popular name is the Pipe Nebula. This gorgeous and expansive view [ http://panther-observatory.com/gallery/deepsky/doc/ Pipe_200mm.htm ] was recorded in very dark skies over Hakos, Namibia [ http://www.fallingrain.com/world/WA/40/Hakos.html ]. It covers a full 10 by 7 degree field in the pronounceable [ http://www.astronomyclub.org/learn/Say_What.htm ] constellation Ophiuchus. |
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