NGC 2261

NGC 2261
Reflection nebula
An image of NGC 2261 by the Hubble space telescope.
Credit: HST/NASA/JPL/Judy Schmidt .
Observation data: J2000.0 epoch
Subtype variable nebula
Right ascension 6h 39m 10s[1]
Declination +8° 45′[1]
Distance 2,500 ly
Apparent magnitude (V) 9.0
Apparent dimensions (V) 2′
Constellation Monoceros
Designations Hubble's Variable Nebula,[1] Caldwell 46

NGC 2261 (also known as Hubble's Variable Nebula or Caldwell 46) is a variable nebula located in the constellation Monoceros. The nebula is illuminated by the star R Monocerotis (R Mon), which is not directly visible itself.

Observing history

NGC 2261 was discovered in 1783 by William Herschel.[2]

NGC 2261 was imaged as Palomar Observatory's Hale Telescope's first light by Edwin Hubble on January 26, 1949,[3] some 20 years after the Palomar Observatory project began in 1928. Hubble had studied the nebula previously at Yerkes and Mt. Wilson.[3] Hale had taken photographic plates with a 24 inch (60.96 cm) reflecting telescope in 1916.[4] Also, plates were taken using the same telescope in 1908 by FC Jordan, this allowed Hale to use of a blink comparator to study any changes in the nebula.[5]

NGC 2261 was imaged by the Hubble Space Telescope, and an image of the nebula was released in 1999.[6]

Descriptions

The star R Monocerotis has lit up a nearby cloud of gas and dust, but the shape and brightness slowly changes visible even in small telescopes over weeks and months, and the nebula looks like a small comet.[7]

One explanation proposed for the variability is that dense clouds of dust near R Mon periodically block the illumination from the star.[8] This casts a temporary shadow on the nearly clouds.[9]

See also

References

  1. 1 2 3 "NGC 2261". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2007-04-11.
  2. ↑ "Hubble's Variable Nebula". www.nightskyinfo.com. Retrieved 2018-07-25.
  3. 1 2 http://365daysofastronomy.org/2009/01/26/january-26-60th-anniversary-of-hale-telescope-first-light/
  4. ↑ "1916ApJ....44..190H Page 190". adsabs.harvard.edu. Retrieved 2018-07-25.
  5. ↑ "1916ApJ....44..190H Page 190". adsabs.harvard.edu. Retrieved 2018-07-25.
  6. ↑ information@eso.org. "Hubble's variable nebula (NGC 2261)". www.spacetelescope.org. Retrieved 2018-07-25.
  7. ↑ "Hubble's Variable Nebula, NGC 2261". Planetary Science Institute. 2010-10-15. Retrieved 2018-07-25.
  8. ↑ "A model for the cometary nebula NGC 2261". SAO/NASA ADS Astronomy Abstract Service. Retrieved 2010-11-28.
  9. ↑ "NGC 2261: Hubble's Variable Nebula | Science Mission Directorate". science.nasa.gov. Retrieved 2018-07-25.
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