NGC 404

NGC 404

NGC 404 by Hubble Space Telescope; 1.68′ view
Observation data (J2000 epoch)
Constellation Andromeda
Right ascension 01h 09m 27.0s[1]
Declination +35° 43′ 04″[1]
Redshift -48 ± 9 km/s[1]
Distance 10.0 ± 0.7 Mly (3.07 ± 0.21 Mpc)[2][3][4][a]
Type SA(s)0-[1]
Apparent dimensions (V) 3′.5 × 3′.5[1]
Apparent magnitude (V) 11.2[1]
Other designations
UGC 718, PGC 4126[1]
See also: Galaxy, List of galaxies

NGC 404 is a small lenticular galaxy located about 10 million light years away in the constellation Andromeda. It was discovered by William Herschel in 1784, and is visible through small telescopes.[5] NGC 404 lies just beyond the Local Group but does not appear gravitationally bound to it. It is notable for being within 7 arc-minutes of second magnitude star Mirach, making it a difficult target to observe or photograph and granting it the nickname "Mirach's Ghost".

Contents

LINER emission

NGC 404 contains a low-ionization nuclear emission-line region (LINER), a type of region that is characterized by spectral line emission from weakly ionized atoms.[6]

Distance measurements

At least two techniques have been used to measure distances to NGC 404. The infrared surface brightness fluctuations distance measurement technique estimates distances to spiral galaxies based on the graininess of the appearance of their bulges. The distance measured to NGC 404 using this technique in 2003 is 9.9 ± 0.5 Mly (3.03 ± 0.15 Mpc).[2]

However, NGC 404 is close enough that red supergiants can be imaged as individual stars. The light from these stars and knowledge of how they should compare to nearby stars within the Milky Way galaxy allows for direct measurement of the distance to the galaxy. This method is referred to as the tip of the red giant branch (TRGB) method. The estimated distance to NGC 404 using this technique is 10.0 ± 1.2 Mly (3.1 ± 0.4 Mpc).[3] Averaged together, these distance measurements give a distance estimate of 10.0 ± 0.7 Mly (3.07 ± 0.21 Mpc).[a]

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External links

Notes

  1. ^ average(3.03 ± 0.15, 3.1 ± 0.4) = ((3.03 + 3.1) / 2) ± ((0.152 + 0.42)0.5 / 2) = 3.07 ± 0.21

References

  1. ^ a b c d e f g "NASA/IPAC Extragalactic Database". Results for NGC 404. http://nedwww.ipac.caltech.edu/. Retrieved 2006-11-18. 
  2. ^ a b Jensen, Joseph B.; Tonry, John L.; Barris, Brian J.; Thompson, Rodger I.; Liu, Michael C.; Rieke, Marcia J.; Ajhar, Edward A.; Blakeslee, John P. (February 2003). "Measuring Distances and Probing the Unresolved Stellar Populations of Galaxies Using Infrared Surface Brightness Fluctuations". Astrophysical Journal 583 (2): 712–726. arXiv:astro-ph/0210129. Bibcode 2003ApJ...583..712J. doi:10.1086/345430. 
  3. ^ a b I. D. Karachentsev, V. E. Karachentseva, W. K. Hutchmeier, D. I. Makarov (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal 127 (4): 2031–2068. Bibcode 2004AJ....127.2031K. doi:10.1086/382905. 
  4. ^ Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics 49 (1): 3–18. Bibcode 2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6. 
  5. ^ Mirach's Ghost (NGC 404), The Internet Encyclopedia of Science, David Darling. Accessed on line August 15, 2008.
  6. ^ Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W. (October 1997). "A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies". The Astrophysical Journal Supplement Series 112: pp. 315–390. doi:10.1086/313041. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1997ApJS..112..315H 

Coordinates: 01h 09m 27.0s, +35° 43′ 04″