A Study of the Extragalactic UV Radiation in Helix Nebula using GALEX


  • Lakshmi S BOSE Department of Physics, Faculty of Sree Narayana Mangalam College, Maliankara, Ernakulam, Kerala 693516, India




Diffuse UV, Extragalactic UV radiation, FUV-NUV fluxes, GALEX observations


We have studied the ultraviolet sources using Galaxy Evolution Explorer medium imaging surveys in Helix Nebula and estimated UV fluxes by using aperture photometry in distant and near ultraviolet bands. The aperture photometric method produces reliable, accurate flux measurements and found inconsistent with the merged catalog of Galaxy Evolution Explorer. From the current results, the fluxes are consistent with brighter absolute magnitude up to 24.5 and the measurement error increases gradually to more than 50 % at the fainter magnitude side. Percentage of error in far UV is greater than near UV, due to the fact that brighter galaxies are more visible than the near UV sources. The diffuse UV contributors of zodiacal light, airglow contribution in the nebula were estimated. The total extragalactic UV radiation from the detected sources to the diffuse background in the nebula is of the order of 50 ± 14 photons cm-2sr-1s-1Å-1 in NUV band and 28 ±10 photons cm-2sr-1s-1Å-1 in FUV band.


  • GALEX observations have the potential to find extragalactic UV sources
  • Helix Nebula is first identified for distinct source detection
  • Aperture photometric method can detect fainter sources up to the magnitude of 27
  • Extragalactic sources in the Helix nebula contribute to diffuse UV emission in the nebula



Download data is not yet available.


Metrics Loading ...


L Bianchi. GALEX and star formation. Astrophys. Space Sci. 2011; 335, 51-60.

R Cowen. On the trail of dead planets: Dust ring around a white dwarf. Sci. News 2007; 100, 171.

CR O’Dell and WJ Henney. A multi-instrument study of the Helix Nebula knots with the Hubble Space Telescope. Astrophys. J. 2005; 130, 172-87.

PAMV Hoof, GCVD Steene, KM Exter, MJ Barlow, T Ueta, MAT Groenewegen, WK Gear, HL Gomez, PC Hargrave, RJ Ivison, SJ Leeks, TL Lim, G Olofsson, ET Polehampton, BM Swinyard, HV Winckel, C Waelkens and R Wesson. A Herschel study of NGC 650. Astron. Astrophys. 2013; 560, A7.

GF Benedict, BE McArthur, R Napiwotzki, TE Harrison, HC Harris, ENelan, HE Bond, RJ Patterson and R Ciardullo. Astrometry with the Hubble Space Telescope: Trigonometric parallaxes of planetary Nebula nuclei NGC 6853, NGC 7293, ABELL 31, and DeHt5. Astron. J. 2009; 138, 1969-84

M Meixner, P McCullough, J Hartman, M Son and AK Speck. Molecular hydrogen knots in the Helix Nebula. Astron. J. 2005; 130, 1784-94.

PAMV Hoof, GCVD Steene, MJ Barlow, KM Exter, B Sibthorpe, T Ueta, V Peris, MAT Groenewegen, JADL Blommaert, M Cohen, WD Meester, GJ Ferland, WK Gear, HL Gomez, PC Hargrave, E Huygen, RJ Ivison, C Jean, SJ Leeks, TL Lim, G Olofsson, ET Polehampton, S Regibo, P Royer, BM Swinyard, B Vandenbussche, HV Winckel, C Waelkens, HJ Walker and R Wesson. Herschel images of NGC 6720: H2 formation of dust grains. Astron. Astrophys. 2010; 518, L137.

K Young, P Cox, PJ Huggins, T Forveille and R Bachiller. The molecular envelope of the Helix Nebula. Astrophys. J. 1999; 522, 387.

GCVD Steene, PAMV Hoof, KM Exter, MJ Barlow, J Cernicharo, M Etxaluze, WK Gear, JR Goicoechea, HL Gomez, MAT Groenewegen, PC Hargrave, RJ Ivison, SJ Leeks, TL Lim, M Matsuura, G Olofsson, ET Polehampton, BM Swinyard, T Ueta, HV Winckel, C Waelkens and R Wesson. Herschel imaging of the dust in the Helix Nebula (NGC 7293). Astron. Astrophys. 2015; 574, A134.

AK Speck, M Meixner, D Fong, PR McCullough, DE Moser and T Ueta. Large scale extended emission around the Helix Nebula: Dust, molecules, atoms and ions. Astron. J. 2002; 123, 346.

JL Hora, WB Latter, HA Smith and M Marengo. Infrared observations of the Helix planetary nebula. Astrophys. J. 2006; 652, 426-41.

R Bachiller, T Forveille, PJ Huggins and P Cox. The chemical evolution of planetary nebulae. Astron. Astrophys. 1997; 324, 1123-34.

ED Tenenbaum, SN Milam, NJ Woolf and LM Ziurys. Molecular survival in evolved planetary nebulae: Detection of H2CO, c-C3H2, and C2H in the Helix. Astrophys. J. 2009; 704, L108-L112.

LN Zack and LM Ziurys. Chemical complexity in the Helix Nebula: Multi-line observations of H2CO HCO+ and CO. Astrophys. J. 2013; 765, 112.

M Etxaluze, J Cernicharo, JR Goicoechea, PAMV Hoof, BM Swinyard, MJ Barlow, GCVD Steene, MAT Groenewegen, F Kerschbaum, TL Lim, F Lique, M Matsuura, C Pearson, ET Polehampton, P Royer and T Ueta. Herschel spectral mapping of the Helix Nebula (NGC 7293). Astron. Astrophys. 2014; 566, A78.

DC Martin, J Fanson, D Schiminovich, P Morrissey, PG Friedman, TA Barlow, T Conrow, R Grange, PN Jelinsky, B Milliard, OHW Siegmund, L Bianchi, YI Byun, J Donas, K Forster, TM Heckman, YW Lee, BF Madore, RF Malina, SG Neff, RM Rich, T Small, AS Szalay, TK Wyder. The galaxy evolution explorer: A space ultraviolet survey mission. Astrophys. J. 2005; 619, L1-L6.

L Bianchi, ADL Vega, B Shiao and R Bohlin. New UV-source catalogs, UV spectral database, UV variables and science tools from the GALEX surveys. Astrophys. Space Sci. 2018; 363, 56.

P Morrissey, T Conrow, TA Barlow, T Small, M Seibert, TK Wyder, T Budavári, S Arnouts, PG Friedman and K Forster. The calibration and data products of GALEX. Astrophys. J. Suppl. Ser. 2007; 173, 682.

L Bianchi. The ultraviolet sky surveys: Filling the gap in our view of the universe. Astrophys. Space Sci. 2009; 320, 11-9.

L Bianchi, B Shiao and D Thilker. Revised catalog of GALEX Ultraviolet Sources. I. The all-sky survey: GUVcat_AIS. Astrophys. J. Suppl. 2017; 230, 24.

DT Frayer, D Fadda, L Yan, FR Marleau, PI Choi, G Helou, BT Soifer, PN Appleton, L Armus and R Beck. Spitzer 70 and 160 μm observations of the extragalactic first look survey. Astron. J. 2006; 131, 250.

MAT Groenewegen, L Girardi, E Hatziminaoglou, C Benoist, LF Olsen, LD Costa, S Arnouts, R Madejsky, RP Mignani, C Rité, G Sikkema, R Slijkhuis and B Vandame. ESO imaging survey: the stellar catalogue in the Chandra deep field south. Astron. Astrophys. 2002; 392, 741-55.

LS Bose, NV Sujatha, K Narayanankutty and J Murthy. Extragalactic survey using GALEX-Spitzer matching fields. Astron. Lett. 2015; 41, 704-11.

S Bowyer. The cosmic far ultraviolet background. Ann. Rev. Astron. Astrophys. 1991; 29, 59-88.

RC Henry. Ultraviolet background radiation. Ann. Rev. Astron. Astrophys. 1991; 29, 89-127.

NV Sujatha, J Murthy, A Karnataki, RC Henry and L Bianchi. GALEX observation of diffuse UV radiation at high spaitial resolution from the Sandage Nebulosity. Astrophys. J. 2009; 692, 1333.

NV Sujatha, J Murthy, R Suresh, RC Henry and L Bianchi. GALEX observations of diffuse ultraviolet emission from Draco. Astrophys. J. 2010; 723, 1549-57.

C Leinert, S Bowyer, LK Haikala, MS Hanner, MG Hauser, AC Levasseur-Regourd, I Mann, K Mattila, WT Reach, W Schlosser, HJ Staude, GN Toller, JL Weiland, JL Weinberg and AN Witt. The 1997 reference of diffuse night sky brightness. Astron. Astrophys. Suppl. Ser. 1998; 127, 1-99.

DJ Schlegel, DP Finkbeiner and M Davis. Maps of dust infrared emission for use in estimation of reddening and cosmic microwave background radiation foregrounds. Astrophys. J. 1998; 500, 525.

LS Bose, NV Sujatha and K Narayanankutty. Ultraviolet and infrared correlation studies in Orion. Open Astron. 2015; 24, 319-26.




How to Cite

BOSE, L. S. . (2021). A Study of the Extragalactic UV Radiation in Helix Nebula using GALEX. Walailak Journal of Science and Technology (WJST), 18(18), Article 23982 (9 pages). https://doi.org/10.48048/wjst.2021.23982