University of Hertfordshire

Professor Sean Ryan

Professor

Sean Ryan

Professor Sean Ryan

Professor

Postal address:
University of Hertfordshire, Hatfield, Hertfordshire
United Kingdom

Publications

  1. 2019
  2. Imaging of X-Ray-Excited Emissions from Quantum Dots and Biological Tissue in Whole Mouse

    Ryan, S. G., Butler, M. N., Adeyemi, S., Kalber, T., Patrick, P. S., Thin, M. Z., Harrison, I. F., Stuckey, D. J., Pule, M. & Lythgoe, M., 29 Nov 2019, (Accepted/In press) In : Scientific Reports.

    Research output: Contribution to journalArticle

  3. 2016
  4. The Rotation of the halo of NGC 6822 from the radial velocities of carbon stars

    Thompson, G., Ryan, S. & Sibbons, L., 1 Nov 2016, In : Monthly Notices of the Royal Astronomical Society. 462, p. 3376-3385 20 p.

    Research output: Contribution to journalArticle

  5. 2015
  6. A three-dimensional hydrodynamical line profile analysis of iron lines and barium isotopes in HD140283

    Gallagher, A. J., Ludwig, H. G., Ryan, S. G. & Aoki, W., 31 Jul 2015, In : Astronomy & Astrophysics. 579, 16 p., A94.

    Research output: Contribution to journalArticle

  7. Spectral classification of photometrically selected AGB candidates in NGC 6822

    Sibbons, L. F., Ryan, S. G., Napiwotzki, R. & Thompson, G. P., 2 Feb 2015, In : Astronomy and Astrophysics. 574, 33 p., A102.

    Research output: Contribution to journalArticle

  8. The AGB population in IC 1613 using JHK photometry

    Sibbons, L. F., Ryan, S. G., Irwin, M. & Napiwotzki, R., 1 Jan 2015, In : Astronomy and Astrophysics. 573, 15 p., A84.

    Research output: Contribution to journalArticle

  9. 2013
  10. The Most Metal-Poor Stars. IV: The Two Populations with [Fe/H] <~ -3.0

    Norris, J., Yong, D., Bessell, M., Christlieb, N., Asplund, M., Gilmore, G. F., Wyse, R. F. G., Beers, T., Barklem, P., Frebel, A. & Ryan, S. G., 1 Jan 2013, In : The Astrophysical Journal. 762, 1, p. 28-46 19 p.

    Research output: Contribution to journalArticle

  11. The Most Metal-poor Stars. I: Discovery, Data and Atmospheric Parameters

    Norris, J., Bessell, M., Yong, D., Christlieb, N., Barklem, P., Asplund, M., Murphy, M., Beers, T., Frebel, A. & Ryan, S. G., Jan 2013, In : The Astrophysical Journal. 762, 25.

    Research output: Contribution to journalArticle

  12. The Most Metal-poor Stars. II: Chemical Abundances of 190 Metal-poor Stars Including 10 New Stars with [Fe/H] <= -3.5

    Yong, D., Norris, J., Bessell, M. S., Asplund, M., Beers, T. C., Barklem, P. S., Frebel, A. & Ryan, S. G., Jan 2013, In : The Astrophysical Journal. 762, 26.

    Research output: Contribution to journalArticle

  13. The Most Metal-poor Stars. III: The Metallicity Distribution Function and Carbon-enhanced Metal-poor Fraction

    Yong, D., Norris, J., Bessell, M., Christlieb, N., Asplund, M., Beers, T., Barklem, P., Frebel, A. & Ryan, S. G., 2013, In : The Astrophysical Journal. 762, 1, 27.

    Research output: Contribution to journalArticle

  14. 2012
  15. The AGB population of NGC 6822: Distribution and the C/M ratio from JHK photometry.

    Sibbons, L. F., Ryan, S. G., Cioni, M-RL., Irwin, M. & Napiwotzki, R., Apr 2012, In : Astronomy & Astrophysics. 540, 24 p., A135.

    Research output: Contribution to journalArticle

  16. The barium isotopic fractions in five metal-poor stars

    Gallagher, A., Ryan, S. G., Hosford, A., Garcia Perez, A. E., Aoki, W. & Honda, S., 2012, In : Astronomy and Astrophysics. 538, p. 118-128 11 p., A118.

    Research output: Contribution to journalArticle

  17. 2010
  18. Lithium abundances of halo dwarfs based on excitation temperatures. II: Non-local thermodynamic equilibrium

    Hosford, A., Perez, A. E. G., Collet, R., Ryan, S. G., Norris, J. E. & Olive, K. A., 2010, In : Astronomy and Astrophysics. 511, 12 p., 47.

    Research output: Contribution to journalArticle

  19. The SALT HRS spectrograph: final design, instrument capabilities, and operational modes

    Bramall, D. G., Sharples, R., Tyas, L., Schmoll, J., Clark, P., Luke, P., Looker, N., Dipper, N. A. & Ryan, S. G., 2010, In : Proceedings of the SPIE. 7735, 77354F.

    Research output: Contribution to journalArticle

  20. The barium isotopic mixture for the metal-poor subgiant star HD 140283

    Gallagher, A. J., Ryan, S. G., Garcia Perez, A. E. & Aoki, W., 2010, In : Astronomy and Astrophysics. 523, 15 p., 24.

    Research output: Contribution to journalArticle

  21. 2009
  22. 6Li/7Li estimates for metal-poor stars

    Garcia Perez, A. E., Aoki, W., Inoue, S., Ryan, S. G., Suzuki, T. K. & Chiba, M., Sep 2009, In : Astronomy and Astrophysics. 504, 1, p. 213-223

    Research output: Contribution to journalArticle

  23. Lithium abundances of halo dwarfs based on excitation temperature I: Local thermodynamic equilibrium

    Hosford, A., Ryan, S. G., Garcia Perez, A. E., Norris, J. E. & Olive, K. A., Jan 2009, In : Astronomy and Astrophysics. 493, 2, p. 601-612

    Research output: Contribution to journalArticle

  24. 2008
  25. A new sample of extremely/ultra metal-poor stars

    Perez, A. E. G., Christlieb, N., Ryan, S. G., Beers, T. C., Aoki, W., Asplund, M., Barklem, P. S., Bessell, M. S., Eriksson, K., Frebel, A., Gustafsson, B., Korn, A. J., Nordstrom, B. & Norris, J. E., Dec 2008, In : Physica Scripta. T133, 014036.

    Research output: Contribution to journalArticle

  26. Carbon-Enhanced Metal-Poor Stars. III: Main-Sequence Turn-Off Stars from the SDSS/SEGUE Sample

    Aoki, W., Beers, T. C., Sivarani, T., Marsteller, B., Lee, Y. S., Honda, S., Norris, J. E., Ryan, S. G. & Carollo, D., 10 May 2008, In : The Astrophysical Journal. 678, 2, p. 1351-1371

    Research output: Contribution to journalArticle

  27. Limits on Reddening and Gas-to-Dust Ratios for Seven Intermediate Redshift Damped Ly-alpha Absorbers from Diffuse Interstellar Bands

    Lawton, B., Churchill, C. W., York, B. A., Ellison, S. L., Snow, T. P., Johnson, R., Ryan, S. G. & Benn, C., 2008, In : The Astronomical Journal . 136, p. 994-1012

    Research output: Contribution to journalArticle

  28. Lithium isotopic abundances in old stars

    Perez, A. E. G., Inoue, S., Aoki, W. & Ryan, S. G., 2008, In : ESO Astrophysics Symposia. p. 9-13 5 p.

    Research output: Contribution to journalArticle

  29. 2007
  30. Carbon enhanced metal-poor stars I: Chemical compositions of 26 stars

    Aoki, W., Beers, T. C., Christlieb, N., Norris, J. E., Ryan, S. G. & Tsangarides, S., 2007, In : The Astrophysical Journal. 655, p. 492-521

    Research output: Contribution to journalArticle

  31. Experimental Mg I oscillator strengths and radiative lifetimes for astrophysical applications on metal-poor stars: New data for the Mg I b triplet

    Aldenius, M., Tanner, J. D., Johansson, S., Lundberg, H. & Ryan, S. G., 2007, In : Astronomy and Astrophysics. 461, 2, p. 767-773

    Research output: Contribution to journalArticle

  32. Spectroscopic studies of extremely metal-poor stars with the Subaru high dispersion spectrograph. IV: The alpha-element-enhanced metal-poor star BS16934-002

    Aoki, W., Honda, S., Beers, T. C., Takada-Hidai, M., Iwamoto, N., Tominaga, N., Umeda, H., Nomoto, K., Norris, J. E. & Ryan, S. G., 2007, In : The Astrophysical Journal. 660, p. 747-761

    Research output: Contribution to journalArticle

  33. 2006
  34. A high-resolution spectral analysis of three carbon-enhanced metal-poor stars

    Goswami, A., Aoki, W., Beers, T. C., Christlieb, N., Norris, J. E., Ryan, S. G. & Tsangarides, S., 2006, In : Monthly Notices of the Royal Astronomical Society. 372, p. 343-356

    Research output: Contribution to journalArticle

  35. Carbon-enhanced metal-poor stars. Osmium and iridium abundances in the neutron-capture-enhanced subgiants CS31062-050 and LP625-44

    Aoki, W., Bisterzo, S., Gallino, R., Beers, T. C., Norris, J. E., Ryan, S. G. & Tsangarides, S., 2006, In : The Astrophysical journal. 650, p. L127-L130

    Research output: Contribution to journalArticle

Previous 1 2 3 Next