Your PDF has successfully downloaded.

You may be interested in finding more content on these topics:

Access

You are not currently logged in.

Access JSTOR through your library or other institution:

login

Log in through your institution.

Journal Article

Correcting Systematic Polarization Effects in Keck LRISp Spectropolarimetry to < 0.05%

David M. Harrington, Svetlana V. Berdyugina, Oleksii Kuzmychov and Jeffrey R. Kuhn
Publications of the Astronomical Society of the Pacific
Vol. 127, No. 954 (August 2015), pp. 757-775
DOI: 10.1086/682323
Stable URL: http://www.jstor.org/stable/10.1086/682323
Page Count: 19
Were these topics helpful?
See something inaccurate? Let us know!

Select the topics that are inaccurate.

Cancel
  • Download PDF
  • Add to My Lists
  • Cite this Item
We're having trouble loading this content. Download PDF instead.

Abstract

AbstractSpectropolarimetric measurements at moderate spectral resolutions are effective tracers of stellar magnetic fields and circumstellar environments when signal-to-noise ratios (S/Ns) above 2000 can be achieved. The LRISp spectropolarimeter is capable of achieving these S/Ns on faint targets with the 10 m aperture of the Keck telescope, provided several instrumental artifacts can be suppressed. We describe here several methods to overcome instrumental error sources that are required to achieve these high S/Ns on LRISp. We explore high S/N techniques such as defocusing and slit-stepping during integration with high spectral and spatial oversampling. We find that the instrument flexure and interference fringes introduced by the achromatic retarders create artificial signals at 0.5% levels in the red channel which mimic real stellar signals and limit the sensitivity and calibration stability of LRISp. Careful spectral extraction and data filtering algorithms can remove these error sources. For faint targets and long exposures, cosmic ray hits are frequent and present a major limitation to the upgraded deep depletion red-channel CCD. These must be corrected to the same high S/N levels, requiring careful spectral extraction using iterative filtering algorithms. We demonstrate here characterization of these sources of instrumental polarization artifacts and present several methods used to successfully overcome these limitations. We have measured the linear to circular cross-talk and find it to be roughly 5%, consistent with the known instrument limitations. We show spectropolarimetric signals on brown dwarfs are clearly detectable at 0.2% amplitudes with sensitivities better than 0.05% at full spectral sampling in atomic and molecular bands. Future LRISp users can perform high-sensitivity observations with high-quality calibration when following the described algorithms.

Notes and References

This item contains 74 references.

References
  • ['Adamson, A. J., & Whittet, D. C. B. 1995, ApJL, 448, L\xa049']
  • ['Afram, N., Berdyugina, S. V., Fluri, D. M., Solanki, S. K., & Lagg, A. 2008, A&A, 482, 387']
  • ['Afram, N., Berdyugina, S. V., Fluri, D. M., et al. 2007, A&A, 473, L\xa01']
  • ['Aitken, D. K., & Hough, J. H. 2001, PASP, 113, 1300']
  • ['Bagnulo, S., Fossati, L., Kochukhov, O., & Landstreet, J. D. 2013, A&A, 559, A\xa0103']
  • ['Bagnulo, S., Landolfi, M., Landstreet, J. D., et al. 2009, PASP, 121, 993']
  • ['Bailey, J., Kedziora-Chudczer, L., Cotton, D. V., et al. 2015, MNRAS, 449, 3064']
  • ['Bailey, J., Lucas, P. W., & Hough, J. H. 2010, MNRAS, 405, 2570']
  • ['Bailey, J., Ulanowski, Z., Lucas, P. W., et al. 2008, MNRAS, 386, 1016']
  • ['Berdyugin, A. V., Berdyugina, S. V., Piirola, V., & Butkevich, A. G. 2006, ApJ, 651, 475']
  • ['Berdyugina, S. V. 2011, Solar Polarization 6, Maui, 437, 219']
  • ['Berdyugina, S. V., Berdyugin, A. V., Fluri, D. M., & Piirola, V. 2008a, ApJ, 673, L\xa083']
  • ['Berdyugina, S. V., Berdyugin, A. V., Fluri, D. M., & Piirola, V. 2011, ApJL, 728, L\xa06']
  • ['Berdyugina, S. V., Fluri, D. M., Afram, N., et al. 2008b, 14th Cambridge Workshop on Cool Stars, 384, 175']
  • ['Clarke, D. 2005, A&A, 434, 377']
  • ['Cohen, J., & Shopbell, P. 1996, Keck LRIS Flexure at the Zenith, 1']
  • ['Cohen, M. H. 2005, The Keck LRIS Polarimeter Operators Manual, 1']
  • ['Dahlberg, A. R., Pust, N. J., & Shaw, J. A. 2009, Polarization Science and Remote Sensing IV, ed. Shaw, J. A., 7461, 6']
  • ['Dahlberg, A. R., Pust, N. J., & Shaw, J. A. 2011, Opt. Express, 19, 16008']
  • ['de Wijn, A. G., Tomczyk, S., Casini, R., & Nelson, P. G. 2010, Ground-Based and Airborne Instrumentation for Astronomy III, ed. McLean, I. S., 7735, 143']
  • ['del Toro Iniesta, J. C. 2003, Instituto de Astrofisica de Andalucia: Introduction to Spectropolarimetry']
  • ['del Toro Iniesta, J. C., & Collados, M. 2000, Appl. Opt., 39, 1637']
  • ['Donati, J.-F., Catala, C., Wade, G. A., et al. 1999, A&A, 134, 149']
  • ['Donati, J.-F., Semel, M., Carter, B. D., Rees, D. E., & Collier Cameron, A. 1997, MNRAS, 291, 658']
  • ['Elmore, D. F., Lin, H., Socas Navarro, H., & Jaeggli, S. A. 2010, Ground-Based and Airborne Instrumentation for Astronomy III, ed. McLean, I. S., 7735, 147']
  • ['Elmore, D. F., Lites, B. W., Tomczyk, S., et al. 1992, in Polarization Analysis and Measurement; Proceedings of the Meeting, Boulder, CO, 22–33']
  • ['Gehrels, T. 1974, in Planets, Stars and Nebulae Studied with Photopolarimetry (Tucson: University of Arizona Press)']
  • ['Goodrich, R. 2007, Keck Instrument Technical Note LRIS Polarimetry with the ADC, 1']
  • ['Goodrich, R., & Cohen, M. 2003, Proc. SPIE, 4843, 146']
  • ['Goodrich, R. W. 1991, PASP, 103, 1314']
  • ['Goodrich, R. W., Cohen, M. H., & Putney, A. 1995, PASP, 107, 179']
  • ['Harries, T. J., & Howarth, I. D. 1996, A&A, 310, 533']
  • ['Harrington, D. M., & Kuhn, J. R. 2008, PASP, 120, 89']
  • ['Harrington, D. M., Kuhn, J. R., & Hall, S. 2011, PASP, 123, 799']
  • ['Harrington, D. M., Kuhn, J. R., Sennhauser, C., Messersmith, E. J., & Thornton, R. J. 2010, PASP, 122, 420']
  • ['Horne, K. 1986, PASP, 98, 609']
  • ['Hough, J. H., Lucas, P. W., Bailey, J. A., et al. 2006, PASP, 118, 1302']
  • ['Johns-Krull, C. M., & Valenti, J. A. 1996, ApJL, 459, L\xa095']
  • ['Johns-Krull, C. M., & Valenti, J. A. 2000, Stellar Clusters and Associations: Convection, 198, 371']
  • ['Keck Telescope 2011, LRIS Flexure Report, September 19, 2011, Version 2.0, Tech. rep., Keck Telescope']
  • ['Keil, S. L., Rimmele, T. R., Wagner, J., & Elmore, D.Team, A. 2011, Solar Polarization 6, Maui, 437, 319']
  • ['Keller, C. U. 1996, Sol. Phys., 164, 243']
  • ['Kuzmychov, O., & Berdyugina, S. V. 2013, A&A, 558, A\xa0120']
  • ['Kuzmychov, O., Berdyugina, S. V., Harrington, D., & Kuhn, J. 2013, Mem. Soc. Astron. Italiana, 84, 1127']
  • ['Kuzmychov, O., Berdyugina, S. V., & Harrington, D. M. 2014, Cambridge Proceedings, 1, 441']
  • ['Marsh, T. R. 1989, PASP, 101, 1032']
  • ['McCarthy, J. K., Cohen, J. G., Butcher, B., et al. 1998, Proc. SPIE, 3355, 81']
  • ['Nagaraju, K., Ramesh, K. B., Sankarasubramanian, K., & Rangarajan, K. E. 2007, Bull. Astron. Soc. India, 35, 307']
  • ['Oke, J. B., Cohen, J. G., Carr, M., et al. 1995, PASP, 107, 375']
  • ['Pereyra, A., Rodrigues, C. V., & Martioli, E. 2015, A&A, 573, A\xa0133']
  • ['Pettersen, B. R., Coleman, L. A., & Evans, D. S. 1984, ApJ, 282, 214']
  • ['Phillips, A. C., Miller, J., Cowley, D., & Wallace, V. 2008, Ground-based and Airborne Instrumentation for Astronomy II, ed. McLean, I. S., 7014, 701453']
  • ['Pust, N. J., & Shaw, J. A. 2006, Appl. Opt., 45, 5470']
  • ['Pust, N. J., & Shaw, J. A. 2007, Polarization Science and Remote Sensing III, ed. Shaw, 6682, 3']
  • ['Pust, N. J., & Shaw, J. A. 2009, Polarization Science and Remote Sensing IV, ed. Shaw, 7461, 10']
  • ['Rockosi, C., Stover, R., Kibrick, R., et al. 2010, Proc. SPIE, 7735']
  • ['Saar, S. H. 1994, in IAU Symp. 154, Infrared Solar, ed. D. M. Rabin, 493']
  • ['Semel, M. 2003, A&A, 401, 1']
  • ['Semel, M., Donati, J.-F., & Rees, D. E. 1993, A&A, 278, 231']
  • ['Shaw, J. A., Pust, N. J., Staal, B., Johnson, J., & Dahlberg, A. R. 2010, Proc. SPIE, 7672']
  • ['Snik, F., Karalidi, T., & Keller, C. 2009, Appl. Opt., 48, 1337']
  • ['Snik, F., & Keller, C. U. 2013, in Planets, Stars and Stellar Systems (Dordrecht: Springer), 175–221']
  • ['Snik, F., van Harten, G., Navarro, R., et al. 2012, Proc. SPIE, 844625']
  • ['Swindle, R. 2014, PhD thesis, University of Hawai’i at Manoa']
  • ['Swindle, R., & Kuhn, J. R. 2014, PASJ, in press, 1']
  • ['Tinbergen, J. 2005, Astronomical Polarimetry (Cambridge: Cambridge University Press)']
  • ['Tinbergen, J. 2007, PASP, 119, 1371']
  • ['Tomczyk, S., Casini, R., de Wijn, A. G., & Nelson, P. G. 2010, Appl. Opt., 49, 3580']
  • ['Tran, H. D. 1995a, ApJ, 440, 565']
  • ['Tran, H. D. 1995b, ApJ, 440, 578']
  • ['Tran, H. D. 1995c, ApJ, 440, 597']
  • ['Tran, H. D., Cohen, M. H., & Goodrich, R. W. 1995, AJ, 110, 2597']
  • ['Tran, H. D., Lyke, J. E., & Mader, J. A. 2011, ApJL, 726, L\xa021']
  • ['Wiktorowicz, S. J., & Matthews, K. 2008, PASP, 120, 1282']