Stellar Coronae

Stellar coronae are hot ionized plasmas in the outer atmospheres of most stars. X-ray spectra now being obtained for the first time by the Chandra and XMM-Newton observatories allow us to determine the thermal structure, densities, and dynamics of stellar coronae. We are now analyzing Chandra spectra of late-type stars (stars with convective zones like the Sun) to infer these properties and to determine the roles played by magnetic fields in stellar coronae. The figure above shows Chandra spectrum of the dM1e dwarf star AU Microscopii with the important emission lines marked. The top panel is from the Medium Energy Grating (MEG) and the bottom panel is from the High Energy Grating (HEG). Analysis of the line fluxes leads to the emission measure distribution, electron densities, and a model for the coronal plasma of the star.

Research Objectives:

• Analyze X-ray and EUV spectra of stars using the Chandra, XMM-Newton, and EUVE satellites.
• Determine the physical properties and structure of the coronae of active and quiescent late-type stars and binary systems.
• Search for X-ray emission from A and B-type stars.
• Study flare dynamics and energetics using high resolution X-ray and UV spectra of coronal emission lines.
• Analyze the nonthermal radio emission from late-type stars.

Recent Publications:

• Linsky, J.L., Gagne', M., Mytyk, A., McCaughren, M., and Andersen, M.: "The Eagle Nebula: Pillars of Creation, EGGs, and PMS Stars in NGC 6611", in Cool Stars 14, Astronomical Society of the Pacific Conference Series, to appear
• Linsky, J.L., Gagne', M., Mytyk, A., McCaughren, M., and Andersen, M.: "Chandra Observations of the Eagle Nebula. I., Embedded Young Stellar Objects near the Pillars of Creation", Astrophysical Journal, 654, 347
• Linsky, J.L.: 2006, "Stellar Magnetic Fields and Signatures of Heating", invited paper presented at session D2.2/E3.2 of the COSPAR meeting in Beijing, China, July 17, 2006, powerpoint presentation
• Wood, B.E. and Linsky, J.L.: 2006, "Coronal Emission Measures and Abundances for Moderately Active K Dwarfs Observed by Chandra", Astrophysical Journal, 643, 444
• Linsky, J.L.: 2004, "Summary of Cool Stars, Stellar Systems, and the Sun", powerpoint presentation
• Osten, R.A., Brown, A., Ayres, T.A., Drake, S.A., Franciosini, E., Pallavicini, R., Tagliaferri, G., Stewart, R.T., Skinner, S.L., and Linsky, J.L.: 2004, "A multi-wavelength perspective of flares on HR 1099: Four years of coordinated campaigns", Astrophysical Journal Supplements, 153, 317
• Guedel, M., Audard, M., Reale, F., Skinner, S.L., and Linsky, J.L.: 2004, "Flares from small to large: X-ray spectroscopy of Proxima Centauri with XMM-Newton", Astronomy and Astrophysics, 416, 713
• Linsky, J.L.: 2003, "Why high spectral resolution is needed for the Constellation-X mission", Presentation given at the Constellation-X Spectroscopy Workshop 2003, Columbia University
• Linsky, J.L.: 2003, "X-ray coronae of stars: Recent results from Chandra", Advances in Space Research, 32, No. 6, 917
• Redfield, S., Ayres, T.R., Linsky, J.L., Ake, T.B., Dupree, A.K., Robinson, R.D., and Young, P.R.: 2003, "A Far Ultraviolet Spectroscopic Explorer survey of coronal forbidden lines in late-type stars", Astrophysical Journal, 585, 993
• Ayres, T.R., Brown, A., Harper, G.M., Osten, R.A., Linsky, J.L., Wood, B.E., and Redfield, S.: 2003, "Space Telescope Imaging Spectrograph Survey of far-ultraviolet coronal forbidden lines in late-type stars", Astrophysical Journal, 583, 963
• Osten, R.A., Ayres, T.R., Brown, A., Linsky, J.L., and Krishnamurthi, A.: 2003, "Chandra, Extreme Ultraviolet Explorer, and Very Large Array observations of the active binary system Sigma2 Coronae Borealis", Astrophysical Journal, 582, 1073
• Linsky, J.L., Ayres, T.R., Brown, A., and Osten, R.A.: 2002, "Comparison of the spectrum of a sunspot-like star with a sunspot", Astronomische Nachrichten, 323, 321
• Linsky, J.L.: 2002, "Historical perspective -- Lessons learned and lessons to be learned", in Stellar Coronae in the Chandra and XMM Era, ed. F. Favata and J. Drake, ASP Conf. Series, 277, 3
• Linsky, J.L.: 2002, "Crazy coronal abundances", in X-rays at Sharp Focus, ASP Conf. Series, 262, 45
• Daniel, K., Linsky, J.L., and Gagne, M.: 2002, "Chandra observations of the Pleiades Open Cluster: X-ray emission from some late-B to early-A stars", Astrophysical Journal, 578, 486
• Robinson, R.D., Linsky, J.L., Woodgate, B.E., and Timothy, J.G.: 2001, "Far-ultraviolet observations of flares on the dM0e star AU Microscopii", Astrophysical Journal, 554, 368
• Linsky, J.L., Ayres, T.R., Brown, A., Osten, R., Skinner, S., and Gagne, M.: 2001, "Stellar coronae: new insights into fundamental questions", in New Century of X-ray Astronomy, ASP Conf. Series, 251, 22
• Linsky, J.L., Skinner, S., Osten, R., Gagne, M.: 2001, "Chandra spectra of three very active stars: AB Dor, 44i Boo, and Sigma2 CrB", in X-RAY Astronomy 2000, ed. R. Giaconni, L. Stella, and S. Serio, ASP Conf. Series, 234, 65
• Linsky, J.L., Skinner, S., Osten, R., Gagne, M.: 2001, "Chandra spectra of four very active stars: AB Dor, 44i Boo, and Sigma2 CrB and AU Mic", in Magnetic Fields Across the Hertzsprung-Russell Diagram, ed. G. Mathys, S.K. Solanki, and D.T. Wickramasinghe, ASP Conf. Series, 248, 255
• Ayres, T.R., Brown, A., Osten, R.A., Huenemoerder, D.P., Drake, J.J., Brickhouse, N.S., and Linsky, J.L.: 2001, "Chandra, EUVE, Hubble, and VLA multi-wavelength campaign on HR 1099: Instrumental capabilities, data reduction, and initial results", Astrophysical Journal, 549, 554
• Krishnamurthi, A., Reynolds, C.S., Linsky, J.L., Martin, E., and Gagne: 2001, "Observations of the core of the Pleiades with the Chandra X-ray Observatory", Astronomical Journal, 121, 337
• Leto, G., Pagano, I., Linsky, J.L., Rodono, M., and Umana, G.: 2000, "VLA observation of dMe stars", Astronomy and Astrophysics, 359, 1035
• Osten, R.A., Brown, A., Ayres, T.R., Linsky, J.L., Drake, S.A., Gagne, M., and Stern, R.A.: 2000, "Radio, X-ray, and Extreme-Ultraviolet coronal variability of the short-period RS Canum Venaticorum binary Sigma2 Coronae Borealis", Astrophysical Journal, 544, 953
• Linsky, J.L.: 2000, "Stellar flares: How common? How important?", in Cosmic Explosions, ed. S.S. Holt and W.W. Zhang (Melville NY: Am. Institute of Physics), p. 389
• Linsky, J.L., Krishnamurthi, A., Gagne, M., and Guedel, M.: 2000, "Are the shapes of coronal emission measure distributions controlled by rotation and convection zone parameters?", in Stellar Clusters and Associations, ed. R. Pallavicini, G. Micela, and S. Sciortino (San Francisco: Astron. Soc. Pacific), p. 467
• Linsky, J.L.: "Comparing solar and stellar activity: new results from HST, Chandra, and XMM", invited talk at the American Astronomical Society Solar Physics Division meeting, State Line, NV, June 20, 2000
• Linsky, J.L.: 2000, "Microarcsecond X-ray imaging of stars", invited talk at the MAXIM Pathfinder Mission Definition Team meeting, Goddard Space Flight Center, Greenbelt MD, Sept 18, 2000
• Linsky, J.L.: 2000, "What have we learned? Where are we going? And some lessons from the past", in Stellar Clusters and Associations, ed. R. Pallavicini, G. Micela, and S. Sciortino (San Francisco: Astron. Soc. Pacific), p. 563