Stellar Coronae

Stellar coronae are hot ionized plasmas in the outer atmospheres of most stars. X-ray spectra that are being obtained by the Chandra and XMM-Newton observatories allow us to determine the thermal structure, densities, and dynamics of stellar coronae. We have analyzed 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.

Important Results and Discoveries:

Described the relative emission from chromospheres and coronae as a function of stellar effective temperature and age.
Computed models of M dwarf stars that include coronae consistent with the observed X-ray emission.
Showed that the relative FIP effect in stars depends on spectral type and activity.
Surveyed the forbidden coronal emission lines in ultraviolet and optical spectra and showed that their fluxes are consistent with X-ray spectra.
Obtained and analyzed multiwavelength (X-ray to optical) emission of stars during quiescence and flaring.
Reviewed the quiescent and flare X-ray emission, coronal mass ejections, and stellar-planetary interactions in the book "Host Stars and their effects on Exoplanet Atmospheres".

Papers published in refereed journals since 2000:

Tilipman, D., Vieytes, M., Linsky, J.L., Buccino, A.P., and France, K.: 2021, "Semiempirical Modeling of the Atmospheres of the M Dwarf Exoplanet Hosts GJ 832 and GJ 581", Astrophysical Journal, 909, 61
Duvvuri, G.M., Sabastian Pineda, J., Berta-Thompson, Z.K., Linsky, J.L., et al.: 2021, "Reconstructing the extreme ultraviolet emission of cool dwarfs using differential emission measure polynomials", Astrophysical Journal, 913, 30D
Linsky, J.L., Wood, B.E., Youngblood, A., Brown, A., et al.: 2020, "The Relative Emission from Chromospheres and Coronae: Dependence on Spectral Type and Age", Astrophysical Journal, 902, 3
France, K., Duvvuri, G.M., Egan, H., Linsky, J.L.,et al.: 2020, "The high-energy radiation environment around a 10 Gyr M dwarf: Habitable at last?", Astronomical Journal, 160, 237
Froning, C.S., Kowalski, A., France, K., Linsky, J.L., et al.: 2019, "The hot ultraviolet flare on the M dwarf GJ 674", Astrophysical Journal, 871, 26F
Loyd, R.OP., France, K., Youngblood, A., Schneider, C., Brown, A., Hu, R., Linsky, J.L., et al.: 2016, " The MUSCLES Treasury Survey. III. X-Ray to Infrared Spectra of 11 M and K Stars Hosting Planets", Astrophysical Journal, 824, 102
Wood, B.E. and Linsky, J.L.: 2010, "Resolving the Xi Boo binary with Chandra, and revealing the spectral type dependence of the corona 'FIP' effect", Astrophysical Journal, 717, 1279
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
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
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
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
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

Review Papers and conference papers since 2000:

Linsky, J.: 2019, "Host Stars and their Effects on Exoplanet Atmospheres", book published by Springer

Forbich, J., Guedel, M., Linsky, J.L. et al.: 2011, "The radio-X-ray relation in cool stars: Are we headed toward a divorce?", in The 16th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, ed. C.M. Johns-Krull, M.K. Browning, and A.A. West, ASP Conf. Series, 448, 455

Lillie, C., Cash, W., Arav, N., Shull, J.M., and Linsky, J.L.: 2007, "High resolution soft X-ray spectroscopy for Constellation X", SPIE 6686, 668612

Linsky, J.L., Gagne', M., Mytyk, A., McCaughren, M., and Andersen, M.: 2008, "The Eagle Nebula: Pillars of Creation, EGGs, and PMS Stars in NGC 6611", in 14th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, ed. G.T. van Belle, Astronomical Society of the Pacific Conference Series, 384, 59

Linsky, J.L., Gagne', M., Mytyk, A., McCaughren, M., and Andersen, M.: 2007, "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

Linsky, J.L.: 2004, "Summary of Cool Stars, Stellar Systems, and the Sun", powerpoint presentation

Linsky, J.L.: 2003, "X-ray coronae of stars: Recent results from Chandra", Advances in Space Research, 32, No. 6, 917

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., 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

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

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

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