Absorption Line Spectroscopic Studies of the Local Interstellar Medium

Warm (5,000-10,000 K) gas in the interstellar medium is seen only in isolated clouds that can be identified by their kinematics, temperatures, and metal depletions on to grains. High resolution HST and FUSE spectra covering the 912-3000 A region contain many absorption lines formed in warm clouds. The Sun is located just inside one such cloud, the Local Interstellar Cloud (LIC), and within 100 pc of the Sun there at least 14 other clouds with different kinematic and physical properties. We are building a three-dimensional model of the warm gas clouds within 100 pc of the Sun and developing models for the ionization balance of these clouds. See the Webpage of the Colorado Model of the Local Interstellar Cloud. A view of the LIC looking down from the North Galactic Pole showing that the Sun (located at 0,0) lies barely inside the LIC.

Research Objectives:

• Model the structure and kinematics of warm clouds in the interstellar medium out to about 100 pc.
• Determine the physical properties (temperature, density, and ionization state) of warm clouds in the local interstellar medium. Study the inhomogeneity and pressure equilibrium or non-equilibrium between warm clouds and the outer heliosphere.
• Determine the chemical abundances and depletions of warm clouds in the local interstellar medium.
• Study the interaction of stellar winds with the local ISM that forms hydrogen walls and astrospheres around stars.

Important Results and Discoveries:

• Discovered the hydrogen wall in the heliosphere produced by charge exchange between inflowing neutral hydrogen and heliosphere protons.
• Discovered hydrogen walls in the astrospheres of many stars.
• Developed an empirical three-dimensional model of the local interstellar medium in the form of 15 kinematic clouds with different properties.
• Identified inhomogeneous thermal and turbulent properties in the Local Interstellar Cloudl
• Proposed the Stromgren sphere model of the Local Cavity with temperatures of 10,000 K rather than 1,000,000 K.
• Discovered that the helioisphere is at the outer edge of the Local Interstellar Cloud and will enter the G cloud in less than 2,000 years.
• Proposed that scintillation of quasar radio emission is due to turbulence where neaby interstellar clouds interact.
• Proposed a three dimensional morphological model of the Local Interstellar Cloud.

Papers in Refereed Journals since 2000:

• Linsky, J.L. & Redfield, S.: 2023, "Creating a new paradigm for the local interstellar medium - a perspective", Frontiers in Astronomy and Space Sciences, 10, 1019589
• Linsky, J.L. and Moebius, E.: 2023, "Are the Heliosphere, Very Local Interstellar Medium, and Local Cavity in Pressure Balance with Galactic Gravity?", Astrophysiocal Journal, 942, 45
• Mayyasi, M., Quemerais, E., Katushkina, O., Linsky, J.L., et al. 2022, "Using Lyman-alpha to probe the interior and edges of the heliosphere", Frontiers in Astronomy and Space Sciences, 9, 1063981,
• Swaczyna, P., Schwadron, N.A., Moebius, E., Linsky, J.L., et al. 2022, "Mixing Interstellar Clouds Surrounding the Sun", Astrophysical Journal Letters, 937, L32
• Linsky, J.L., Redfield, S., Ryder, D., and Chasan-Taber, A.: 2022, "Inhomogeneity within Local Interstellar Clouds", Astronomical Journal, 164, 106
• Linsky, J.L., Redfield, S., Ryder, D., Moebius, E.: 2022 "Inhomogeneity in the Local ISM and its Relation to the Heliosphere", Space Science Reviews, 218, 16
• Zank, G.P., Sterken, V., Giacalone, J., Linsky, J.L., et al. 2022, "The Early History of Heliospheric Science and the Spacecraft That Made It Possible" Space Science Reviews, 218, 34
• Linsky, J.L., and Redfield, S.: 2021, "Could the Local Cavity be an Irregularly Shaped Strömgren Sphere?", Astrophysical Journal, 920, 75
• Linsky, J.L., Redfield, S., and Tilipman, D.: 2019, "The Interface between the Outer Heliosphere and the Inner Local ISM: Morphology of the Local Interstellar Cloud, Its Hydrogen Hole, Strömgren Shells, and 60Fe Accretion", Astrophysical Journal, 886, 41
• Edelman, E., Redfield, S., Linsky, J.L., Wood, B.E., Muller, H.: 2019, " Properties of the Interstellar Medium along Sight Lines to Nearby Planet-hosting Stars", Astrophysical Journal, 880, 117
• Zachary, J., Redfield, S., Linsky, J.L., and Wood, B.E.: 2018, "Measuring the Local ISM along the Sight Lines of the Two Voyager Spacecraft with HST/STIS", Astrophysical Journal, 859, 42
• Linsky, J.L., Redfield, S., and Schwarz, M.: 2017, "Visualizing the three-dimensional structure of the local interstellar medium and possible physical causes of this structure", Open Access Journal of Physics: Conference Series, to appear
• Redfield, S. and Linsky, J.L.: 2015, "Evaluating the morphology of the local interstellar medium: Using new data to distinguish between multiple discrete clouds and a contimuous medium", Astrophysical Journal, 822, 125
• Malamut, C., Redfield, S., Linsky, J.L., Wood, B.E., and Ayres, T.R.: 2014, "The structure of the local interstellar medium. VI. New MgII, FeII, and MnII observations toward stars within 100 pc", Astrophysical Journal, 787, 75
• Linsky, J.L.: 2011, "Voyagers of Discovery", Science 324, 1647
• Linsky, Jeffrey L., Rickett, Barney J., and Redfield, Seth: 2008, "The Origin of Radio Scintillation in the Local Interstellar Medium", Astrophysical Journal, 675, 413
• Redfield, Seth and Linsky, Jeffrey L.: 2008, "The Structure of the Local Interstellar Medium. IV. Dynamics, Morphology, Physical Properties, and Implications of Cloud-Cloud Interactions", Astrophysical Journal, 673, 283
• Redfield, S., and Linsky, J.L.: 2004, "The structure of the Local Interstellar Medium. III. Temperature and turbulence", Astrophysical Journal, 613, 1004
• Redfield, S., and Linsky, J.L.: 2004, "The structure of the Local Interstellar Medium. II. Observations of D I, C II, N I, O I, Al II, and Si II toward stars within 100 parsecs", Astrophysical Journal, 602, 776
• Wood, B.E., Redfield, S., Linsky, J.L., and Sahu, M.S.: 2002, "Elemental abundances and ionization states within the Local Interstellar Cloud derived from HST and FUSE observations of the Capella line of sight", Astrophysical Journal, 581, 1168
• Redfield, S., and Linsky, J.L.: 2002, "The structure of the Local Interstellar Medium. I. High-resolution observations of Fe II, Mg II, and CaII toward stars within 100 parsecs", Astrophysical Journal Supplement Series, 139, 439
• Redfield, S., and Linsky, J.L.: 2001, "Microstructure of the Local Interstellar Cloud and the identification of the Hyades Cloud", Astrophysical Journal, 551, 413
• Moos, H.W. et al (including Linsky, J.L.), 2000: "Overview of the Far Ultraviolet Explorer Mission", Astrophysical Journal Letters, 538, L1
• Jenkins, E.B., et al (including Linsky, J.L.), 2000, "The ionization of the local interstellar medium as revealed by FUSE observations of N, O, and Ar toward white dwarf stars", Astrophysical Journal Letters, 538, L81
• Linsky, J.L., Redfield, S., Wood, B.E., and Piskunov, N.: 2000, "The three dimensional structure of the warm local interstellar medium. I. Methodology", Astrophysical Journal, 528, 756
• Redfield, S., and Linsky, J.L.,: 2000, "The three dimensional structure of the warm local interstellar medium. II. The Colorado model of the local interstellar cloud (LIC)", Astrophysical Journal, 534, 825
• Wood, B.E., Linsky, J.L., and Zank, G.P.: 2000, "Heliospheric, astrospheric, and interstellar Lyman-alpha absorption toward 36 Oph", Astrophysical Journal, 537, 304
• Wood, B.E., Ambruster, C.W., Brown, A., and Linsky, J.L.: 2000, "The MgII and Lyman Alpha lines of nearby K dwarfs: Interstellar medium components and flux measurements", Astrophysical Journal, 542, 411

Review and Conference Papers since 2000:

• Linsky, J.L., Redfield, S., Ryder, D., and Moebius, E.: 2022, "Inhomogeneity in the Local ISM and its Relation to the Heliosphere", Space Sciences Reviews, 218, 16L
• Zank, G.P., Sterken, V., Giacalone, J., Linsky, J.L., etc.: 2022: "The early history of heliospheric science and the spacecraft that mde it possible", Space Science Reviews, 218, 34Z
• Linsky, J.L.: 2021, "Ultraviolet investigations of the interstellar medium from astrospheres to the local cavity", chapter 4 in Ultraviolet astronomy and the quest for the origin of life, ed. Gomez de Castro, A. (Elsevier)
• Linsky, J.L., Redfield, S., Wood, B.E.: 2020, "New results concerning the environment of the heliosphere, nearby interstellar clouds, and physical processes in the inter-cloud medium", J. Physics Conf. Series, 1620, 012010
• Linsky, J.L. and Redfield, S.: 2015, "What is the morphology of the local interstellar medium and its importance for the GAIA era?", Memorie della Societa Astronomica Italiana, 86, 606
• Linsky, J.L. and Redfield, S.: 2014, "The local ISM in three dimensions: kinematics, morphology and physical properties", Astrophysics and Space Science, 354, 29
• Linsky, J.L.: 2011, "Understanding physical processes in the diffuse ISM using high-resolution UV spectroscopy", Astrophysical and Space Sciences, 335, 177
• Linsky, J.L. and Redfield, S.: 2009, "Structure, dynamics, and physical properties of the warm LISM within the Local Bubble", in The Local Bubble and Beyond II, ed. K.D. Kuntz, R.K. Smith, and S.L. Snowden, AIP Conference Proceedings 1156, 174
• Linsky, J.L.: 2009, "Results of the ISSI workshop 'From the Outer Heliosphere to the Local Bubble: Comparison of New Observations with Theory", in The Local Bubble and Beyond II, ed. K.D. Kuntz, R.K. Smith, and S.L. Snowden, AIP Conference Proceedings 1156, 184
• Frisch, P.C., Bzowski, M., Izmodenov, V., Kruger, H. Linsky, J.L. et al.: 2009, "The Galactic environment of the Sun: Interstellar material inside and outside of the heliospher":, Space Science Reviews, 146, 235
• Linsky, J.L., Mobius, E., Izmodenov,V.V., and von Steiger,R. (eds.): 2009, "From the Outer Heliosphere to the Local Bubble", Space Sciences Reviews, 143
• Linsky, Jeffrey L.: 2009, "Understanding Physical Processes in the Diffuse Interstellar Medium Using High-Resolution UV Spectroscopy", poster at the Beyond JWST: the Next Steps in UV-Optical-NIR Astronomy"
• Linsky, Jeffrey L.: 2009, "Summary of the first NUVA conference on Space Astronomy: the UV window to the Universe", Astrophysics and Space Science, 320, 3
• Linsky, Jeffrey L.: 2009, "Solving the Mysteries of the Diffuse Interstellar Medium with High-Resolution Spectroscopy", Astrophysics and Space Science, 320, 85
• Redfield, S., Wood, B.E., and Linsky, J.L.: 2004, "Physical structure of the local interstellar medium",Advances in Space Research, 34, 41
• Linsky, J.L. and Redfield, S.: 2007, "Structure of the local ISM", in SINS - Small Ionized and Neutral Structures in the Diffuse Interstellar Medium", ed. M. Haverkorn and W.M. Goss, ASP Conf. Series, 365, 219
• Linsky, J.L.: 2002, "Constructing physically realistic models of the interstellar gas: Start with understanding the physics of the local ISM", in Hubble Science Legacy Workshop, ed. K. Sembach, et al, ASP Conf. Series, 291, 188
• Linsky, J.L., Redfield, S., and Wood, B.E.: 2000, "The warm local ISM: structure, properties, and theory", invited talk at the Fourth Tetons Summer Conference: Galactic Structure, Stars and the Interstellar Medium, Jackson Hole WY, May 28-June 1, 2000, ASP 231, 337
• Linsky, J.L., Redfield, S., and Wood, B.: 2000, "Components of the local interstellar medium", invited talk at IAU Symposium 203, Recent Insights in to the Physics of the Sun and Heliosphere, Manchester England, Aug 7-11, 2000, Astronomical Society of the Pacific Conference Series, 200, 595