FIS image header
Scholarly Interest Report
Andrea Isella
Assistant Professor
Assistant Professor of Physics and Astronomy
  • Ph.D. Physics, Astrophysics, and Applied Physics (2006) Universita' degli Studi di Milano, Milano, Italy
  • B.S. Astronomy (2003) Universita' degli Studi di Padova, Padova, Italy
Primary Department
   Department of Physics and Astronomy
Department Affiliations
  • Department of Physics and Astronomy
    Research Areas
     Galactic Astronomy and Astrophysics

    Observational study of planet formation


    During the last twenty years, astronomers have discovered more than 1500 planets outside the Solar system. These exoplanets are characterized by a striking variety of properties, such as mass, density, and orbital configuration. Most of them belong either to the “hot Jupiter” family, comprising planets with a mass similar to that of Jupiter but orbiting very close to their parent star, or to the “super Earth” family, comprising planets with a mass between 5 and 10 Earth masses. Surprisingly, the planets in our Solar system do not belong to neither of these two categories, rising the question of how common planetary systems like ours are across the cosmos.

    To investigate this question, I study the formation of planets by observing the environment where planets form, namely, the gas and dust-rich disks surrounding young stars, also known as protoplanetary disks. By mapping the spatial distribution, composition, and kinematics of the circumstellar material, I study how planets are assembled and how they interact with the protoplanetary disk. As discussed below, this investigation delivers information about the mass and orbital radius of newborn planets, it constrains the time required to form them, and reveals how the formation and evolution of planets are a↵ected by the environment and by the properties of the central star.

    Over the course of my career, I have been involved in developing millimeter-wave telescopes (the most recent effort is described in Isella et al. 2015, arXiv:1510.06444) and in using them to study planet formation. Millimeter-wave observations deliver the sharpest pictures of protoplanetary disk and are capable to unveil newborn planetary systems on spatial scales as small as 1 Astronomical Unit (AU). Among the most significant results obtained so far, I and my collaborators have found that the diversity observed in exoplanetary system might track back to the observed large spread in the distribution of gas and dust around young stars, which, in turn, is related to the mass and angular momentum of the primordial clouds from which stars, disks, and utimately planets form (Isella et al., 2009, ApJ, 701, 260). We have been among the first to discover azimuthally asymmetric large scale structures in the distribution of circumstellar material around young stars (one example of which is shown in the next page) and to interpret these features as gravitational perturbations created by planets (Isella et al., 2013, ApJ, 775, 30). Furthermore, we have developed a novel technique to measure the size of solid particles orbiting young stars. Using this technique, we have discovered that rocky planets should form preferentially in the innermost 10-20 AU where dust grains are concentrated by the aerodynamic interaction with the circumstellar gas (Isella et al., 2010, ApJ, 714, 1746; P´erez et al., 2012, 760, 17; P´erez et al. 2015, ApJ, 813, 41).


    In the last three years, we have been among the top users of the Atacama Large Millimeter Array (ALMA), a newly constructed millimeter-wave telescope capable of imaging protoplanetary disks at unprecedented sensitivity and resolution. Between 2014 and 2015, we have published 11 articles on refereed journals focusing on measuring the properties of disks perturbed by planets (see the list of publications in the CV). Among the most significant results, we have discovered that gravitational perturbations by newborn planets can cause local enhancements in the density of solid particles, which might act as a catalyst for the formation of a second generation of planets (e.g., Van der Marel et al., 2015, A&A, 579, 106; P´erez et al., 2014, ApJ, 783, 13). More recently, we have discovered that the ringed structure of the protoplanetary disk around the 1 Myr-old star HL Tau is caused by the interaction between the circumstellar material and three planets with masses comparable to that of Saturn and orbiting between 10-70 AU from the central star (Jin S. et al. 2016, ApJ, 818, 76). This result is unexpected because it contradicts current planet formation models, which predict that giant planets should form much closer to the central star, where the density of gas and dust is the highest, and on a time scale several times longer than the age of this system.

    Several ongoing research projects focus on the analysis of new exciting ALMA observations of protoplanetary disks. We have obtained observations of the HD 142527 young binary systems which reveal the complex morphology of its circumbinary disk. We have discovered ringed disks surrounding the young stars HD 163296 and TW Hydrae, which suggest the presence of newborn planets at distances ranging between 1-150 AU from the central star. HL Tau, HD 163296, and TW Hydrae are so far the only three objects in which such structures have been observed. In addition to ALMA observations, we are targeting planet forming disks at infrared and radio wavelengths to study the distribution of micron-sized and cm grains, respectively (e.g, Isella et al. 2014, ApJ, 788, 129; Benisty et al. 2015, A&A, 578, 6). All these observations, which were not possible before the construction of ALMA and of the newest high-contrast infrared cameras, enable us to directly study the formation of planetary systems, opening a completely new field in modern observations Astronomy.

    Teaching Areas
     Galactic and Extragalactic astronomy courses for undergraduate and graduate students
    Selected Publications
     Refereed articles

    L. Ricci, J. M. Carpenter, B. Fu, A. M . Hughes, S. Corder, A. Isella "ALMA observations of the debris disk around the young solar analog HD 107146." Astrophysical Journal


    M. Benisty, M., A. Juhasz, A. Boccaletti, H. Avenhaus, J. Milli, C. Thalmann, C. Dominik, P. Pinilla, E. Buenzli, A. Pohl, J.-L. Beuzit, T. Birnstiel, J. de Boer, M.  5 Bonnefoy, G. Chauvin, V. Christiaens, A. Garufi, C. Grady, T. Henning, N. Huelamo, A. Isella, M. Langlois, F. Ménard, D. Mouillet, J. Olofsson, E. Pantin, C. Pinte, L. Pueyo "“Asymmetric features in the protoplanetary disk MWC 758." Astronomy & Astrophysics


    N. van der Marel, E. van Dishoeck, S. Bruderer, L. M. Pérez, A. Isella "Gas density drops inside dust cavities of transitional disks around young stars observed with ALMA." Astrophysical Journal


    Pinilla, P.; de Boer, J.; Benisty, M.; Juhász, A.; de Juan Ovelar, M.; Dominik, C.; Avenhaus, H.; Birnstiel, T.; Girard, J. H.; Huelamo, N.; A. Isella, Milli, J., "Variability and dust filtration in the transition disk J160421.7-213028 observed in optical scattered light." Astronomy & Astrophysics


    Pérez, Laura M.; Chandler, Claire J.; A. Isella; Carpenter, John M.; Andrews, Sean M.; Calvet, Nuria; Corder, Stuartt A.; Deller, Adam T.; Dullemond, Cornelis P.; Greaves, Jane S.; Harris, Robert J.; Henning, Thomas; Kwon, Woojin; Lazio, Joseph; Linz, Hendrik; Mundy, Lee G.; Ricci, Luca; Sargent, Anneila I.; Storm, Shaye; Tazzari, Marco; Testi, Leonardo; Wilner, David J., "“Grain Growth in the Circumstellar Disks of the Young Stars CY Tau and DoAr 25." Astrophysical Journal


    A. Isella, C. J. Chandler, J. M. Carpenter, L. M. Perez, L. Ricci "Searching for Circumplanetary Disks around LkCa 15." 


    J. M. Carpenter, L. Ricci, A. Isella "An ALMA Continuum Survey of Circumstellar Disks in the Upper Scorpius OB Association." 


    J. Menu, R. van Boekel, Th. Henning, C. J. Chandler, H . Linz, M. Benisty, S. Lacour, M. Mid, C. Waelkens, S. M. Andrews, N Calvet, J. M. Carpenter, S. A. Corder, A. T. Deller, J. S. Graves, R. J. Harrins, A. Isella, W. Kwon, J. Lazio, J.-B. Le Bouquin, F. Menard, L. G. Mundy, L. M. Perez, L. Ricci, A. I. Sargent., S. Storm, L. Testi, D. J. Wilner "On the structure of the transition disk around TW Hydrae." 


    K. I. Lee, M. Fernández-López, S . Storm, L. W. Looney, L. G. Mundy, D. Segura-Cox, P. Teuben, E. Rosolowsky, H. G. Arce, E. C. Ostriker, Y. Shirley, W. Kwon, J. Kauffmann, J. J. Tobin, A. Plunkett, M. W. Pound, D. M. Salter, N. H. Volgenau, C.-Y. Chen, K. Tassis, A. Isella, R. M. Crutcher, C. F. Gammie, L. Testi "CARMA Large Area Star Formation Survey: Structure and Kinematics of Dense Gas in Serpens Main." 


    K. Zhang, A. Isella, J. M. Carpenter, G. A. Blake "Comparison of the Dust and Gas Radial Structure in the Transition Disk [PZ99] J160421.7-213028." 


    L. Perez, A. Isella, J. M. Carpenter, C. J. Chandler, "Large-scale Asymmetries in the Transitional Disks of SAO 206462 and SR 21." 


    L. Ricci., L. Testi, A. Natta, A. Sholz, I. de Gregorio-Monsalvo, A. Isella "Brown Dwarf Disks with ALMA." 


    M. Fernandez-Lopez, H. G. Arce, L. Looney, L. G. Mundy, S. Storm, P. J. Teuben, K. Lee, D. Segura-Cox, A. Isella, J. J. Tobin, E. Rosolowsky, A. Plunkett, W. Kwon, J. Kauffmann, E. Ostriker, K. Tassis, Y. L. Shirley, M. Pound "CARMA Large Area Star Formation Survey: Observational Analysis of Filaments in the Serpens South Molecular Cloud." 


    P . Pinilla, M. Benisty, T. Birnstiel, L. Ricci, A. Isella, A. Natta "Millimetre spectral indices of transition disks and their relation to the cavity radius." 


    S. M. Andrews, C. J. Chandler, A. Isella, T. Birnstiel, K. A. Rosenfeld, D. J. Wilner, L. M. Perez, L. Ricci, J. M. Carpenter, N. Calvet, S. Corder, A. T. Deller, C. P. Dullemond, J. S. greaves, R. J. Harris, Th. Henning, W. Kwon, J., Lazio, H. Linz, L. G. Mundy, A. I. Sargent, S. Storm, L. Testi "“Resolved Multifrequency Radio Observations of GG Tau." 


    S. Storm, L. G. Mundy, M. Fernandez-Lopez, K. I. Lee, W. L. Looney, P. J. Teuben, E. Rosolowsky, H. G. Arce, E. C. Ostriker, D. Segura-Cox, M. W. Pound, D. M. Salter, N. H. Volgenau, Y. Shirley, C.-Y. Chen, H. Gong, A. L. Plunkett, J. J. Tobin, W. Kwon, J., A. Isella, J. Kauffmann, K. Tassis, R. M. Crutcher, C. Gammie, L. Testi "CARMA Large Area Star Formation Survey: Project Overview with Analysis of Dense Gas Structure and Kinematics in Barnard 1." 


    Carilli, C. L.; McKinnon, M.; Ott, J.; Beasley, A.; Isella, A.; Murphy, E.; Leroy, A.; Casey, C.; Moullet, A.; Lacy, M.; Hodge, J.; Bower, G.; Demorest, P.; Hull, C.; Hughes, M.; di Francesco, J.; Narayanan, D.; Kent, B.; Clark, B.; Butler, B. "Next Generation Very Large Array Memo No. 5: Science Working Groups -- Project Overview." arXiv: 1510.06438


    Isella, Andrea; Hull, Charles L. H.; Moullet, Arielle; Galván-Madrid, Roberto; Johnstone, Doug; Ricci, Luca; Tobin, John; Testi, Leonardo; Beltran, Maite; Lazio, Joseph; Siemion, Andrew; Liu, Hauyu Baobab; Du, Fujun; Öberg, Karin I.; Bergin, Ted; Caselli, Paola; Bourke, Tyler; Carilli, Chris; Perez, Laura; Butler, Bryan; de Pater, Imke; Qi, Chunhua; Hofstadter, Mark; Moreno, Raphael; Alexander, David; Williams, Jonathan; Goldsmith, Paul; Wyatt, Mark; Loinard, Laurent; Di Francesco, James; Wilner, David; Schilke, Peter; Ginsburg, Adam; Sánchez-Monge, Álvaro; Zhang, Qizhou; Beuther, Henrik, "Next Generation Very Large Array Memo No. 6, Science Working Group 1: The Cradle of Life." arXiv:1510.06444

     Book chapters

    Testi, L.; Birnstiel, T.; Ricci, L.; Andrews, S.; Blum, J.; Carpenter, J.; Dominik, C.; Isella, A.; Natta, A.; Williams, J. P.; Wilner, D. J. "Dust Evolution in Protoplanetary Disks." Protostars and Planets VI

     Conference Paper

    "Study planet formation with future radio telescopes." U.S. Radio/Millimeter/ Submillimeter Science Futures in the 2020s, Chicago. (December, 2015)

     Invited Papers

    "J160421.7-213028: A remarkably boring disk." Transitional Disk Workshop, Leiden, The Netherlands. (March, 2015)

     Invited Talks

    "From Circumstellar Disks to Extrasolar Planets: Observational Insights." IAUS 315, General Assembly of the International Astronomical Society, Honolulu, Hawaii. (August, 2015)


    "Report from the NGVLA Cradle of Life Science Working Group." American Astronomical Society meeting, Seattle. (January, 2015)


    "What do observations tell us about planet formation." colloquium at the Department of Earth Science,, Rice University, Houston. (September, 2015)


    "ALMA Observations of Circumstellar Discs."


    "From Circumstellar Disks to Extrasolar Planets: Observational Insights."


    "From Circumstellar Disks to Extrasolar Planets: Observational Insights."


    "From Circumstellar Disks to Extrasolar Planets: Observational Insights."


    "Analysis of the Serpens South Filamentary Cloud: CLASSy Results."


    "Dendrogram Analysis of Large-Area CARMA Images in Perseus: the Dense Gas in NGC 1333, Barnard 1, and L1451."


    "First images from the PIONIER/VLTI optical interferometry imaging survey of Herbig Ae/Be stars."


    "Imaging Young Stellar Objects with VLTi/PIONIER."


    "Imaging and modeling SSTTau J042021+281349, a new prototypical edge-on protoplanetary disk."


    "Kinematics and Temperature Structures of Filaments in Serpens Main and Serpens South."


    "Panchromatic imaging and modeling of SSTtau J042021+281349: A new prototypical edge-on protoplanetary disk."


    "Resolved Multifrequency Radio Observations of GG Tau."


    "TW Hydrae: multiwavelength interferometry of a transition disk."


    "The Structure of Dense Gas in Perseus and Serpens: CLASSy Results."


    "[PZ99] J160421.7-213028, a transition disk with ring shaped dust accumulation."

     Seminar Speaker

    "From Circumstellar Disks to Extrasolar Planets: Observational Insights." Astronomy colloquium, Los Alamos National Laboratory, NM,. (May, 2015)

    Supervised Theses & Dissertations
     Sal Tijerina, BS MODELLING OF PLANET FORMATION IN THE EARLY SOLAR SYSTEM. (2015) (Thesis or Dissertation Director)