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Andrea Isella
Assistant Professor
Assistant Professor of Physics and Astronomy
e-mail:[email protected]
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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
Websites
planetformation.rice.edu
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."
Articles
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
Presentations
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."
Posters
"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 edgeon 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)