FORJADOS DE LA CASA DE INFORMACIÓN
EXIGENCIAS BÁSICAS DE SEGURIDAD ESTRUCTURAL ( DB SE) ANÁLISIS ESTRUCTURAL Y DIMENSIONADO
325.01 — Dust Spreading in Debris Discs: Do Small Grains Cling on to Their Birth Environment?
Nicole Pawellek1,2; Attila Moór2; Ilaria Pascucci1,3;
Alexander Krivov4
1 Max-Planck-Institut für Astronomie (Heidelberg, Germany) 2 Konkoly Observatory (Budapest, Hungary)
3 Lunar and Planetary Laboratory, University of Arizona (Tuscon, Arizona, United States)
4 Astrophysikalisches Institut und Universitätssternwarte (Jena, Germany)
Debris discs are dusty belts of planetesimals around main-sequence stars, similar to the asteroid and Kuiper belts in our solar system. The planetesimals cannot be observed directly, yet they produce de- tectable dust in mutual collisions. Observing the
dust, we can try to infer properties of invisible plan- etesimals. Here we address the question of what is the best way to measure the location of outer plan- etesimal belts that encompass extrasolar planetary systems. A standard method is using resolved im- ages at mm-wavelengths, which reveal dust grains with sizes comparable to the observational wave- length. Smaller grains seen in the infrared (IR) are subject to several non-gravitational forces that drag them away from their birth rings, and so may not closely trace the parent bodies. In this study, we examine whether imaging of debris discs at shorter wavelengths might enable determining the spatial location of the exo-Kuiper belts with sufficient accu- racy. We find that around M-type stars the dust best visible in the mid-IR is efficiently displaced inward from their birth location by stellar winds, causing the discs to look more compact in mid-IR images than they actually are. However, around earlier-type stars where the majority of debris discs is found, discs are still the brightest at the birth ring location in the mid- IR regime. Thus, sensitive IR facilities with good an- gular resolution, such as MIRI on JWST, will enable tracing exo-Kuiper belts in nearby debris disc sys- tems.
325.02 — Testing the Paradigm of Asteroidal Dust around White Dwarfs with the Prototype
Ted von Hippel1; Judi Provencal3; Jay Farihi4; Scot
Kleinman2; Gilles Fontaine5; Jim Pringle6
1 Embry Riddle Aeronautical University (Daytona Beach, Florida, United States)
2 Gemini Observatory (Hilo, Hawaii, United States) 3 University of Delaware (Newark, Delaware, United States) 4 University College London (London, United Kingdom) 5 University of Montreal (Montreal, Quebec, Canada) 6 University of Cambridge (Cambridge, United Kingdom)
At least one quarter of all white dwarfs are ac- tively accreting debris from planetesimals or plane- tary fragments. The prototype system G29-38 was discovered at the IRTF in 1987. Yet despite the in- tervening decades and a complete paradigm shift in the explanation from interstellar material to exoplan- etary debris, there remain fundamental questions. The common assumption now is that the dust debris is in a circumstellar disk, yet if so the geometry and vertical optical depth are observationally degenerate. Optically thin and thick cases vary in disk mass — and hence parent body mass — by orders of mag- nitude. The parent body masses have far-reaching implications for planetary system architecture and long-term dynamics. We report on our work to break this degeneracy and even to test whether the dust is
in a disk at all or some other geometrical distribution based on the fact that the prototype system contains a well-studied, pulsating star. Using MORIS and SpeX at the NASA 3-meter Infrared Telescope Facil- ity, we simultaneously monitored the optical stellar pulsations and the ensuing infrared dust response. These observations can distinguish among a range of dust configurations, based on the observed infrared response to the known geometry of the optical pul- sations.
325.04 — A survey for resolved debris disks in the Sco-Cen association with the Gemini Planet Im- ager
Jenny Patience1; Justin Hom1; Thomas M. Esposito2;
Paul Kalas3; Marshall D. Perrin7; Elisabeth Matthews4;
Pauline Arriaga6; Christine Chen7; Johan Mazoyer8;
Maxwell A. Millar-Blanchaer8; Stanimir Metchev5;
Brenda Matthews9; Michael P. Fitzgerald6; Schuyler
Wolff10; Gaspard Duchene2
1 Earth and Space Exploration, Arizona State University (Tempe, Arizona, United States)
2 University of Leiden (Leiden, Netherlands)
3 Astronomy, UC Berkeley (Berkeley, California, United States) 4 University of California, Berkeley (Berkeley, California, United States)
5 MIT (Somerville, Massachusetts, United States)
6 Physics & Astronomy, University of Western Ontario (London, Ontario, Canada)
7 UCLA (Los Angeles, California, United States)
8 Space Telescope Science Institute (Baltimore, Maryland, United States)
9 JPL (Pasadena, California, United States) 10 HIA (Victoria, British Columbia, Canada)
With the Gemini Planet Imager (GPI), we are con- ducting a survey of debris disk systems in the Scorpious-Centaurus OB association. Each target was observed in the polarimetry mode of GPI which is specifically designed for spatially-resolved, high- contrast observations of debris disks. A subset of the targets was also observed in the spectroscopic mode of GPI, covering the same H-band as the po- larimetry mode data. The target sample consists of a complete set of 28 early-type A and F stars lo- cated within the Upper Centaurus Lupus and Lower Centaurus Crux regions of Sco-Cen that are bright enough for GPI observations and exhibit the high- est Spitzer-detected infrared excesses, with values of LIR/Lstarabove 2.5×10−4. Overall goals of the ongo-
ing survey include exploring the range of debris disk properties around stars of similar age and formation environment, placing constraints on disk geometric properties and the potential dynamical signatures of
planets. Of the systems observed thus far, 80 per- cent have been spatially resolved. Among the newly- resolved systems, the majority have close to an edge- on geometry, one system shows a ring structure and another disk exhibits significant asymmetry, possi- bly indicating the presence of a substellar companion gravitationally interacting with the debris disk.