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A background galaxy in the field of the beta Pic debris disk  [PDF]
S. Regibo,B. Vandenbussche,C. Waelkens,B. Acke,B. Sibthorpe,M. Nottebaere,K. Voet,J. Di Francesco,M. Fridlund,W. K. Gear,R. J. Ivison,G. Olofsson
Physics , 2012, DOI: 10.1051/0004-6361/201118631
Abstract: Herschel images in six photometric bands show the thermal emission of the debris disk surrounding beta Pic. In the three PACS bands at 70 micron, 100 micron and 160 micron and in the 250 micron SPIRE band, the disk is well-resolved, and additional photometry is available in the SPIRE bands at 350 micron and 500 micron, where the disk is only marginally resolved. The SPIRE maps reveal a blob to the southwest of beta Pic, coinciding with submillimetre detection of excess emission in the disk. We investigated the nature of this blob. Our comparison of the colours, spectral energy distribution and size of the blob, the disk and the background sources shows that the blob is most likely a background source with a redshift between z =1.0 and z = 1.6.
$β$ Pictoris' inner disk in polarized light and new orbital parameters for $β$ Pictoris b  [PDF]
Maxwell A. Millar-Blanchaer,James R. Graham,Laurent Pueyo,Paul Kalas,Rebekah I. Dawson,Jason Wang,Marshall Perrin,Dae-Sik Moon,Bruce Macintosh,S. Mark Ammons,Travis Barman,Andrew Cardwell,Christine H. Chen,Eugene Chiang,Jeffrey Chilcote,Tara Cotten,Robert J. De Rosa,Zachary H. Draper,Jennifer Dunn,Gaspard Duchêne,Thomas M. Esposito,Michael P. Fitzgerald,Katherine B. Follette,Stephen J. Goodsell,Alexandra Z. Greenbaum,Markus Hartung,Pascale Hibon,Sasha Hinkley,Patrick Ingraham,Rebecca Jensen-Clem,Quinn Konopacky,James E. Larkin,Douglas Long,Jér?me Maire,Franck Marchis,Mark S. Marley,Christian Marois,Katie M. Morzinski,Eric L. Nielsen,David W. Palmer,Rebecca Oppenheimer,Lisa Poyneer,Abhijith Rajan,Fredrik T. Rantakyr?,Jean-Baptiste Ruffio,Naru Sadakuni,Leslie Saddlemyer,Adam C. Schneider,Anand Sivaramakrishnan,Remi Soummer,Sandrine Thomas,Gautam Vasisht,David Vega,J. Kent Wallace,Kimberly Ward-Duong,Sloane J. Wiktorowicz,Schuyler G. Wolff
Physics , 2015, DOI: 10.1088/0004-637X/811/1/18
Abstract: We present $H$-band observations of $\beta$ Pic with the Gemini Planet Imager's (GPI's) polarimetry mode that reveal the debris disk between ~0.3" (~6 AU) and ~1.7" (~33 AU), while simultaneously detecting $\beta$ Pic $b$. The polarized disk image was fit with a dust density model combined with a Henyey-Greenstein scattering phase function. The best fit model indicates a disk inclined to the line of sight ($\phi=85.27{\deg}^{+0.26}_{-0.19}$) with a position angle $\theta_{PA}=30.35{\deg}^{+0.29}_{-0.28}$ (slightly offset from the main outer disk, $\theta_{PA}\approx29{\deg}$), that extends from an inner disk radius of $23.6^{+0.9}_{-0.6}$ AU to well outside GPI's field of view. In addition, we present an updated orbit for $\beta$ Pic $b$ based on new astrometric measurements taken in GPI's spectroscopic mode spanning 14 months. The planet has a semi-major axis of $a=9.2^{+1.5}_{-0.4}$AU, with an eccentricity $e\leq 0.26$. The position angle of the ascending node is $\Omega=31.75{\deg}\pm0.15$, offset from both the outer main disk and the inner disk seen in the GPI image. The orbital fit constrains the stellar mass of $\beta$ Pic to $1.60\pm0.05 M_{\odot}$. Dynamical sculpting by $\beta$ Pic $b$ cannot easily account for the following three aspects of the inferred disk properties: 1) the modeled inner radius of the disk is farther out than expected if caused by $\beta$ Pic b; 2) the mutual inclination of the inner disk and $\beta$ Pic $b$ is $4{\deg}$, when it is expected to be closer to zero; and 3) the aspect ratio of the disk ($h_0 = 0.137^{+0.005}_{-0.006}$) is larger than expected from interactions with $\beta$ Pic $b$ or self-stirring by the disk's parent bodies.
Molecular Gas Clumps from the Destruction of Icy Bodies in the $β$ Pictoris Debris Disk  [PDF]
W. R. F. Dent,M. C. Wyatt,A. Roberge,J. -C. Augereau,S. Casassus,S. Corder,J. S. Greaves,I. de Gregorio-Monsalvo,A. Hales,A. P. Jackson,A. Meredith Hughes,A. -M. Lagrange,B. Matthews,D. Wilner
Physics , 2014, DOI: 10.1126/science.1248726
Abstract: Many stars are surrounded by disks of dusty debris formed in the collisions of asteroids, comets and dwarf planets. But is gas also released in such events? Observations at submm wavelengths of the archetypal debris disk around $\beta$ Pictoris show that 0.3% of a Moon mass of carbon monoxide orbits in its debris belt. The gas distribution is highly asymmetric, with 30% found in a single clump 85AU from the star, in a plane closely aligned with the orbit of the inner planet, $\beta$ Pic b. This gas clump delineates a region of enhanced collisions, either from a mean motion resonance with an unseen giant planet, or from the remnants of a collision of Mars-mass planets.
A Resolved Millimeter Emission Belt in the AU Mic Debris Disk  [PDF]
David J. Wilner,Sean M. Andrews,Meredith A. MacGregor,A. Meredith Hughes
Physics , 2012, DOI: 10.1088/2041-8205/749/2/L27
Abstract: We present imaging observations at 1.3 millimeters of the debris disk surrounding the nearby M-type flare star AU Mic with beam size 3 arcsec (30 AU) from the Submillimeter Array. These data reveal a belt of thermal dust emission surrounding the star with the same edge-on geometry as the more extended scattered light disk detected at optical wavelengths. Simple modeling indicates a central radius of ~35 AU for the emission belt. This location is consistent with the reservoir of planetesimals previously invoked to explain the shape of the scattered light surface brightness profile through size-dependent dust dynamics. The identification of this belt further strengthens the kinship between the debris disks around AU Mic and its more massive sister star beta Pic, members of the same ~10 Myr-old moving group.
On the unusual gas composition in the Beta Pictoris debris disk  [PDF]
Ji-Wei Xie,Alexis Brandeker,Yanqin Wu
Physics , 2012, DOI: 10.1088/0004-637X/762/2/114
Abstract: The metallic gas associated with the Beta Pic debris disk is not believed to be primordial, but arises from the destruction of dust grains. Recent observations have shown that carbon and oxygen in this gas are exceptionally overabundant compared to other elements, by some 400 times. We study the origin of this enrichment under two opposing hypothesis, preferential production, where the gas is produced with the observed unusual abundance (as may happen if gas is produced by photo-desorption from C/O-rich icy grains), and preferential depletion, where the gas evolves to the observed state from an original solar abundance (if outgassing occurs under high-speed collisions) under a number of dynamical processes. We include ... ... We find ... ...
Rings in the Planetesimal Disk of Beta Pic  [PDF]
P. Kalas,J. Larwood,B. A. Smith,A. Schultz
Physics , 2000, DOI: 10.1086/312494
Abstract: The nearby main sequence star Beta Pictoris is surrounded by an edge-on disk of dust produced by the collisional erosion of larger planetesimals. Here we report the discovery of substructure within the northeast extension of the disk midplane that may represent an asymmetric ring system around Beta Pic. We present a dynamical model showing that a close stellar flyby with a quiescient disk of planetesimals can create such rings, along with previously unexplained disk asymmetries. Thus we infer that Beta Pic's planetesimal disk was highly disrupted by a stellar encounter in the last hundred thousand years.
Herschel HIFI observations of ionised carbon in the β Pictoris debris disk  [PDF]
G. Cataldi,A. Brandeker,G. Olofsson,B. Larsson,R. Liseau,J. Blommaert,M. Fridlund,R. Ivison,E. Pantin,B. Sibthorpe,B. Vandenbussche,Y. Wu
Physics , 2013, DOI: 10.1051/0004-6361/201323126
Abstract: Context: The dusty debris disk around the $\sim$20 Myr old main-sequence A-star {\beta} Pictoris is known to contain gas. Evidence points towards a secondary origin of the gas as opposed to being a direct remnant form the initial protoplanetary disk, although the dominant gas production mechanism is so far not identified. The origin of the observed overabundance of C and O compared to solar abundances of metallic elements, e.g. Na and Fe, is also unclear. Aims: Our goal is to constrain the spatial distribution of C in the disk, and thereby the gas origin and its abundance pattern. Methods: We used the HIFI instrument onboard Herschel to observe and spectrally resolve CII emission at 158 $\mu$m from the {\beta} Pic debris disk. Assuming Keplerian rotation, we use the spectrally resolved line profile to constrain the spatial distribution of the gas. Results: We show that most of the gas is located around $\sim$100 AU or beyond. We estimate a total C gas mass of $1.3\times10^{-2}$ M$_\oplus$. The data suggest that more gas is located on the southwest side of the disk than on the northeast side. The data are consistent with the hypothesis of a well-mixed gas (constant C/Fe ratio throughout the disk). Assuming instead a spatial profile expected from a simplified accretion disk model, we found it to give a significantly worse fit to the observations. Conclusions: Since the bulk of the gas is found outside 30 AU, we argue that the cometary objects known as "falling evaporating bodies" are unlikely to be the dominant source of gas; production from grain-grain collisions or photodesorption seems more likely. The incompatibility of the observations with a simplified accretion disk model could favour a preferential depletion explanation for the overabundance of C and O. More stringent constraints on the spatial distribution will be available from ALMA observations of CI at 609 $\mu$m.
The SEEDS Direct Imaging Survey for Planets and Scattered Dust Emission in Debris Disk Systems  [PDF]
Markus Janson,Timothy D. Brandt,Amaya Moro-Martin,Tomonori Usuda,Christian Thalmann,Joseph C. Carson,Miwa Goto,Thayne Currie,M. W. McElwain,Yoichi Itoh,Misato Fukagawa,Justin Crepp,Masayuki Kuzuhara,Jun Hashimoto,Tomoyuki Kudo,Nobuhiko Kusakabe,Lyu Abe,Wolfgang Brandner,Sebastian Egner,Markus Feldt,Carol A. Grady,Olivier Guyon,Yutaka Hayano,Masahiro Hayashi,Saeko Hayashi,Thomas Henning,Klaus W. Hodapp,Miki Ishii,Masanori Iye,Ryo Kandori,Gillian R. Knapp,Jungmi Kwon,Taro Matsuo,Shoken Miyama,Jun-Ichi Morino,Tetsuro Nishimura,Tae-Soo Pyo,Eugene Serabyn,Takuya Suenaga,Hiroshi Suto,Ryuji Suzuki,Yasuhiro Takahashi,Michihiro Takami,Naruhisa Takato,Hiroshi Terada,Daego Tomono,Edwin L. Turner,Makoto Watanabe,John Wisniewski,Toru Yamada,Hideki Takami,Motohide Tamura
Physics , 2013, DOI: 10.1088/0004-637X/773/1/73
Abstract: Debris disks around young main-sequence stars often have gaps and cavities which for a long time have been interpreted as possibly being caused by planets. In recent years, several giant planet discoveries have been made in systems hosting disks of precisely this nature, further implying that interactions with planets could be a common cause of such disk structures. As part of the SEEDS high-contrast imaging survey, we are surveying a population of debris disk-hosting stars with gaps and cavities implied by their spectral energy distributions, in order to attempt to spatially resolve the disk as well as to detect any planets that may be responsible for the disk structure. Here we report on intermediate results from this survey. Five debris disks have been spatially resolved, and a number of faint point sources have been discovered, most of which have been tested for common proper motion, which in each case has excluded physical companionship with the target stars. From the detection limits of the 50 targets that have been observed, we find that beta Pic b-like planets (~10 Mjup planets around G--A-type stars) near the gap edges are less frequent than 15--30%, implying that if giant planets are the dominant cause of these wide (27 AU on average) gaps, they are generally less massive than beta Pic b.
The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets Around Debris Disk Stars  [PDF]
Zahed Wahhaj,Michael C. Liu,Eric L. Nielsen,Beth A. Biller,Thomas L. Hayward,Laird M. Close,Jared R. Males,Andrew Skemer,Christ Ftaclas,Mark Chun,Niranjan Thatte,Matthias Tecza,Evgenya L. Shkolnik,Marc Kuchner,I. Neill Reid,Elisabete M. de Gouveia Dal Pino,Silvia H. P. Alencar,Jane Gregorio-Hetem,Alan Boss,Douglas N. C. Lin Douglas W. Toomey
Physics , 2013, DOI: 10.1088/0004-637X/773/2/179
Abstract: We have completed a high-contrast direct imaging survey for giant planets around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign. We achieved median H-band contrasts of 12.4 mag at 0.5" and 14.1 mag at 1" separation. Follow-up observations of the 66 candidates with projected separation < 500 AU show that all of them are background objects. To establish statistical constraints on the underlying giant planet population based on our imaging data, we have developed a new Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constrain the planet population. Our formalism allows us to include in our analysis the previously known Beta Pictoris and the HR 8799 planets. Our results show at 95% confidence that <13% of debris disk stars have a >5MJup planet beyond 80 AU, and <21% of debris disk stars have a >3MJup planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly-imaged planets as d^2N/dMda ~ m^alpha a^beta, where m is planet mass and a is orbital semi-major axis (with a maximum value of amax). We find that beta < -0.8 and/or alpha > 1.7. Likewise, we find that beta < -0.8 and/or amax < 200 AU. If we ignore the Beta Pic and HR 8799 planets (should they belong to a rare and distinct group), we find that < 20% of debris disk stars have a > 3MJup planet beyond 10 AU, and beta < -0.8 and/or alpha < -1.5. Our Bayesian constraints are not strong enough to reveal any dependence of the planet frequency on stellar host mass. Studies of transition disks have suggested that about 20% of stars are undergoing planet formation; our non-detections at large separations show that planets with orbital separation > 40 AU and planet masses > 3 MJup do not carve the central holes in these disks.
Gas in Dusty Debris Disks  [PDF]
Rene' Liseau
Physics , 2003,
Abstract: The presence of gas in dusty debris disks around main-sequence stars is reviewed. We present new observational results for the most prominent representative of the class, viz. the southern naked-eye star beta Pictoris. The spatial and spectral distribution of observed atomic lines from the disk around the star is reproducable by a Keplerian rotation model to a high degree of accuracy. The expected velocity dispersion due to radiation pressure in resonance lines is not observed. Modeling the motion of different atomic species under the influence of gravity, radiation pressure and gas friction leads to the conclusion that an underlying decelerating component must be present in the disk. This braking agent is most likely hydrogen, with inferred average densities n(H) > 1e6 per cubic centimeter. This could support the observational result of Thi et al. (2001) which indicated the presence of appreciable amounts of H2 around the star beta Pic.
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