| 1. |
- Granlund, Åsa, et al.
(författare)
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A pattern-supported approach to the user interface design process
- 2001
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Ingår i: Proceedings of HCI International 2001.
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Konferensbidrag (refereegranskat)abstract
- Patterns describe generic solutions to common problems in context. Originating from the world of architecture, patterns have been used mostly in object-oriented programming and data analysis. The goal of HCI patterns is to create an inventory of solutions to help designers (and usability engineers) to resolve UI development problems that are common, difficult and frequently encountered. In this paper, we present our pattern-supported approach to user interface design in the context of information visualization. Using a concrete example from the telecommunications domain, we will focus on a task/subtask pattern to illustrate how knowledge about a task and an appropriate interaction design solution can be captured and communicated.
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| 2. |
- Baron, Frédérique, et al.
(författare)
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WEIRD : Wide-orbit Exoplanet Search with InfraRed Direct Imaging
- 2018
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 156:3
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Tidskriftsartikel (refereegranskat)abstract
- We report results from the Wide-orbit Exoplanet search with InfraRed Direct imaging, or WEIRD, a survey designed to search for Jupiter-like companions on very wide orbits (1000-5000 au) around young stars (<120 Myr) that are known members of moving groups in the solar neighborhood (<70 pc). Companions that share the same age, distance, and metallicity as their host while being on large enough orbits to be studied as isolated objects make prime targets for spectroscopic observations, and they are valuable benchmark objects for exoplanet atmosphere models. The search strategy is based on deep imaging in multiple bands across the near-infrared domain For all 177 objects of our sample, z(ab)', J, [3.6], and [4.5] images were obtained with CFHT/MegaCam, GEMINI/GMOS, CFHT/WIRCam, GEMINI/Flamingos-2, and Spitzer IIRAC. Using this set of four images per target, we searched for sources with red z(ab)' and [3.6]-[4.5] colors, typically reaching good completeness down to 2 M-J(up) companions, while going down to 1 M-J(up) for some targets, at separations of 1000-5000 au. The search yielded four candidate companions with the expected colors, but they were all rejected through follow-up proper motion observations. Our results constrain the occurrence of 1-13 M(J)(u)p planetary-mass companions on orbits with a semimajor axis between 1000 and 5000 au at less than 0.03, with a 95% confidence level.
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| 3. |
- Daemgen, Sebastian, et al.
(författare)
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SUB-STELLAR COMPANIONS AND STELLAR MULTIPLICITY IN THE TAURUS STAR-FORMING REGION
- 2015
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 799:2
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Tidskriftsartikel (refereegranskat)abstract
- We present results from a large, high- spatial- resolution near- infrared imaging search for stellar and sub- stellar companions in the Taurus- Auriga star- forming region. The sample covers 64 stars with masses between those of the most massive Taurus members at 3 M-circle dot and low-mass stars at 0.2 M-circle dot. We detected 74 companion candidates, 34 of these reported for the first time. Twenty- five companions are likely physically bound, partly confirmed by follow- up observations. Four candidate companions are likely unrelated field stars. Assuming physical association with their host star, estimated companion masses are as low as 2M(Jup.) The inferred multiplicity frequency within our sensitivity limits between 10-1500 AU is 26.3(-4.9)(+ 6.6)% - 4.9%. Applying a completeness correction, 62% 14% of all Taurus stars between 0.7 and 1.4 M appear to be multiple. Higher order multiples were found in 1.8+ 4.2 - 1.5 % of the cases, in agreement with previous observations of the field. We estimate a sub- stellar companion frequency of 3.5%- 8.8% within our sensitivity limits from the discovery of two likely bound and three other tentative very low- mass companions. This frequency appears to be in agreement with what is expected from the tail of the stellar companion mass ratio distribution, suggesting that stellar and brown dwarf companions share the same dominant formation mechanism. Further, we find evidence for possible evolution of binary parameters between two identified sub- populations in Taurus with ages of 2 Myr and 20 Myr, respectively.
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| 4. |
- Janson, Markus, et al.
(författare)
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A MULTIPLICITY CENSUS OF INTERMEDIATE-MASS STARS IN SCORPIUS-CENTAURUS
- 2013
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 773:2, s. 170-
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Tidskriftsartikel (refereegranskat)abstract
- Stellar multiplicity properties have been studied for the lowest and the highest stellar masses, but intermediate-mass stars from F-type to late A-type have received relatively little attention. Here, we report on a Gemini/NICI snapshot imaging survey of 138 such stars in the young Scorpius-Centaurus (Sco-Cen) region, for the purpose of studying multiplicity with sensitivity down to planetary masses at wide separations. In addition to two brown dwarfs and a companion straddling the hydrogen-burning limit which we reported previously, here we present 26 new stellar companions and determine a multiplicity fraction within 0 ''.1-5 ''.0 of 21% +/- 4%. Depending on the adopted semimajor axis distribution, our results imply a total multiplicity in the range of similar to 60%-80%, which further supports the known trend of a smooth continuous increase in the multiplicity fraction as a function of primary stellar mass. A surprising feature in the sample is a distinct lack of nearly equal-mass binaries, for which we discuss possible reasons. The survey yielded no additional companions below or near the deuterium-burning limit, implying that their frequency at >200 AU separations is not quite as high as might be inferred from previous detections of such objects within the Sco-Cen region.
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| 5. |
- Janson, Markus, et al.
(författare)
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High-contrast imaging with Spitzer : deep observations of Vega, Fomalhaut, and is an element of Eridani
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 574
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Tidskriftsartikel (refereegranskat)abstract
- Stars with debris disks are intriguing targets for direct imaging exoplanet searches, owing both to previous detections of wide planets in debris disk systems. and to commonly existing morphological features in the disks themselves that may be indicative of a planetary influence. Here we present observations of three of the most nearby young stars, which are also known to host massive debris disks: Vega. Fomalhaut, and c Fri. The Spitzer Space Telescope is used at a range of orientation angles for each star to supply a deep conumst through angular differential imaging combined with high contrast algorithms. The observations provide the opportunity to probe substantially colder bound planets (120-330 I() than is possible with any other technique or instrument. For Vega, sonic apparently very red candidate point sources detected in the 4.5 pm image remain to be tested for common proper motion. The images are sensitive to similar to 2 M-JUP companions at 150 AU in this system. The observations presented here represent the first search for planets around Vega using Spitzer. The upper 4.5 mu m flux limit on Fomalhaut b could be further constrained relative to previous data ln the case of is an element of Ed, planets below both the effective temperature and the mass of Jupiter could be probed from 80 AU and outward, although no such planets were found. The data sensitively probe the regions around the edges of the debris rings in the systems where planets can be expected to reside. These observations validate previous results showing that more than an order of magnitude improvement in performance in the contrast -limited regime can be acquired with respect to conventional methods by applying sophisticated high contrast techniques to space based telescopes, thanks to the high degree of PSF stability provided in this environment.
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| 6. |
- Janson, Markus, et al.
(författare)
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NEW BROWN DWARF COMPANIONS TO YOUNG STARS IN SCORPIUS-CENTAURUS
- 2012
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Ingår i: The Astrophysical Journal Letters. - 2041-8205. ; 758:1, s. L2-
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Tidskriftsartikel (refereegranskat)abstract
- We present the discoveries of three faint companions to young stars in the Scorpius-Centaurus region, imaged with the NICI instrument on Gemini South. We have confirmed all three companions through common proper motion tests. Follow-up spectroscopy has confirmed two of them, HIP 65423 B and HIP 65517 B, to be brown dwarfs, while the third, HIP 72099 B, is more likely a very low mass star just above the hydrogen burning limit. The detection of wide companions in the mass range of similar to 40-100 M-jup complements previous work in the same region, reporting detections of similarly wide companions with lower masses, in the range of similar to 10-30 M-jup. Such low masses near the deuterium burning limit have raised the question of whether those objects formed like planets or stars. The existence of intermediate objects as reported here could represent a bridge between lower-mass companions and stellar companions, but in any case demonstrate that mass alone may not provide a clear-cut distinction for the formation of low-mass companions to stars.
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| 7. |
- Lafreniere, David, et al.
(författare)
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A Multiplicity Census of Young Stars in Chamaeleon I
- 2008
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 683:2, s. 844-861
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of a multiplicity survey of 126 stars spanning ~0.1-3 Msolar in the ~2 Myr old Chamaeleon I star-forming region, based on adaptive optics imaging with the ESO Very Large Telescope. Our observations have revealed 30 binaries and six triples, of which 19 and four, respectively, are new discoveries. The overall multiplicity fraction we find for Cha I (~30%) is similar to those reported for other dispersed young associations, but significantly higher than seen in denser clusters and the field, for comparable samples. Both the frequency and the maximum separation of Cha I binaries decline with decreasing mass, while the mass ratios approach unity; conversely, tighter pairs are more likely to be equal mass. We confirm that brown dwarf companions to stars are rare, even at young ages at wide separations. Based on follow-up spectroscopy of two low-mass substellar companion candidates, we conclude that both are likely background stars. The overall multiplicity fraction in Cha I is in rough agreement with numerical simulations of cloud collapse and fragmentation, but its observed mass dependence is less steep than predicted. The paucity of higher order multiples, in particular, provides a stringent constraint on the simulations, and seems to indicate a low level of turbulence in the prestellar cores in Cha I.
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| 8. |
- Lafreniere, David, et al.
(författare)
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AN ADAPTIVE OPTICS MULTIPLICITY CENSUS OF YOUNG STARS IN UPPER SCORPIUS
- 2014
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 785:1, s. 47-
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of amultiplicity survey of 91 stars spanning masses of similar to 0.2-10M(circle dot) in the Upper Scorpius star-forming region, based on adaptive optics imaging with the Gemini North telescope. Our observations identified 29 binaries, 5 triples, and no higher order multiples. The corresponding raw multiplicity frequency is 0.37 +/- 0.05. In the regime where our observations are complete-companion separations of 0 ''.1-5 '' (similar to 15-800 AU) with magnitude limits ranging from K < 9.3 at 0 ''.1 to K < 15.8 at 5 '' -the multiplicity frequency is 0.27(-0.04.)(+ 0.05) For similar separations, the multiplicity frequency in Upper Scorpius is comparable to that in other dispersed star-forming regions, but is a factor of two to three higher than in denser star-forming regions or in the field. Our sample displays a constant multiplicity frequency as a function of stellar mass. Among our sample of binaries, we find that both wider (> 100 AU) and higher-mass systems tend to have companions with lower companion-to-primary mass ratios. Three of the companions identified in our survey are unambiguously substellar and have estimated masses below 0.04M(circle dot) (two of them are new discoveries from this survey-1RXS J160929.1-210524b and HIP 78530B-although we have reported them separately in earlier papers). These three companions have projected orbital separations of 300-900 AU. Based on a statistical analysis factoring in sensitivity limits, we calculate an occurrence rate of 5-40 M-Jup companions of similar to 4.0% for orbital separations of 250-1000 AU, compared to < 1.8% at smaller separations, suggesting that such companions are more frequent on wider orbits.
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