131 research outputs found
SUBARU Near-Infrared Multi-Color Images of Class II Young Stellar Object, RNO91
We conducted sub-arcsecond near-infrared imaging observations of RNO91 with
CIAO mounted on the SUBARU 8.2 m telescope. We present our JHK band data along
with optical images, which when considered together reveal a complex
circumstellar structure. We examined the colors of associated nebula and
compared the geometry of the outflow/disk system suggested by our data with
that already proposed on the basis of previous studies. Our K-band image shows
bright circumstellar nebulosity detected within 2"(300AU) around the central
source while it is less conspicuous at shorter wavelengths such as J and
optical. P.A. and size of this red color nebulosity in our H-K color image
agree with those of the previously detected polarization disk. These data
agreement indicate that this bright circumstellar nebulosity region which
follows the reddening law might be attributed to a disk-like structure. At J
and optical wavelengths, several blue knot-like structures are detected around
and beyond the bright circumstellar nebulosity. We suggest that these knotty
reflection nebulae may represent disintegrating fragments of an infalling
envelope. The three-color composite image has an appearance of arc-shaped
nebulosity extending to the north and to the east through the central source.
On the other end of this arc-shaped structure, the nebula appears to become
more extended (2."3 long) to the southwest. We interpret these structures as
roots of bipolar cavities opening to the northeast and southwest. The complex
distribution of reflection nebulosity seen around RNO91 appears to confirm the
interpretation of this source as an object dispersing its molecular envelope
while transitioning from protostar to T Tauri star.Comment: 18 pages, 6 figures, Accepted by Publications of the Astronomical
Society of Japa
Chimpanzee face recognition from videos in the wild using deep learning
Video recording is now ubiquitous in the study of animal behavior, but its analysis on a large scale is prohibited by the time and resources needed to manually process large volumes of data. We present a deep convolutional neural network (CNN) approach that provides a fully automated pipeline for face detection, tracking, and recognition of wild chimpanzees from long-term video records. In a 14-year dataset yielding 10 million face images from 23 individuals over 50 hours of footage, we obtained an overall accuracy of 92.5% for identity recognition and 96.2% for sex recognition. Using the identified faces, we generated co-occurrence matrices to trace changes in the social network structure of an aging population. The tools we developed enable easy processing and annotation of video datasets, including those from other species. Such automated analysis unveils the future potential of large-scale longitudinal video archives to address fundamental questions in behavior and conservation.Agência financiadora Número do subsídio
Engineering & Physical Sciences Research Council (EPSRC)
EP/M013774/1
Cooperative Research Program of Primate Research Institute, Kyoto University
Google
Clarendon Fund
Boise Trust Fund
Wolfson College, University of Oxford
Leverhulme Trust
PLP-2016-114
Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)
Japan Society for the Promotion of Science
16H06283
Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)
Japan Society for the Promotion of Science
LGP-U04info:eu-repo/semantics/publishedVersio
Near-Infrared Coronagraphic Observations of the T Tauri Binary System UY Aur
We present a near-infrared image of UY Aur, a 0.9" separated binary system,
using the Coronagraphic Imager with Adaptive Optics on the Subaru Telescope.
Thanks to adaptive optics, the spatial resolution of our image was ~0.1" in the
full width at half maximum of the point spread function, the highest achieved.
By comparison with previous measurements, we estimated that the orbital period
is ~1640 yrs and the total mass of the binary is ~1.73 solar mass. The observed
H-band magnitude of the secondary varies by as much as 1.3 mag within a decade,
while that of the primary is rather stable. This inconstancy may arise from
photospheric variability caused by an uneven accretion rate or from the
rotation of the secondary. We detected a half-ring shaped circumbinary disk
around the binary with a bright southwest part but a barely detectable
northeast portion. The brightness ratio is ~57. Its inner radius and
inclination are about 520 AU and 42, respectively. The disk is not uniform but
has remarkable features, including a clumpy structure along the disk,
circumstellar material inside the inner cavity, and an extended armlike
structure. The circumstellar material inside the cavity probably corresponds to
a clump or material accreting from the disk onto the binary. The armlike
structure is a part of the disk, created by the accretion from the outer region
of the disk or encounters with other stellar systems.Comment: 16 pages, 6 figures; accepted for publication in A
Near-Infrared Imaging Survey of Faint Companions around Young Dwarfs in the Pleiades Cluster
We conducted a near-infrared imaging survey of 11 young dwarfs in the
Pleiades cluster using the Subaru Telescope and the near-infrared coronagraph
imager. We found 10 faint point sources, with magnitudes as faint as 20 mag in
the K-band, around 7 dwarfs. Comparison with Spitzer archive images revealed
that a pair of the faint sources around V 1171 Tau are very red in the infrared
wavelengths, indicative of very low-mass young stellar objects. However, the
results of our follow-up proper motion measurements implied that the central
star and the faint sources do not share common proper motions, suggesting that
they are not physically associated.Comment: 13 pages. Accepted for publication in Research in Astronomy and
Astrophysic
H band Image of a Planetary Companion around HR 8799 in 2002
The discovery of three planetary companions around HR 8799 (Marois et al.
2008) marked a significant epoch in direct imaging of extrasolar planets. Given
the importance of this system, we re-analyzed H band images of HR 8799 obtained
with the Subaru 36-elements adaptive optics (AO) in July 2002. The low-order AO
imaging combined with the classical PSF-subtraction methods even revealed the
extrasolar planet, HR 8799b. Our observations in 2002 confirmed that it has
been orbiting HR 8799 in a counter-clockwise direction. The flux of HR 8799b
was consistent with those in the later epochs within the uncertainty of 0.25
mag, further supporting the planetary mass estimate by Marois et al. (2008).Comment: 14 pages, 4 figures, accepted for publication in ApJ Lette
Automated face recognition using deep neural networks produces robust primate social networks and sociality measures
Longitudinal video archives of behaviour are crucial for examining how sociality shifts over the lifespan in wild animals. New approaches adopting computer vision technology hold serious potential to capture interactions and associations between individuals in video at large scale; however, such approaches need a priori validation, as methods of sampling and defining edges for social networks can substantially impact results.Here, we apply a deep learning face recognition model to generate association networks of wild chimpanzees using 17 years of a video archive from Bossou, Guinea. Using 7 million detections from 100 h of video footage, we examined how varying the size of fixed temporal windows (i.e. aggregation rates) for defining edges impact individual-level gregariousness scores.The highest and lowest aggregation rates produced divergent values, indicating that different rates of aggregation capture different association patterns. To avoid any potential bias from false positives and negatives from automated detection, an intermediate aggregation rate should be used to reduce error across multiple variables. Individual-level network-derived traits were highly repeatable, indicating strong inter-individual variation in association patterns across years and highlighting the reliability of the method to capture consistent individual-level patterns of sociality over time. We found no reliable effects of age and sex on social behaviour and despite a significant drop in population size over the study period, individual estimates of gregariousness remained stable over time.We believe that our automated framework will be of broad utility to ethology and conservation, enabling the investigation of animal social behaviour from video footage at large scale, low cost and high reproducibility. We explore the implications of our findings for understanding variation in sociality patterns in wild ape populations. Furthermore, we examine the trade-offs involved in using face recognition technology to generate social networks and sociality measures. Finally, we outline the steps for the broader deployment of this technology for analysis of large-scale datasets in ecology and evolution.info:eu-repo/semantics/publishedVersio
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