We report the discovery of a wide (~400 AU projected separation), common proper motion companion to the nearby M dwarf LHS 2803 (PSO J207.0300-13.7422). This object was discovered during our census ...of the local T dwarf population using Pan-STARRS1 and Two Micron All Sky Survey data. Using the Infrared Telescope Facility/SpeX near-infrared spectroscopy, we classify the secondary to be spectral type T5.5. University of Hawaii 2.2 m/SuperNova Integral Field Spectrograph optical spectroscopy indicates that the primary has a spectral type of M4.5, with approximately solar metallicity and no measurable Halpha emission. We use this lack of activity to set a lower age limit for the system of 3.5 Gyr. Using a comparison with chance alignments of brown dwarfs and nearby stars, we conclude that the two objects are unlikely to be a chance association. The primary's photometric distance of 21 pc and its proper motion implies thin disk kinematics. Based on these kinematics and its metallicity, we set an upper age limit for the system of 10 Gyr. Evolutionary model calculations suggest that the secondary has a mass of 72+ or - super(4) sub(7) M sub(Jup), temperature of 1120 + or - 80 K, and log g = 5.4 + or - 0.1 dex. Model atmosphere fitting to the near-IR spectrum gives similar physical parameters of 1100 K and log g = 5.0.
We report K'-band imaging observations of the reflection nebula associated with Cepheus A East covering the time interval from 1990 to 2004. Over this time the reflection nebula shows variations of ...flux distribution, which we interpret as the effect of inhomogeneous and varying extinction in the light path from the illuminating source HW2 to the reflection nebula. The obscuring material is located within typical distances of 10 AU from the illuminating source.
We present high-contrast H-band polarized intensity (PI) images of the transitional disk around the young solar like star GM Aur. The near-infrared direct imaging of the disk was derived by ...polarimetric differential imaging using the Subaru 8.2 m Telescope and HiCIAO. An angular resolution and an inner working angle of 0 07 and radius approximately 0 05, respectively, were obtained. We clearly resolved a large inner cavity, with a measured radius of 18+/ 2 au, which is smaller than that of a submillimeter interferometric image (28 au). This discrepancy in the cavity radii at near-infrared and submillimeter wavelengths may be caused by a 34M(sub Jup) planet about 20 au away from the star, near the edge of the cavity. The presence of a near-infrared inner cavity is a strong constraint on hypotheses for inner cavity formation in a transitional disk. A dust filtration mechanism has been proposed to explain the large cavity in the submillimeter image, but our results suggest that this mechanism must be combined with an additional process. We found that the PI slope of the outer disk is significantly different from the intensity slope obtained from HSTNICMOS, and this difference may indicate the grain growth process in the disk.
ABSTRACT We present a new analysis of multi-epoch, H-band, scattered light images of the AB Aur system. We use a Monte Carlo radiative transfer code to simultaneously model the system's spectral ...energy distribution (SED) and H-band polarized intensity (PI) imagery. We find that a disk-dominated model, as opposed to one that is envelope-dominated, can plausibly reproduce AB Aur's SED and near-IR imagery. This is consistent with previous modeling attempts presented in the literature and supports the idea that at least a subset of AB Aur's spirals originate within the disk. In light of this, we also analyzed the movement of spiral structures in multi-epoch H-band total light and PI imagery of the disk. We detect no significant rotation or change in spatial location of the spiral structures in these data, which span a 5.8-year baseline. If such structures are caused by disk-planet interactions, the lack of observed rotation constrains the location of the orbit of planetary perturbers to be >47 au.
We present new high-resolution (~0."09) H-band imaging observations of the circumstellar disk around the T Tauri star SU Aur. Our observations with Subaru-HiCIAO have revealed the presence of ...scattered light as close as 0."15 (~20 AU) to the star. Within our image, we identify bright emission associated with a disk with a minimum radius of ~90 AU, an inclination of ~35degrees from the plane of the sky, and an approximate PA of 15degrees for the major axis. We find a brightness asymmetry between the northern and southern sides of the disk due to a non-axisymmetric disk structure. We also identify a pair of asymmetric tail structures extending east and west from the disk. The western tail extends at least 2."5 (350 AU) from the star, and is probably associated with a reflection nebula previously observed at optical and near-IR wavelengths. The eastern tail extends at least 1" (140 AU) at the present signal-to-noise. These tails are likely due to an encounter with an unseen brown dwarf, but our results do not exclude the explanation that these tails are outflow cavities or jets.
A Common Proper Motion Stellar Companion to HAT-P-7 Narita, Norio; Takahashi, Yasuhiro H; Kuzuhara, Masayuki ...
Publications of the Astronomical Society of Japan,
12/2012, Letnik:
64, Številka:
6
Journal Article
Recenzirano
Odprti dostop
We report that HAT-P-7 has a common proper motion stellar companion. The companion is located at
$ \sim$
3
$ .\!\!\!''$
9 to the east and estimated to be an M5.5V dwarf based on its colors. We also ...confirm the presence of a third companion, which was first reported by Winn et al. (2009, ApJ, 703, L99), based on long-term radial velocity measurements. We revisit the migration mechanism of HAT-P-7b given to the presence of those companions, and propose the sequential Kozai migration as a likely scenario in this system. This scenario may explain the reason for an outlier in the discussion of the spin-orbit alignment timescale for HAT-P-7b by Albrecht et al. (2012, ApJ, 757, 18).
The NGC 1333 region was observed in the H sub(2) 1-0 S(1) line. The H sub(2) images cover a 5' x 7' region around IRAS 4. Numerous H sub(2) emission features were detected. The northeast-southwest ...bipolar outflow driven by IRAS 4A was studied by combining the H sub(2) images with SiO maps published previously. The SiO-H sub(2) outflows are continuous on the southwestern side but show a gap on the northeastern side. The southwestern outflow lobe curves smoothly, and the position angle increases with the distance from the driving source. The base and the outer tip of the northeastern outflow lobe are located at positions opposite to the corresponding parts of the southwestern lobe. This point symmetry suggests that the outflow axis may be drifting or precessing clockwise in the plane of the sky and that the cause of the axis drift may be intrinsic to the outflow engine. The axis drift model is supported by the asymmetric lateral intensity profile of the SiO outflow. The axis drift rate is 60.011 yr super(-1). The middle part of the northeastern outflow does not exactly follow the point symmetry because of the superposition of two different kinds of directional variability: the axis drift of the driving source and the deflection by a dense core. The axis drift model provides a good explanation for the large deflection angle of the northeastern outflow. Other H sub(2) emission features around the IRAS 4 region are discussed briefly. Some of them are newly found outflows, and some are associated with outflows already known before.
ABSTRACT We present the first spatially resolved polarized scattered light H-band detection of the DoAr 28 transitional disk. Our two epochs of imagery detect the scattered light disk from our ...effective inner working angle of 0 10 (13 AU) out to 0 50 (65 AU). This inner working angle is interior to the location of the system's gap inferred by previous studies using spectral energy distribution modeling (15 AU). We detected a candidate point source companion 1 08 northwest of the system; however, our second epoch of imagery strongly suggests that this object is a background star. We constructed a grid of Monte Carlo Radiative Transfer models of the system, and our best fit models utilize a modestly inclined (50°), 0.01 disk that has a partially depleted inner gap from the dust sublimation radius out to ∼8 AU. Subtracting this best fit, axi-symmetric model from our polarized intensity data reveals evidence for two small asymmetries in the disk, which could be attributable to a variety of mechanisms.
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