Near-Infrared AO Spectroscopy of Edge-On Protoplanetary Disks with Subaru IRCS

2005 ◽  
pp. 211-213
Author(s):  
Hiroshi Terada ◽  
Naoto Kobayashi ◽  
Alan T. Tokunaga ◽  
Naruhisa Takato ◽  
Hideki Takami ◽  
...  
Keyword(s):  
Near Infrared ◽  
Protoplanetary Disks

scholarly journals Searching for H2 emission from protoplanetary disks using near- and mid-infrared high-resolution spectroscopy

2007 ◽  
Vol 3 (S249) ◽  
pp. 359-368
Author(s):  
A. Carmona ◽  
M. E. van den Ancker ◽  
Th. Henning ◽  
Ya. Pavlyuchenkov ◽  
C. P. Dullemond ◽  
...  
Keyword(s):  
Surface Layer ◽  
High Resolution ◽  
Near Infrared ◽  
Protoplanetary Disks ◽  
High Resolution Spectroscopy ◽  
Disk Model ◽  
Mid Infrared ◽  
T Tauri ◽  
Hα Emission ◽  
Ir Emission

AbstractThe mass and dynamics of protoplanetary disks are dominated by molecular hydrogen (H2). However, observationally very little is known about the H2. In this paper, we discuss two projects aimed to constrain the properties of H2 in the disk's planet forming region (R<50AU). First, we present a sensitive survey for pure-rotational H2 emission at 12.278 and 17.035 μm in a sample of nearby Herbig Ae/Be and T Tauri stars using VISIR, ESO's VLT high-resolution mid-infrared spectrograph. Second, we report on a search for H2 ro-vibrational emission at 2.1228, 2.2233 and 2.2477 μm in the classical T Tauri star LkHα 264 and the debris disk 49 Cet employing CRIRES, ESO's VLT high-resolution near-infrared spectrograph.VISIR project: none of the sources show H2 mid-IR emission. The observed disks contain less than a few tenths of MJupiter of optically thin H2 at 150 K, and less than a few MEarth at T>300 K. % and higher T. Our non-detections are consistent with the low flux levels expected from the small amount of H2 gas in the surface layer of a Chiang and Goldreich (1997) Herbig Ae two-layer disk model. In our sources the H2 and dust in the surface layer have not significantly departed from thermal coupling (Tgas/Tdust<2) and the gas-to-dust ratio in the surface layer is very likely <1000.CRIRES project: The H2 lines at 2.1218 μm and 2.2233 μm are detected in LkHα 264. An upper limit on the 2.2477 μm H2 line flux in LkHα 264 is derived. 49 Cet does not exhibit H2 emission in any of observed lines. There are a few MMoon of optically thin hot H2 in the inner disk (∼0.1 AU) of LkHα 264, and less than a tenth of a MMoon of hot H2 in the inner disk of 49 Cet. The shape of the 1–0 S(0) line indicates that LkHα disk is close to face-on (i<35o). The measured 1–0 S(0)/1–0 S(1) and 2–1 S(1)/1–0 S(1) line ratios in LkHα 264 indicate that the H2 is thermally excited at T<1500 K. The lack of H2 emission in the NIR spectra of 49 Cet and the absence of Hα emission suggest that the gas in the inner disk of 49 Cet has dissipated.

scholarly journals Carbon depletion observed inside T Tauri inner rims

2019 ◽  
Vol 632 ◽  
pp. A32 ◽  
Author(s):  
M. K. McClure
Keyword(s):  
Carbon Content ◽  
Near Infrared ◽  
Protoplanetary Disks ◽  
Far Infrared ◽  
T Tauri Stars ◽  
Outer Disk ◽  
Carbon Abundance ◽  
T Tauri ◽  
Medium Resolution ◽  
Complete Set

Context. The carbon content of protoplanetary disks is an important parameter to characterize planets formed at different disk radii. There is some evidence from far-infrared and submillimeter observations that gas in the outer disk is depleted in carbon, with a corresponding enhancement of carbon-rich ices at the disk midplane. Observations of the carbon content inside of the inner sublimation rim could confirm how much carbon remains locked in kilometer size bodies in the disk. Aims. I aim to determine the density, temperature, and carbon abundance inside the disk dust sublimation rim in a set of T Tauri stars with full protoplanetary disks. Methods. Using medium-resolution, near-infrared (0.8–2.5 μm) spectra and the new Gaia DR2 distances, I self-consistently determine the stellar, extinction, veiling, and accretion properties of the 26 stars in my sample. From these values, and non-accreting T Tauri spectral templates, I extract the inner disk excess of the target stars from their observed spectra. Then I identify a series of C0 recombination lines in 18 of these disks and use the CHIANTI atomic line database with an optically thin slab model to constrain the average ne, Te, and nc for these lines in the five disks with a complete set of lines. By comparing these values with other slab models of the inner disk using the Cloudy photoionization code, I also constrain nH and the carbon abundance, XC, and hence the amount of carbon “missing” from the slab. For one disk, DR Tau, I use relative abundances for the accretion stream from the literature to also determine XSi and XN. Results. The inner disks modeled here are extremely dense (nH ~ 1016 cm−3), warm (Te ~ 4500 K), and moderately ionized (log Xe ~ 3.3). Three of the five modeled disks show robust carbon depletion up to a factor of 42 relative to the solar value. I discuss multiple ways in which the “missing” carbon could be locked out of the accreting gas. Given the high-density inner disk gas, evidence for radial drift, and lack of obvious gaps in these three systems, their carbon depletion is most consistent with the “missing” carbon being sequestered in kilometer size bodies. For DR Tau, nitrogen and silicon are also depleted by factors of 45 and 4, respectively, suggesting that the kilometer size bodies into which the grains are locked were formed beyond the N2 snowline. I explore briefly what improvements in the models and observations are needed to better address this topic in the future.

scholarly journals The massive star-forming region Cygnus OB2

2009 ◽  
Vol 5 (S266) ◽  
pp. 551-554
Author(s):  
N. J. Wright ◽  
J. J. Drake
Keyword(s):  
Massive Star ◽  
Near Infrared ◽  
Protoplanetary Disks ◽  
Mass Function ◽  
Initial Mass Function ◽  
Point Sources ◽  
Older Population ◽  
X Ray ◽  
Ob Stars ◽  
Star Forming

AbstractWe present results from a catalogue of 1696 X-ray point sources detected in the massive star-forming region Cygnus OB2, the majority of which have optical or near-infrared associations. We derive ages of 3.5 and 5.25 Myr for the stellar populations in our two fields, in agreement with recent studies that suggest that the central 1–3 Myr-old OB association is surrounded and contaminated by an older population with an age of 5–10 Myr. The fraction of sources with protoplanetary disks, as traced by K-band excesses, is unusually low. Although this has previously been interpreted as due to the influence of the large number of OB stars in Cyg OB2, contamination from an older population of stars in the region could also be responsible. An initial mass function is derived and found to have a slope of Γ = −1.27, in agreement with the canonical value. Finally, we introduce the recently approved Chandra Cygnus OB2 Legacy Survey that will image a 1 square degree area of the Cygnus OB2 association to a depth of 120~ks, likely detecting ~ 10 000 stellar X-ray sources.

scholarly journals Direct imaging of bridged twin protoplanetary disks in a young multiple star

2010 ◽  
Vol 6 (S276) ◽  
pp. 506-507
Author(s):  
Satoshi Mayama ◽  
Motohide Tamura ◽  
Tomoyuki Hanawa ◽  
Tomoaki Matsumoto ◽  
Miki Ishii ◽  
...  
Keyword(s):  
Shock Wave ◽  
Numerical Simulations ◽  
Gas Flow ◽  
Near Infrared ◽  
Protoplanetary Disks ◽  
Infrared Emission ◽  
Direct Imaging ◽  
Multiple Star ◽  
Fresh Material ◽  
Spiral Arm

AbstractStudies of the structure and evolution of protoplanetary disks are important for understanding star and planet formation. Here, we present the direct image of an interacting binary protoplanetary system. Both circumprimary and circumsecondary disks are resolved in the near-infrared. There is a bridge of infrared emission connecting the two disks and a long spiral arm extending from the circumprimary disk. Numerical simulations show that the bridge corresponds to gas flow and a shock wave caused by the collision of gas rotating around the primary and secondary stars. Fresh material streams along the spiral arm, consistent with the theoretical scenarios where gas is replenished from a circummultiple reservoir.

scholarly journals Simultaneous Visible and Near-Infrared Variability of Classical T Tauri Stars

2013 ◽  
Vol 8 (S299) ◽  
pp. 149-150
Author(s):  
Yukako Aimi ◽  
Misato Fukagawa ◽  
Tomonori Yasuda ◽  
Takuya Yamashita ◽  
Kouji Kawabata ◽  
...  
Keyword(s):  
Hot Spots ◽  
Structural Changes ◽  
Near Infrared ◽  
Protoplanetary Disks ◽  
Circumstellar Matter ◽  
T Tauri Stars ◽  
The Other ◽  
Stellar Systems ◽  
Be Stars ◽  
T Tauri

AbstractTemporal structural changes of protoplanetary disks surrounding T Tauri stars (TTSs) can cause magnitude variations of TTSs. On the other hand, variability is also expected due to cool spots and/or hot spots on the surface of the star, thus it is important to distinguish the causes of the observed variability. Our sample consists of 23 TTSs (22 classical T Tauri stars, 1 weak-lined T Tauri star) and 4 Herbig Ae/Be stars. The observations were performed over a period of about 3 months in the V, J, and KS band, simultaneously. We detected variability for all stars in the three bands (>0.05 mag in V, >0.09 mag in J, >0.09 mag in KS). Color-magnitude relations obtained between V, J, and KS bands suggest that stellar spots are not the only cause of variability for most of our targets. In addition, the data implies that six stellar systems contain larger grains than in the interstellar medium if the variability is only caused by extinction due to circumstellar matter.

scholarly journals SURFACE GEOMETRY OF PROTOPLANETARY DISKS INFERRED FROM NEAR-INFRARED IMAGING POLARIMETRY

2014 ◽  
Vol 795 (1) ◽  
pp. 71 ◽  
Author(s):  
Michihiro Takami ◽  
Yasuhiro Hasegawa ◽  
Takayuki Muto ◽  
Pin-Gao Gu ◽  
Ruobing Dong ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Protoplanetary Disks ◽  
Surface Geometry ◽  
Near Infrared Imaging ◽  
Imaging Polarimetry

scholarly journals Surface waves in protoplanetary disks induced by outbursts: Concentric rings in scattered light

2018 ◽  
Vol 617 ◽  
pp. L7
Author(s):  
A. D. Schneider ◽  
C. P. Dullemond ◽  
B. Bitsch
Keyword(s):  
Radiative Transfer ◽  
Surface Waves ◽  
Vertical Structure ◽  
Near Infrared ◽  
Scattered Light ◽  
Protoplanetary Disks ◽  
Protoplanetary Disk ◽  
Diffusion Method ◽  
Disk Structure ◽  
Infrared Wavelengths

Context. Vertically hydrostatic protoplanetary disk models are based on the assumption that the main heating source, stellar irradiation, does not vary much with time. However, it is known that accreting young stars are variable sources of radiation. This is particularly evident for outbursting sources such as EX Lupi and FU Orionis stars. Aims. We investigate how such outbursts affect the vertical structure of the outer regions of the protoplanetary disk, in particular their appearance in scattered light at optical and near-infrared wavelengths. Methods. We employ the 3D FARGOCA radiation-hydrodynamics code, in polar coordinates, to compute the time-dependent behavior of the axisymmetric disk structure. The temperature is computed self-consistently and time-dependently from the irradiation flux using a two-stage radiative transfer method: first the direct illumination is computed; then the diffuse radiation is treated with the flux-limited diffusion method. The outbursting inner disk region is not included explicitly. Instead, its luminosity is added to the stellar luminosity and is thus included in the irradiation of the outer disk regions. For time snapshots of interest we insert the density structure into the RADMC-3D radiative transfer code and compute the appearance of the disk at optical/near-infrared wavelengths, where we observe stellar light that is scattered off the surface of the disk. Results. We find that, depending on the amplitude of the outbursts, the vertical structure of the disk can become highly dynamic, featuring circular surface waves of considerable amplitude. These “hills” and “valleys” on the disk’s surface show up in the scattered light images as bright and dark concentric rings. Initially these rings are small and act as standing waves, but they subsequently lead to outward propagating waves, like the waves produced by a stone thrown into a pond. These waves continue long after the actual outburst has died out. Conclusions. Single, periodic, or quasiperiodic outbursts of the innermost regions of protoplanetary disks will necessarily lead to wavy structures on the surface of these disks at all radii. We propose that some of the multi-ringed structures seen in optical/infrared images of several protoplanetary disks may have their origin in outbursts that occurred decades or centuries ago. However, the multiple rings seen at (sub-)millimeter wavelengths in HL Tau and several other disks are not expected to be related to such waves.

scholarly journals The Inner Environment of Protoplanetary Disks With Near-infrared Spectro-interferometry

2009 ◽  
Author(s):  
E. Tatulli ◽  
Tomonori Usuda ◽  
Motohide Tamura ◽  
Miki Ishii
Keyword(s):  
Near Infrared ◽  
Protoplanetary Disks

scholarly journals The GRAVITY Young Stellar Object survey

2019 ◽  
Vol 632 ◽  
pp. A53 ◽  
Author(s):  
◽  
K. Perraut ◽  
L. Labadie ◽  
B. Lazareff ◽  
L. Klarmann ◽  
...  
Keyword(s):  
Near Infrared ◽  
Planet Formation ◽  
Protoplanetary Disks ◽  
Circumstellar Disks ◽  
Mass Range ◽  
Size Ratio ◽  
Mass Star ◽  
Be Stars ◽  
Band Size ◽  
Group I

Context. The formation and the evolution of protoplanetary disks are important stages in the lifetime of stars. Terrestrial planets form or migrate within the innermost regions of these protoplanetary disks and so, the processes of disk evolution and planet formation are intrinsically linked. Studies of the dust distribution, composition, and evolution of these regions are crucial to understanding planet formation. Aims. We built a homogeneous observational dataset of Herbig Ae/Be disks with the aim of spatially resolving the sub au-scale region to gain a statistical understanding of their morphological and compositional properties, in addition to looking for correlations with stellar parameters, such as luminosity, mass, and age. Methods. We observed 27 Herbig Ae/Be stars with the GRAVITY instrument installed at the combined focus of the Very Large Telescope Interferometer (VLTI) and operating in the near-infrared K-band, focused on the K-band thermal continuum, which corresponds to stellar flux reprocessed by the dust grains. Our sample covers a large range of effective temperatures, luminosities, masses, and ages for the intermediate-mass star population. The circumstellar disks in our sample also cover a range of various properties in terms of reprocessed flux, flared or flat morphology, and gaps. We developed semi-physical geometrical models to fit our interferometric data. Results. Our best-fit models correspond to smooth and wide rings that support previous findings in the H-band, implying that wedge-shaped rims at the dust sublimation edge are favored. The measured closure phases are generally non-null with a median value of ~10°, indicating spatial asymmetries of the intensity distributions. Multi-size grain populations could explain the closure phase ranges below 20–25° but other scenarios should be invoked to explain the largest ones. Our measurements extend the Radius-Luminosity relation to ~104 L⊙ luminosity values and confirm the significant spread around the mean relation observed by PIONIER in the H-band. Gapped sources exhibit a large N-to-K band size ratio and large values of this ratio are only observed for the members of our sample that would be older than 1 Ma, less massive, and with lower luminosity. In the mass range of 2 M⊙, we do observe a correlation in the increase of the relative age with the transition from group II to group I, and an increase of the N-to-K size ratio. However, the size of the current sample does not yet permit us to invoke a clear, universal evolution mechanism across the Herbig Ae/Be mass range. The measured locations of the K-band emission in our sample suggest that these disks might be structured by forming young planets, rather than by depletion due to EUV, FUV, and X-ray photo-evaporation.

scholarly journals Evolution of protoplanetary disks from their taxonomy in scattered light: spirals, rings, cavities, and shadows

2018 ◽  
Vol 620 ◽  
pp. A94 ◽  
Author(s):  
A. Garufi ◽  
M. Benisty ◽  
P. Pinilla ◽  
M. Tazzari ◽  
C. Dominik ◽  
...  
Keyword(s):  
Main Sequence ◽  
Near Infrared ◽  
Scattered Light ◽  
Selection Effect ◽  
Protoplanetary Disks ◽  
Young Stars ◽  
Outer Disk ◽  
Disk Mass ◽  
Dust Mass ◽  
Taxonomical Study

Context. Dozens of protoplanetary disks have been imaged in scattered light during the last decade. Aims. The variety of brightness, extension, and morphology from this census motivates a taxonomical study of protoplanetary disks in polarimetric light to constrain their evolution and establish the current framework of this type of observation. Methods. We classified 58 disks with available polarimetric observations into six major categories (Ring, Spiral, Giant, Rim, Faint, and Small disks) based on their appearance in scattered light. We re-calculated the stellar and disk properties from the newly available Gaia DR2 and related these properties with the disk categories. Results. More than half of our sample shows disk substructures. For the remaining sources, the absence of detected features is due to their faintness, their small size, or the disk geometry. Faint disks are typically found around young stars and typically host no cavity. There is a possible dichotomy in the near-infrared (NIR) excess of sources with spiral-disks (high) and ring-disks (low). Like spirals, shadows are associated with a high NIR excess. If we account for the pre-main sequence evolutionary timescale of stars with different mass, spiral arms are likely associated with old disks. We also found a loose, shallow declining trend for the disk dust mass with time. Conclusions. Protoplanetary disks may form substructures like rings very early in their evolution but their detectability in scattered light is limited to relatively old sources ( ≳5 Myr) where the recurrently detected disk cavities cause the outer disk to be illuminate. The shallow decrease of disk mass with time might be due to a selection effect, where disks observed thus far in scattered light are typically massive, bright transition disks with longer lifetimes than most disks. Our study points toward spirals and shadows being generated by planets of a fraction of a Jupiter mass to a few Jupiter masses in size that leave their (observed) imprint on both the inner disk near the star and the outer disk cavity.

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