scholarly journals HST Imaging of New Edge-on Circumstellar Disks in Nearby Star-forming Regions

2013 ◽  
Vol 8 (S299) ◽  
pp. 99-103
Author(s):  
K.R. Stapelfeldt ◽  
G. Duchêne ◽  
M. Perrin ◽  
S. Wolff ◽  
J.E. Krist ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Scattered Light ◽  
Spectral Energy Distribution ◽  
Circumstellar Disks ◽  
Central Star ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Ancillary Data ◽  
Nearby Star ◽  
Space Telescope

AbstractEdge-on, optically thick circumstellar disks have been previously imaged at subarcsecond resolution around about a dozen nearby young stellar objects. In these systems the central star is occulted from direct view, bright star image artifacts are absent, and the disk reflected light is clearly seen. Comparison of Hubble Space Telescope (HST) edge-on disk images with scattered light models has allowed key disk structural parameters and dust grain properties to be determined. Edge-on disks have been systematically undercounted to date: while 10% of young stars should statistically be occulted by their disk, the observed frequency is much less. Thus there is a significant potential for discovering and imaging new examples. Spitzer Space Telescope legacy science programs have provided the first good spectral energy distribution (SED) measurements for the previously known edge-on disks. These can be used as templates to identify new candidates in far-infrared survey datasets.We report on the results of our HST program to image twenty-one edge-on disk candidates mostly selected from their SEDs. Eleven are well-resolved with radii ranging from 30-400 AU, nine for the first time and six showing highly collimated jets. Outstanding individual sources include a large and symmetric new template object, a highly flattened disk not accreting onto its central star, and an asymmetric disk with a misaligned jet which likely traces tidal perturbations in a binary system. Follow-up work to obtain ancillary data and perform scattered light modeling of the most symmetric disks is now being pursued. The results of this program will guide a new round of searches for these rare but important snapshots of protoplanetary disk evolution.

scholarly journals A wide survey for circumstellar disks in the Lupus complex

2020 ◽  
Vol 642 ◽  
pp. A86
Author(s):  
P. S. Teixeira ◽  
A. Scholz ◽  
J. Alves
Keyword(s):  
Three Dimensional ◽  
Circumstellar Disks ◽  
Young Stellar Objects ◽  
Dimensional Structure ◽  
Spectral Energy ◽  
Mass Star ◽  
Nearby Star ◽  
Stellar Objects ◽  
Star Forming ◽  
Low Mass

Previous star formation studies have, out of necessity, often defined a population of young stars confined to the proximity of a molecular cloud. Gaia allows us to examine a wider, three-dimensional structure of nearby star forming regions, leading to a new understanding of their history. We present a wide-area survey covering 494 deg2 of the Lupus complex, a prototypical low-mass star forming region. Our survey includes all known molecular clouds in this region as well as parts of the Upper Scorpius and Upper Centaurus Lupus (UCL) groups of the Sco-Cen complex. We combine Gaia DR2 proper motions and parallaxes as well as ALLWISE mid-infrared photometry to select young stellar objects (YSOs) with disks. The YSO ages are inferred from Gaia color-magnitude diagrams, and their evolutionary stages from the slope of the spectral energy distributions. We find 98 new disk-bearing sources. Our new sample includes objects with ages ranging from 1 to 15 Myr and masses ranging from 0.05 to 0.5 M⊙, and consists of 56 sources with thick disks and 42 sources with anemic disks. While the youngest members are concentrated in the clouds and at distances of 160 pc, there is a distributed population of slightly older stars that overlap in proper motion, spatial distribution, distance, and age with the Lupus and UCL groups. The spatial and kinematic properties of the new disk-bearing YSOs indicate that Lupus and UCL are not distinct groups. Our new sample comprises some of the nearest disks to Earth at these ages, and thus provides an important target for follow-up studies of disks and accretion in very low mass stars, for example with ALMA and ESO-VLT X-shooter.

scholarly journals Disks Around T Tauri Stars with SPHERE (DARTTS-S)

2020 ◽  
Vol 633 ◽  
pp. A82 ◽  
Author(s):  
A. Garufi ◽  
H. Avenhaus ◽  
S. Pérez ◽  
S. P. Quanz ◽  
R. G. van Holstein ◽  
...  
Keyword(s):  
Scattered Light ◽  
Spectral Energy Distribution ◽  
Surrounding Medium ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Spectral Energy ◽  
Near Ir ◽  
Nir Imaging ◽  
T Tauri ◽  
Disk Size

Context. Near-IR polarimetric images of protoplanetary disks enable us to characterize substructures that might be due to the interaction with (forming) planets. The available census is strongly biased toward massive disks around old stars, however. Aims. The DARTTS program aims at alleviating this bias by imaging a large number of T Tauri stars with diverse properties. Methods. DARTTS-S employs VLT/SPHERE to image the polarized scattered light from disks. In parallel, DARTTS-A provides ALMA images of the same targets for a comparison of different dust components. In this work, we present new SPHERE images of 21 circumstellar disks, which is the largest sample released to date. We also recalculated some relevant stellar and disk properties following Gaia DR2. Results. The targets of this work are significantly younger than those published thus far with polarimetric near-IR (NIR) imaging. Scattered light is unambiguously resolved in 11 targets, and some polarized unresolved signal is detected in 3 additional sources. Some disk substructures are detected. However, the paucity of spirals and shadows from this sample reinforces the trend according to which these NIR features are associated with Herbig stars, either because they are older or more massive. Furthermore, disk rings that are apparent in ALMA observations of some targets do not appear to have corresponding detections with SPHERE. Inner cavities larger than ~15 au are also absent from our images, even though they are expected from the spectral energy distribution. On the other hand, 3 objects show extended filaments at larger scale that are indicative of strong interaction with the surrounding medium. All but one of the undetected disks are best explained by their limited size (≲20 au), and the high occurrence of stellar companions in these sources suggests an important role in limiting the disk size. One undetected disk is massive and very large at millimeter wavelengths, implying that it is self-shadowed in the NIR. Conclusions. This work paves the way toward a more complete and less biased sample of scattered-light observations, which is required to interpret how disk features evolve throughout the disk lifetime.

scholarly journals Resolved Scattered Light Images of the Edge-On Protoplanetary Disk ESO Hα 569

2013 ◽  
Vol 8 (S299) ◽  
pp. 76-77
Author(s):  
S. Wolff ◽  
M. Perrin ◽  
K. Stapelfeldt ◽  
G. Duchêne ◽  
J. Krist ◽  
...  
Keyword(s):  
Scattered Light ◽  
Spectral Energy Distribution ◽  
Volume Density ◽  
Protoplanetary Disk ◽  
Young Star ◽  
Outer Radius ◽  
Spectral Energy ◽  
Distribution Data ◽  
Nearby Star ◽  
Star Forming

AbstractWe present detailed models of the edge-on protoplanetary disk ESO Hα 569 (SSTgbs J111110.7-764157) from resolved scattered light images from HST and a complete spectral energy distribution. Data was obtained as part of an HST campaign to catalogue edge-on disks around young stars in nearby star forming regions (HST program 12514, PI: Karl Stapelfeldt). We confirm that this object is an optically thick edge-on disk around a young star with an outer radius of 125 AU. Using full radiative transfer models, we probe the distribution of dust grains and overall shape of the disk (inclination, scale height, dust mass, maximum particle size, inner radius, flaring exponent and surface/volume density exponent).

scholarly journals Ring structure in the MWC 480 disk revealed by ALMA

2019 ◽  
Vol 622 ◽  
pp. A75 ◽  
Author(s):  
Yao Liu ◽  
Giovanni Dipierro ◽  
Enrico Ragusa ◽  
Giuseppe Lodato ◽  
Gregory J. Herczeg ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Surface Density ◽  
Structural Parameters ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Three Dimensional ◽  
Central Star ◽  
Radiative Transfer Model ◽  
Spectral Energy ◽  
Transfer Model

Gap-like structures in protoplanetary disks are likely related to planet formation processes. In this paper, we present and analyze high-resolution (0.17′′× 0.11′′) 1.3 mm ALMA continuum observations of the protoplanetary disk around the Herbig Ae star MWC 480. Our observations show for the first time a gap centered at ~74 au with a width of ~23 au, surrounded by a bright ring centered at ~98 au from the central star. Detailed radiative transfer modeling of the ALMA image and the broadband spectral energy distribution is used to constrain the surface density profile and structural parameters of the disk. If the width of the gap corresponds to 4–8 times the Hill radius of a single forming planet, then the putative planet would have a mass of 0.4–3 MJ. We test this prediction by performing global three-dimensional smoothed particle hydrodynamic gas/dust simulations of disks hosting a migrating and accreting planet. We find that the dust emission across the disk is consistent with the presence of an embedded planet with a mass of ~2.3 MJ at an orbital radius of ~78 au. Given the surface density of the best-fit radiative transfer model, the amount of depleted mass in the gap is higher than the mass of the putative planet, which satisfies the basic condition for the formation of such a planet.

scholarly journals An infrared study of the high-mass, multistage star-forming region IRAS 12272−6240

2020 ◽  
Vol 496 (3) ◽  
pp. 3358-3370
Author(s):  
Mauricio Tapia ◽  
Paolo Persi ◽  
Miguel Roth ◽  
Davide Elia
Keyword(s):  
Near Infrared ◽  
Narrow Band ◽  
Spectral Energy Distribution ◽  
Central Star ◽  
Young Stellar Objects ◽  
High Mass ◽  
Spectral Energy ◽  
H Ii Regions ◽  
Infrared Study ◽  
Star Forming

ABSTRACT IRAS 12272−6240 is a complex star-forming region with a compact massive dense clump (DC) and several associated masers, located at a well-determined distance of d = 9.3 kpc from the Sun. For this study, we obtained sub-arcsec broad- and narrow-band near-infrared (near-IR) imaging and low-resolution spectroscopy with the Baade/Magellan telescope and its camera PANIC. Mosaics of size 2 × 2 arcmin2 in the JHKs bands and with narrow-band filters centred in the 2.12 μm H2 and 2.17 μm Br γ lines were analysed in combination with Hi-GAL/Herschel and archive IRAC/Spitzer and WISE observations. We found that the compact DC houses two Class I young stellar objects (YSOs) that probably form a 21000 -au-wide binary system. Its combined 1–1200 μm spectral energy distribution is consistent with an O9V central star with a $10^{-2} \, \mathrm{M}_\odot$ disc and a $1.3 \times 10^4 \, \mathrm{M}_\odot$ dust envelope. Its total luminosity is $8.5 \times 10^4 \, \mathrm{L}_\odot$. A series of shocked H2 emission knots are found in its close vicinity, confirming the presence of outflows. IRAS 12272−6240 is at the centre of an embedded cluster with a mean age of 1 Myr and 2.6 pc in size that contains more than 150 stars. At its nucleus, we found a more compact and considerably younger subcluster containing the YSOs. We also identified and classified the O-type central stars of two dusty radio/IR H ii regions flanking the protostars. Our results confirm that these elements form a single giant young complex where massive star formation processes started some 1 Myr ago and are still active.

scholarly journals The MUSE Hubble Ultra Deep Field Survey

2018 ◽  
Vol 617 ◽  
pp. A62 ◽  
Author(s):  
Anna Feltre ◽  
Roland Bacon ◽  
Laurence Tresse ◽  
Hayley Finley ◽  
David Carton ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Gas Content ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Space Telescope ◽  
Star Forming ◽  
Neutral Gas ◽  
Near Ultraviolet ◽  
Hubble Ultra Deep Field ◽  
Stellar Masses

The physical origin of the near-ultraviolet Mg II emission remains an underexplored domain, unlike more typical emission lines that are detected in the spectra of star-forming galaxies. We explore the nebular and physical properties of a sample of 381 galaxies between 0.70 < z < 2.34 drawn from the MUSE Hubble Ultra Deep Survey. The spectra of these galaxies show a wide variety of profiles of the Mg II λλ2796, 2803 resonant doublet, from absorption to emission. We present a study on the main drivers for the detection of Mg II emission in galaxy spectra. By exploiting photoionization models, we verified that the emission-line ratios observed in galaxies with Mg II in emission are consistent with nebular emission from HII regions. From a simultaneous analysis of MUSE spectra and ancillary Hubble Space Telescope information through spectral energy distribution fitting, we find that galaxies with Mg II in emission have lower stellar masses, smaller sizes, bluer spectral slopes, and lower optical depth than those with absorption. This leads us to suggest that Mg II emission is a potential tracer of physical conditions that are not merely related to those of the ionized gas. We show that these differences in Mg II emission and absorption can be explained in terms of a higher dust and neutral gas content in the interstellar medium (ISM) of galaxies showing Mg II in absorption, which confirms the extreme sensitivity of Mg II to the presence of the neutral ISM. We conclude with an analogy between the Mg II doublet and the Ly α line that lies in their resonant nature. Further investigations with current and future facilities, including the James Webb Space Telescope, are promising because the detection of Mg II emission and its potential connection with Lyα could provide new insights into the ISM content in the early Universe.

scholarly journals Investigating the young solar system analog HD 95086

2018 ◽  
Vol 617 ◽  
pp. A76 ◽  
Author(s):  
G. Chauvin ◽  
R. Gratton ◽  
M. Bonnefoy ◽  
A.-M. Lagrange ◽  
J. de Boer ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Scattered Light ◽  
Spectral Energy Distribution ◽  
Giant Planet ◽  
Giant Planets ◽  
Dual Band ◽  
Spectral Energy ◽  
Semi Major Axis ◽  
Integral Field Spectrograph

Context. HD 95086 (A8V, 17 Myr) hosts a rare planetary system for which a multi-belt debris disk and a giant planet of 4–5 MJup have been directly imaged. Aims. Our study aims to characterize the global architecture of this young system using the combination of radial velocity and direct imaging observations. We want to characterize the physical and orbital properties of HD 95086 b, search for additional planets at short and wide orbits and image the cold outer debris belt in scattered light. Methods. We used HARPS at the ESO 3.6 m telescope to monitor the radial velocity of HD 95086 over two years and investigate the existence of giant planets at less than 3 au orbital distance. With the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE at VLT, we imaged the faint circumstellar environment beyond 10 au at six epochs between 2015 and 2017. Results. We do not detect additional giant planets around HD 95086. We identify the nature (bound companion or background contaminant) of all point-like sources detected in the IRDIS field of view. None of them correspond to the ones recently discovered near the edge of the cold outer belt by ALMA. HD 95086 b is resolved for the first time in J-band with IFS. Its near-infrared spectral energy distribution is well fitted by a few dusty and/or young L7–L9 dwarf spectral templates. The extremely red 1–4 μm spectral distribution is typical of low-gravity objects at the L/T spectral type transition. The planet’s orbital motion is resolved between January 2015 and May 2017. Together with past NaCo measurements properly re-calibrated, our orbital fitting solutions favor a retrograde low to moderate-eccentricity orbit e = 0.2+0.3−0.2, with a semi-major axis ~52 au corresponding to orbital periods of ~288 yr and an inclination that peaks at i = 141°, which is compatible with a planet-disk coplanar configuration. Finally, we report the detection in polarimetric differential imaging of the cold outer debris belt between 100 and 300 au, consistent in radial extent with recent ALMA 1.3 mm resolved observations.

scholarly journals Multiple dust shells around Herbig Ae/Be stars

1987 ◽  
Vol 122 ◽  
pp. 99-100
Author(s):  
P.S. Thé ◽  
D. N. Dawanas
Keyword(s):  
Main Sequence ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Far Infrared ◽  
Central Star ◽  
Spectral Energy ◽  
Be Stars ◽  
Intermediate Mass ◽  
Dust Shells ◽  
Average Size

Intermediate mass (2 < M/M⊙ < 9) pre-main sequence objects, also named Herbig Ae/Be stars, are known to have excess radiation in the near-infrared. From IRAS o bservations it turns out without doubt (quality 3, high S/N radio), that these objects are very strong far-infrared emitters at 12, 25, 60 and often also at 100 μm. The spectral energy distribution, depicted in Fig. 1 for intermediate mass pre-main sequence stars, show clearly this large excess. From the difference curves it is apparent that this excess radiation is most probably caused by several dust shells. Using very simplified methods it is possible to derive the average temperature of the dust shells (see Thé, Wesselius, Tjin A Djie and Steenman, 1986). If the chemical composition of the mixture of the dust grains and their average size are assumed it is also possible to estimate other characteristics like the distance from the central star and the mass of the dust shells (see Thé, Hageman, Westerlund, Tjin A Djie, 1985).

scholarly journals Hubble Space Telescope Imaging of the Disks and Jets of Taurus Young Stellar Objects

1997 ◽  
Vol 182 ◽  
pp. 355-364 ◽  
Author(s):  
Karl Stapelfeldt ◽  
Christopher J. Burrows ◽  
John E. Krist ◽  
Keyword(s):  
High Spatial Resolution ◽  
Hubble Space Telescope ◽  
Scattered Light ◽  
Young Stellar Objects ◽  
Opening Angle ◽  
Stellar Objects ◽  
Space Telescope ◽  
Spread Function ◽  
Large Opening ◽  
T Tau

We report on Hubble Space Telescope imaging of eleven young stellar objects in the nearby Taurus molecular clouds. The high spatial resolution and stable point spread function of HST reveal important new details of the circumstellar nebulosity of these objects. Three sources (HH 30, FS Tau B, and DG Tau B) are resolved as compact bipolar nebulae without a directly visible star. In all three cases, jet widths near the sources are found to be 50 AU or less. Flattened disk structures are seen in absorption in HH 30 and FS Tau B, and in reflection about GM Aur. Extended envelope structures traced by scattered light are present in HL Tau, T Tau, DG Tau, and FS Tau. The jet in DG Tau exhibits a large opening angle and is already resolved into a bow-like structure less than 3″ from the star.

scholarly journals Energy Distribution of Planetary Nebulae (UV to Radio)

1993 ◽  
Vol 155 ◽  
pp. 99-108
Author(s):  
C.Y. Zhang
Keyword(s):  
Energy Distribution ◽  
Planetary Nebula ◽  
Spectral Energy Distribution ◽  
Planetary Nebulae ◽  
Central Star ◽  
Spectral Energy ◽  
Significant Progress ◽  
Dust Shell ◽  
The Past ◽  
Entire Wavelength Range

The past decade has seen significant progress in our understanding of spectral energy distribution of planetary nebulae over the entire wavelength range from UV to radio. In this review we show the detailed breakdown of the energy budget for a planetary nebula as a system of the three components, i.e., the central star, the gaseous nebula and the dust shell. This picture of the energy distribution is further discussed in the context of planetary nebula evolution.

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