11 research outputs found
Disk masses in the Orion Molecular Cloud-2: distinguishing time and environment
The mass evolution of protoplanetary disks is driven by both internal
processes and external factors, such as photoevaporation. Disentangling these
two effects, however, has remained difficult. We measure the dust masses of a
sample of 132 disks in the Orion Molecular Cloud (OMC)-2 region, and compare
them to (i) externally photoevaporated disks in the Trapezium cluster, and (ii)
disks in nearby low-mass star forming regions (SFRs). This allows us to test if
initial disk properties are the same in high- and low-mass SFRs, and enables a
direct measurement of the effect of external photoevaporation on disks. A ~
mosaic of 3 mm continuum observations from the Atacama Large
Millimeter/submillimeter Array (ALMA) was used to measure the fluxes of 132
disks and 35 protostars >0.5 pc away from the Trapezium. We identify and
characterize a sample of 34 point sources not included in the Spitzer catalog
on which the sample is based. Of the disks, 37 (28%) are detected, with masses
ranging from 7-270 M_e. The detection rate for protostars is higher at 69%.
Disks near the Trapezium are found to be less massive by a factor
, implying a mass loss rate of M_sun/yr.
Our observations allow us to distinguish the impact of time and environment on
disk evolution in a single SFR. The disk mass distribution in OMC-2 is
statistically indistinguishable from that in nearby low-mass SFRs, like Lupus
and Taurus. We conclude that age is the main factor determining the evolution
of these disks. This result is robust with respect to assumptions of dust
temperature, sample incompleteness and biases. The difference between the OMC-2
and Trapezium cluster samples is consistent with mass loss driven by
far-ultraviolet radiation near the Trapezium. Together, this implies that in
isolation, disk formation and evolution proceed similarly, regardless of cloud
mass.Comment: Accepted for publication in A&A. 16 pages, 6 figure
X-ray, Near-Ultraviolet, and Optical Flares Produced By Colliding Magnetospheres in The Young High-Eccentricity Binary DQ Tau
DQ Tau is a unique young high-eccentricity binary system that exhibits
regular magnetic reconnection flares and pulsed accretion near periastron. We
conducted NuSTAR, Swift, and Chandra observations during the July 30, 2022
periastron to characterize X-ray, near-ultraviolet (NUV), and optical flaring
emissions. Our findings confirm the presence of X-ray super-flares accompanied
by substantial NUV and optical flares, consistent with previous discoveries of
periastron flares in 2010 and 2021. These observations, supported by new
evidence, strongly establish the magnetosphere collision mechanism as the
primary driver of magnetic energy release during DQ Tau's periastron flares.
The energetics of the observed X-ray super-flares remain consistent across the
three periastrons, indicating recurring energy sources during each passage,
surpassing the capabilities of single stars. The observed flaring across
multiple bands supports the Adams et al. model for magnetosphere interaction in
eccentric binaries. Evidence from modeling and past and current observations
suggests that both the mm/X-ray periastron flares and tentatively, the magnetic
reconnection-related components of the optical/NUV emissions, conform to the
classical solar/stellar non-thermal thick-target model, except for the
distinctive magnetic energy source. However, our NuSTAR observations suffered
from high background levels, hindering the detection of anticipated non-thermal
hard X-rays. Furthermore, we report serendipitous discovery of X-ray
super-flares occurring away from periastron, potentially associated with
interacting magnetospheres. The current study is part of a broader
multi-wavelength campaign, which is planned to investigate the influence of DQ
Tau's stellar radiation on gas-phase ion chemistry within its circumbinary
disk.Comment: 27 pages, 9 figures, 3 tables. Accepted for publication in The
Astrophysical Journal, October 18, 202
Dust masses of young disks: constraining the initial solid reservoir for planet formation
In recent years evidence has been building that planet formation starts
early, in the first 0.5 Myr. Studying the dust masses available in young
disks enables understanding the origin of planetary systems since mature disks
are lacking the solid material necessary to reproduce the observed exoplanetary
systems, especially the massive ones. We aim to determine if disks in the
embedded stage of star formation contain enough dust to explain the solid
content of the most massive exoplanets. We use Atacama Large
Millimeter/submillimeter Array (ALMA) Band 6 observations of embedded disks in
the Perseus star-forming region together with Very Large Array (VLA) Ka-band (9
mm) data to provide a robust estimate of dust disk masses from the flux
densities. Using the DIANA opacity model including large grains, with a dust
opacity value of = 0.28 cm g, the median dust
masses of the embedded disks in Perseus are 158 M for Class 0 and 52
M for Class I from the VLA fluxes. The lower limits on the median
masses from ALMA fluxes are 47 M and 12 M for Class 0 and
Class I, respectively, obtained using the maximum dust opacity value
= 2.3 cm g. The dust masses of young Class 0
and I disks are larger by at least a factor of 10 and 3, respectively, compared
with dust masses inferred for Class II disks in Lupus and other regions. The
dust masses of Class 0 and I disks in Perseus derived from the VLA data are
high enough to produce the observed exoplanet systems with efficiencies
acceptable by planet formation models: the solid content in observed giant
exoplanets can be explained if planet formation starts in Class 0 phase with an
efficiency of 15%. Higher efficiency of 30% is necessary if the
planet formation is set to start in Class I disks.Comment: 16 pages, 10 figures, accepted for publication in A&
XUE. Molecular inventory in the inner region of an extremely irradiated Protoplanetary Disk
We present the first results of the eXtreme UV Environments (XUE) James Webb
Space Telescope (JWST) program, that focuses on the characterization of planet
forming disks in massive star forming regions. These regions are likely
representative of the environment in which most planetary systems formed.
Understanding the impact of environment on planet formation is critical in
order to gain insights into the diversity of the observed exoplanet
populations. XUE targets 15 disks in three areas of NGC 6357, which hosts
numerous massive OB stars, among which some of the most massive stars in our
Galaxy. Thanks to JWST we can, for the first time, study the effect of external
irradiation on the inner ( au), terrestrial-planet forming regions of
proto-planetary disks. In this study, we report on the detection of abundant
water, CO, CO, HCN and CH in the inner few au of XUE 1, a highly
irradiated disk in NGC 6357. In addition, small, partially crystalline silicate
dust is present at the disk surface. The derived column densities, the
oxygen-dominated gas-phase chemistry, and the presence of silicate dust are
surprisingly similar to those found in inner disks located in nearby,
relatively isolated low-mass star-forming regions. Our findings imply that the
inner regions of highly irradiated disks can retain similar physical and
chemical conditions as disks in low-mass star-forming regions, thus broadening
the range of environments with similar conditions for inner disk rocky planet
formation to the most extreme star-forming regions in our Galaxy.Comment: Accepted for publication in ApJ Letters. 20 pages, 7 figure
X-Ray, Near-ultraviolet, and Optical Flares Produced by Colliding Magnetospheres in the Young High-eccentricity Binary DQ Tau
DQ Tau is a unique young high-eccentricity binary system that exhibits regular magnetic reconnection flares and pulsed accretion near periastron. We conducted NuSTAR, Swift, and Chandra observations during the 2022 July 30 periastron to characterize X-ray, near-ultraviolet (NUV), and optical flaring emissions. Our findings confirm the presence of X-ray superflares accompanied by substantial NUV and optical flares, consistent with previous discoveries of periastron flares in 2010 and 2021. These observations, supported by new evidence, strongly establish the magnetosphere collision mechanism as the primary driver of magnetic energy release during DQ Tau’s periastron flares. The energetics of the observed X-ray superflares remain consistent across the three periastra, indicating recurring energy sources during each passage, surpassing the capabilities of single stars. The observed flaring across multiple bands supports the Adams et al. model for magnetosphere interaction in eccentric binaries. Evidence from modeling and past and current observations suggests that both the millimeter/X-ray periastron flares and, tentatively, the magnetic-reconnection-related components of the optical/NUV emissions conform to the classical solar/stellar nonthermal thick-target model, except for the distinctive magnetic energy source. However, our NuSTAR observations suffered from high background levels, hindering the detection of anticipated nonthermal hard X-rays. Furthermore, we report the serendipitous discovery of X-ray superflares occurring away from periastron, potentially associated with interacting magnetospheres. The current study is part of a broader multiwavelength campaign, which plans to investigate the influence of DQ Tau’s stellar radiation on gas-phase ion chemistry within its circumbinary disk
XUE: Molecular Inventory in the Inner Region of an Extremely Irradiated Protoplanetary Disk
We present the first results of the eXtreme UV Environments (XUE) James Webb Space Telescope (JWST) program, which focuses on the characterization of planet-forming disks in massive star-forming regions. These regions are likely representative of the environment in which most planetary systems formed. Understanding the impact of environment on planet formation is critical in order to gain insights into the diversity of the observed exoplanet populations. XUE targets 15 disks in three areas of NGC 6357, which hosts numerous massive OB stars, including some of the most massive stars in our Galaxy. Thanks to JWST, we can, for the first time, study the effect of external irradiation on the inner (<10 au), terrestrial-planet-forming regions of protoplanetary disks. In this study, we report on the detection of abundant water, CO, 12CO2, HCN, and C2H2 in the inner few au of XUE 1, a highly irradiated disk in NGC 6357. In addition, small, partially crystalline silicate dust is present at the disk surface. The derived column densities, the oxygen-dominated gas-phase chemistry, and the presence of silicate dust are surprisingly similar to those found in inner disks located in nearby, relatively isolated low-mass star-forming regions. Our findings imply that the inner regions of highly irradiated disks can retain similar physical and chemical conditions to disks in low-mass star-forming regions, thus broadening the range of environments with similar conditions for inner disk rocky planet formation to the most extreme star-forming regions in our Galaxy