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Title: Xenon in the protoplanetary disk (PPD-XE)

Abstract

Relationships among solar system Xe components as observed in the solar wind (SW), in planetary atmospheres and in meteorites are investigated using isotopic correlations. The term PPD-Xe is used for components inferred to have been present in the molecular cloud material that formed the protoplanetary disk (PPD). The evidence of the lack of simple relationships between terrestrial atmospheric Xe and solar or meteoritic components is confirmed. Xe isotopic correlations indicate a heterogeneous PPD composition with variable mixing ratios of the nucleosynthetic component Xe-HL. Solar Xe represents a bulk PPD component, and the isotopic abundances did not change from the time of incorporation into the interior of Mars, through times of regolith implantations to the present.

Authors:
 [1];  [2]
  1. Univ. of California, San Diego, CA (United States). Dept. of Chemistry and Biochemistry
  2. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL), F/H Area Analytical Labs.
Publication Date:
Research Org.:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1226217
Report Number(s):
SRNL-STI-2015-00217
Journal ID: ISSN 2041-8213
Grant/Contract Number:
AC09-08SR22470
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 806; Journal Issue: 2; Journal ID: ISSN 2041-8213
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS

Citation Formats

Marti, K., and Mathew, K. J. Xenon in the protoplanetary disk (PPD-XE). United States: N. p., 2015. Web. doi:10.1088/2041-8205/806/2/L30.
Marti, K., & Mathew, K. J. Xenon in the protoplanetary disk (PPD-XE). United States. doi:10.1088/2041-8205/806/2/L30.
Marti, K., and Mathew, K. J. Thu . "Xenon in the protoplanetary disk (PPD-XE)". United States. doi:10.1088/2041-8205/806/2/L30. https://www.osti.gov/servlets/purl/1226217.
@article{osti_1226217,
title = {Xenon in the protoplanetary disk (PPD-XE)},
author = {Marti, K. and Mathew, K. J.},
abstractNote = {Relationships among solar system Xe components as observed in the solar wind (SW), in planetary atmospheres and in meteorites are investigated using isotopic correlations. The term PPD-Xe is used for components inferred to have been present in the molecular cloud material that formed the protoplanetary disk (PPD). The evidence of the lack of simple relationships between terrestrial atmospheric Xe and solar or meteoritic components is confirmed. Xe isotopic correlations indicate a heterogeneous PPD composition with variable mixing ratios of the nucleosynthetic component Xe-HL. Solar Xe represents a bulk PPD component, and the isotopic abundances did not change from the time of incorporation into the interior of Mars, through times of regolith implantations to the present.},
doi = {10.1088/2041-8205/806/2/L30},
journal = {The Astrophysical Journal. Letters},
number = 2,
volume = 806,
place = {United States},
year = {Thu Jun 18 00:00:00 EDT 2015},
month = {Thu Jun 18 00:00:00 EDT 2015}
}

Journal Article:
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  • Relationships among solar system Xe components as observed in the solar wind, in planetary atmospheres, and in meteorites are investigated using isotopic correlations. The term PPD-Xe is used for components inferred to have been present in the molecular cloud material that formed the protoplanetary disk (PPD). The evidence of the lack of simple relationships between terrestrial atmospheric Xe and solar or meteoritic components is confirmed. Xe isotopic correlations indicate a heterogeneous PPD composition with variable mixing ratios of the nucleosynthetic component Xe-HL. Solar Xe represents a bulk PPD component, and the isotopic abundances did not change from the time ofmore » incorporation into the interior of Mars through times of regolith implantations to the present.« less
  • Chemistry plays an important role in the structure and evolution of protoplanetary disks, with implications for the composition of comets and planets. This is the first of a series of papers based on data from DISCS, a Submillimeter Array survey of the chemical composition of protoplanetary disks. The six Taurus sources in the program (DM Tau, AA Tau, LkCa 15, GM Aur, CQ Tau, and MWC 480) range in stellar spectral type from M1 to A4 and offer an opportunity to test the effects of stellar luminosity on the disk chemistry. The disks were observed in 10 different lines atmore » {approx}3'' resolution and an rms of {approx}100 mJy beam{sup -1} at {approx}0.5 km s{sup -1}. The four brightest lines are CO 2-1, HCO{sup +} 3-2, CN 2{sub 33/4/2} - 1{sub 22/3/1}, and HCN 3-2, and these are detected toward all sources (except for HCN toward CQ Tau). The weaker lines of CN 2{sub 22}-1{sub 11}, DCO{sup +} 3-2, N{sub 2}H{sup +} 3-2, H{sub 2}CO 3{sub 03}-2{sub 02}, and 4{sub 14}-3{sub 13} are detected toward two to three disks each, and DCN 3-2 only toward LkCa 15. CH{sub 3}OH 4{sub 21}-3{sub 1} {sub 2} and c-C{sub 3}H{sub 2} are not detected. There is no obvious difference between the T Tauri and Herbig Ae sources with regard to CN and HCN intensities. In contrast, DCO{sup +}, DCN, N{sub 2}H{sup +}, and H{sub 2}CO are detected only toward the T Tauri stars, suggesting that the disks around Herbig Ae stars lack cold regions for long enough timescales to allow for efficient deuterium chemistry, CO freeze-out, and grain chemistry.« less
  • We present Spitzer 3.6-24 {mu}m photometry and spectroscopy for stars in the 1-3 Myr old Coronet Cluster, expanding upon the survey of Sicilia-Aguilar et al. Using sophisticated radiative transfer models, we analyze these new data and those from Sicilia-Aguilar et al. to identify disks with evidence for substantial dust evolution consistent with disk clearing: transitional disks. We then analyze data in Taurus and others young clusters-IC 348, NGC 2362, and {eta} Cha-to constrain the transitional disk frequency as a function of time. Our analysis confirms previous results finding evidence for two types of transitional disks-those with inner holes and thosemore » that are homologously depleted. The percentage of disks in the transitional phase increases from {approx}15%-20% at 1-2 Myr to {>=}50% at 5-8 Myr; the mean transitional disk lifetime is closer to {approx}1 Myr than 0.1-0.5 Myr, consistent with previous studies by Currie et al. and Sicilia-Aguilar et al. In the Coronet Cluster and IC 348, transitional disks are more numerous for very low mass M3-M6 stars than for more massive K5-M2 stars, while Taurus lacks a strong spectral-type-dependent frequency. Assuming standard values for the gas-to-dust ratio and other disk properties, the lower limit for the masses of optically thick primordial disks is M{sub disk} {approx} 0.001-0.003 M{sub *}. We find that single color-color diagrams do not by themselves uniquely identify transitional disks or primordial disks. Full spectral energy distribution modeling is required to accurately assess disk evolution for individual sources and inform statistical estimates of the transitional disk population in large samples using mid-IR colors.« less
  • This is the second in a series of papers based on data from DISCS, a Submillimeter Array observing program aimed at spatially and spectrally resolving the chemical composition of 12 protoplanetary disks. We present data on six Southern sky sources-IM Lup, SAO 206462 (HD 135344b), HD 142527, AS 209, AS 205, and V4046 Sgr-which complement the six sources in the Taurus star-forming region reported previously. CO 2-1 and HCO{sup +} 3-2 emission are detected and resolved in all disks and show velocity patterns consistent with Keplerian rotation. Where detected, the emission from DCO{sup +} 3-2, N{sub 2}H{sup +} 3-2, H{submore » 2}CO 3{sub 03} - 2{sub 02} and 4{sub 14} - 3{sub 13}, HCN 3-2, and CN 2{sub 33/4/2} - 1{sub 22/3/1} are also generally spatially resolved. The detection rates are highest toward the M and K stars, while the F star SAO 206462 has only weak CN and HCN emission, and H{sub 2}CO alone is detected toward HD 142527. These findings together with the statistics from the previous Taurus disks support the hypothesis that high detection rates of many small molecules depend on the presence of a cold and protected disk midplane, which is less common around F and A stars compared to M and K stars. Disk-averaged variations in the proposed radiation tracer CN/HCN are found to be small, despite a two orders of magnitude range of spectral types and accretion rates. In contrast, the resolved images suggest that the CN/HCN emission ratio varies with disk radius in at least two of the systems. There are no clear observational differences in the disk chemistry between the classical/full T Tauri disks and transitional disks. Furthermore, the observed line emission does not depend on the measured accretion luminosities or the number of infrared lines detected, which suggests that the chemistry outside of 100 AU is not coupled to the physical processes that drive the chemistry in the innermost few AU.« less
  • We present high-resolution H-band polarized intensity (FWHM = 0.''1: 14 AU) and L'-band imaging data (FWHM = 0.''11: 15 AU) of the circumstellar disk around the weak-lined T Tauri star PDS 70 in Centaurus at a radial distance of 28 AU (0.''2) up to 210 AU (1.''5). In both images, a giant inner gap is clearly resolved for the first time, and the radius of the gap is {approx}70 AU. Our data show that the geometric center of the disk shifts by {approx}6 AU toward the minor axis. We confirm that the brown dwarf companion candidate to the north ofmore » PDS 70 is a background star based on its proper motion. As a result of spectral energy distribution fitting by Monte Carlo radiative transfer modeling, we infer the existence of an optically thick inner disk at a few AU. Combining our observations and modeling, we classify the disk of PDS 70 as a pre-transitional disk. Furthermore, based on the analysis of L'-band imaging data, we put an upper limit of {approx}30 to {approx}50 M{sub J} on the mass of companions within the gap. Taking into account the presence of the large and sharp gap, we suggest that the gap could be formed by dynamical interactions of sub-stellar companions or multiple unseen giant planets in the gap.« less