bluuebunny/crossref_metadata_2025_split huggingface dataset:
JWST Noise Floor. II. Systematic Error Sources in JWST NIRCam Time Series
Authors: Schlawin Everett , Leisenring Jarron , McElwain Michael W. , Misselt Karl , Don Kenneth , Greene Thomas P. , Beatty Thomas , Nikolov Nikolay , Kelly Douglas , Rieke Marcia 
Published: February 2021

Abstract
The James Webb Space Telescope (JWST) holds great promise for characterizing atmospheres of transiting exoplanets, potentially providing insights into Earth-sized planets within the habitable zones of M-dwarf host stars if photon-limited performance can be achieved. Here, we discuss the systematic error sources that are expected to be present in grism time-series observations with the NIRCam instrument. We find that pointing jitter and high-gain antenna moves in addition to the detectors’ subpixel crosshatch patterns will produce relatively small variations (less than 6 parts per million, ppm). The time-dependent aperture losses due to thermal instabilities in the optics can also be kept to below 2 ppm. To achieve these low noise values, it is important to employ a sufficiently large (more than 11) extraction aperture. Persistence due to charge-trapping will have a minor (less than 3 ppm) effect on the time series 20 minutes into an exposure and is expected to play a much smaller role than it does for the Hubble Space Telescope WFC3 detectors. We expect detector temperature fluctuations to contribute less than 3 ppm. In total, our estimated noise floor from known systematic error sources is only 9 ppm per visit. We urge caution, however, because unknown systematic error sources could be present in flight and will only be measurable on astrophysical sources such as quiescent stars. We find that reciprocity failure may introduce a perennial instrument offset at the 40 ppm level, so corrections may be needed when a multi-instrument multi-observatory spectrum is stitched together over wide wavelength ranges.
Initial Characterization of Active Transitioning Centaur, P/2019 LD2 (ATLAS), Using Hubble, Spitzer, ZTF, Keck, Apache Point Observatory, and GROWTH Visible and Infrared Imaging and Spectroscopy
Authors: Bolin Bryce T. , Fernandez Yanga R. , Lisse Carey M. , Holt Timothy R. , Lin Zhong-Yi , Purdum Josiah N. , Deshmukh Kunal P. , Bauer James M. , Bellm Eric C. , Bodewits Dennis , Burdge Kevin B. , Carey Sean J. , Copperwheat Chris M. , Helou George , Ho Anna Y. Q. , Horner Jonathan , Roestel Jan van , Bhalerao Varun , Chang Chan-Kao , Chen Christine , Hsu Chen-Yen , Ip Wing-Huen , Kasliwal Mansi M. , Masci Frank J. , Ngeow Chow-Choong , Quimby Robert , Burruss Rick , Coughlin Michael , Dekany Richard , Delacroix Alexandre , Drake Andrew , Duev Dmitry A. , Graham Matthew , Hale David , Kupfer Thomas , Laher Russ R. , Mahabal Ashish , Mróz Przemyslaw J. , Neill James D. , Riddle Reed , Rodriguez Hector , Smith Roger M. , Soumagnac Maayane T. , Walters Richard , Yan Lin , Zolkower Jeffry 
Published: February 2021

Abstract
We present visible and mid-infrared imagery and photometry of temporary Jovian co-orbital comet P/2019 LD2 taken with Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3), Spitzer Space Telescope/Infrared Array Camera (Spitzer/IRAC), and the GROWTH telescope network, visible spectroscopy from Keck/Low-Resolution Imaging Spectrometer (LRIS), and archival Zwicky Transient Facility observations taken between 2019 April and 2020 August. Our observations indicate that the nucleus of LD2 has a radius between 0.2 and 1.8 km assuming a 0.08 albedo and a coma dominated by ∼100 μm-scale dust ejected at ∼1 m s−1 speeds with a ∼1′ jet pointing in the southwest direction. LD2 experienced a total dust mass loss of ∼108 kg at a loss rate of ∼6 kg s−1 with Afρ/cross section varying between ∼85 cm/125 km2 and ∼200 cm/310 km2 from 2019 April 9 to 2019 November 8. If the increase in Afρ/cross section remained constant, it implies LD2's activity began ∼2018 November when within 4.8 au of the Sun, implying the onset of H2O sublimation. We measure CO/CO2 gas production of ≲1027 mol s−1/≲1026 mol s−1 from our 4.5 μm Spitzer observations; g–r = 0.59 ± 0.03, r–i = 0.18 ± 0.05, and i–z = 0.01 ± 0.07 from GROWTH observations; and H2O gas production of ≲80 kg s−1 scaling from our estimated C
2 production of

mol s−1 from Keck/LRIS spectroscopy. We determine that the long-term orbit of LD2 is similar to Jupiter-family comets having close encounters with Jupiter within ∼0.5 Hill radius in the last ∼3 y and within 0.8 Hill radius in ∼9 y. Additionally, 78.8% of our orbital clones are ejected from the solar system within 1 × 106 yr, having a dynamical half-life of 3.4 × 105 yr.
Characteristics of Magnetic Holes in the Solar Wind Revealed by Parker Solar Probe
Authors: Yu L. , Huang S. Y. , Yuan Z. G. , Jiang K. , Xiong Q. Y. , Xu S. B. , Wei Y. Y. , Zhang J. , Zhang Z. H. 
Published: February 2021

Abstract
We present a statistical analysis for the characteristics and radial evolution of linear magnetic holes (LMHs) in the solar wind from 0.166 to 0.82 au using Parker Solar Probe observations of the first two orbits. It is found that the LMHs mainly have a duration less than 25 s and the depth is in the range from 0.25 to 0.7. The durations slightly increase and the depths become slightly deeper with the increasing heliocentric distance. Both the plasma temperature and the density for about 50% of all events inside the holes are higher than the ones surrounding the holes. The average occurrence rate is 8.7 events day−1, much higher than that of the previous observations. The occurrence rate of the LMHs has no clear variation with the heliocentric distance (only a slight decreasing trend with the increasing heliocentric distance), and has several enhancements around ∼0.525 and ∼0.775 au, implying that there may be new locally generated LMHs. All events are segmented into three parts (i.e., 0.27, 0.49, and 0.71 au) to investigate the geometry evolution of the linear magnetic holes. The results show that the geometry of LMHs are prolonged both across and along the magnetic field direction from the Sun to the Earth, while the scales across the field extend a little faster than along the field. The present study could help us understand the evolution and formation mechanism of the LMHs in the solar wind.
ALMA Measures Rapidly Depleted Molecular Gas Reservoirs in Massive Quiescent Galaxies at z ∼ 1.5
Authors: Williams Christina C. , Spilker Justin S. , Whitaker Katherine E. , Davé Romeel , Woodrum Charity , Brammer Gabriel , Bezanson Rachel , Narayanan Desika , Weiner Benjamin 
Published: February 2021

Abstract
We present Atacama Large Millimeter/submillimeter Array (ALMA) CO(2–1) spectroscopy of six massive (log10

/

> 11.3) quiescent galaxies at z ∼ 1.5. These data represent the largest sample using CO emission to trace molecular gas in quiescent galaxies above z > 1, achieving an average 3σ sensitivity of

∼ 1010

. We detect one galaxy at 4σ significance and place upper limits on the molecular gas reservoirs of the other five, finding molecular gas mass fractions

(3σ upper limits). This is 1–2 orders of magnitude lower than coeval star-forming galaxies at similar stellar mass, and comparable to galaxies at z = 0 with similarly low specific star formation rate (sSFR). This indicates that their molecular gas reservoirs were rapidly and efficiently used up or destroyed, and that gas fractions are uniformly low (<6%) despite the structural diversity of our sample. The implied rapid depletion time of molecular gas (

< 0.6 Gyr) disagrees with extrapolations of empirical scaling relations to low sSFR. We find that our low gas fractions are instead in agreement with predictions from both the recent simba cosmological simulation, and from analytical “bathtub” models for gas accretion onto galaxies in massive dark matter halos (log

at z = 0). Such high mass halos reach a critical mass of log

by z ∼ 4 that halt the accretion of baryons early in the universe. Our data are consistent with a simple picture where galaxies truncate accretion and then consume the existing gas at or faster than typical main-sequence rates. Alternatively, we cannot rule out that these galaxies reside in lower mass halos, and low gas fractions may instead reflect either stronger feedback, or more efficient gas consumption.
Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions
Authors: Schippers Stefan , Beerwerth Randolf , Bari Sadia , Buhr Ticia , Holste Kristof , Kilcoyne A. L. David , Perry-Sassmannshausen Alexander , Phaneuf Ronald A. , Reinwardt Simon , Savin Daniel Wolf , Schubert Kaja , Fritzsche Stephan , Martins Michael , Müller Alfred 
Published: February 2021

Abstract
Using the photon–ion merged-beams technique at a synchrotron light source, we have measured relative cross sections for single and up to five-fold photoionization of Fe2+ ions in the energy range of 690–920 eV. This range contains thresholds and resonances associated with ionization and excitation of 2p and 2s electrons. Calculations were performed to simulate the total absorption spectra. The theoretical results show very good agreement with the experimental data, if overall energy shifts of up to 2.5 eV are applied to the calculated resonance positions and assumptions are made about the initial experimental population of the various levels of the Fe2+([Ar]3d
6) ground configuration. Furthermore, we performed extensive calculations of the Auger cascades that result when an electron is removed from the 2p subshell of Fe2+. These computations lead to a better agreement with the measured product-charge-state distributions as compared to earlier work. We conclude that the L-shell absorption features of low-charged iron ions are useful for identifying gas-phase iron in the interstellar medium and for discriminating against the various forms of condensed-phase iron bound to composite interstellar dust grains.
Early-time Light Curves of Type Ia Supernovae Observed with TESS
Authors: Fausnaugh M. M. , Vallely P. J. , Kochanek C. S. , Shappee B. J. , Stanek K. Z. , Tucker M. A. , Ricker George R. , Vanderspek Roland , Latham David W. , Seager S. , Winn Joshua N. , Jenkins Jon M. , Berta-Thompson Zachory K. , Daylan Tansu , Doty John P. , Fűrész Gábor , Levine Alan M. , Morris Robert , Pál András , Sha Lizhou , Ting Eric B. , Wohler Bill 
Published: February 2021

Abstract
We present the early-time light curves of Type Ia supernovae (SNe Ia) observed in the first six sectors of Transiting Exoplanet Survey Satellite (TESS) data. Ten of these SNe were discovered by ASAS-SN, seven by ATLAS, six by ZTF, and one by Gaia. For nine of these objects with sufficient dynamic range (>3.0 mag from detection to peak), we fit power-law models and searched for signatures of companion stars. We found a diversity of early-time light-curve shapes, although most of our sources are consistent with fireball models where the flux increases as ∝t
2. Three SNe displayed a flatter rise with flux ∝t. We did not find any obvious evidence for additional structures, such as multiple power-law components, in the early rising light curves. For assumptions about the SN properties and the observer viewing angle (ejecta mass of 1.4 M
⊙, expansion velocity of 104 km s−1, opacity of 0.2 cm2 g−1, and viewing angle of 45°) and a further assumption that any companion stars would be in Roche lobe overflow, it is possible to place upper limits on the radii of any companion stars. Six of the nine SNe had complete coverage of the early-time light curves, and we placed upper limits on the radii of companion stars of ≲32 R
⊙ for these SNe, ≲20 R
⊙ for five of the six, and ≲4 R
⊙ for two of the six. The small sample size did not allow us to put limits on the occurrence rate of companion stars in the progenitors of SNe Ia. However, we expect that TESS observed enough SNe in its two-year primary mission (26 sectors) to either detect the signature of a large companion (R > 20 R
⊙) or constrain the occurrence rate of such systems, at least for the fiducial SN properties adopted here. We also show that TESS is capable of detecting emission from a 1 R
⊙ companion for an SN Ia within 50 Mpc and has a reasonable chance of doing so after about six years.
Dynamical Stellar Masses of Pre-main-sequence Stars in Lupus and Taurus Obtained with ALMA Surveys in Comparison with Stellar Evolutionary Models
Authors: Braun Teresa A. M. , Yen Hsi-Wei , Koch Patrick M. , Manara Carlo F. , Miotello Anna , Testi Leonardo 
Published: February 2021

Abstract
We analyzed archival molecular line data of pre-main-sequence (PMS) stars in the Lupus and Taurus star-forming regions obtained with ALMA surveys with an integration time of a few minutes per source. We stacked the data of 13CO and C18O (J = 2–1 and 3–2) and CN (N = 3–2, J = 7/2–5/2) lines to enhance the signal-to-noise ratios and measured the stellar masses of 45 out of 67 PMS stars from the Keplerian rotation in their circumstellar disks. The measured dynamical stellar masses were compared to the stellar masses estimated from the spectroscopic measurements with seven different stellar evolutionary models. We found that the magnetic model of Feiden provides the best estimate of the stellar masses in the mass range of 0.6 M
⊙ ≤ M
⋆ ≤ 1.3 M
⊙ with a deviation of <0.7σ from the dynamical masses, while all the other models underestimate the stellar masses in this mass range by 20%–40%. In the mass range of <0.6 M
⊙, the stellar masses estimated with the magnetic model of Feiden have a larger deviation (>2σ) from the dynamical masses, and other, nonmagnetic stellar evolutionary models of Siess et al., Baraffe et al., and Feiden show better agreement with the dynamical masses with the deviations of 1.4σ–1.6σ. Our results show the mass dependence of the accuracy of these stellar evolutionary models.
Stochastic Parker Spirals in the Solar Wind
Authors: Bian N. H. , Li G. 
Published: February 2021

Abstract
An analytic model for the angular dispersion of magnetic field lines resulting from the turbulence in the solar wind and at the solar source surface is presented. The heliospheric magnetic field lines in our model are derived from a Hamiltonian

with the pair of canonically conjugated variables the cosine of the heliographic colatitude μ and the longitude ϕ. In the diffusion approximation, the Parker spirals are modeled by a set of stochastic differential equations for θ and ϕ as functions of r. These stochastic Parker spirals are realizations of a standard random walk on a sphere of increasing radius, superimposed on an angular drift due to solar rotation. The Green function solution of the Fokker–Planck equation describing the angular diffusion of the field line density is obtained in terms of spherical harmonics. Magnetic field lines traced from an observer back to the Sun are realizations of a Brownian bridge. Our model incorporates the effect of the random footpoint motions at the source surface, which is associated with the zero-frequency component of the solar wind turbulence. Assuming that the footpoint motion is diffusive, its contribution to the angular diffusivity of the stochastic Parker spirals is then given by the angular diffusivity of the footpoints divided by the solar wind speed and is controlled by a unique parameter, which is the Kubo number.
Imaging Titan’s Organic Haze at Atomic Scale
Authors: Schulz Fabian , Maillard Julien , Kaiser Katharina , Schmitz-Afonso Isabelle , Gautier Thomas , Afonso Carlos , Carrasco Nathalie , Gross Leo 
Published: February 2021

Abstract
Titan, Saturn’s largest moon, has its atmosphere filled with a thick organic photochemical haze. These suspended solid nanoparticles are one of the most complex organic materials in the Solar System. In situ measurements from the successful Cassini space mission gave first clues on the aerosol's chemical composition: pyrolysis coupled to mass spectrometry revealed a nitrogen-rich core, whereas infrared measurements highlighted poly-aromatic-hydrocarbon (PAH) signatures. The combination of these observations supports a general model of nitrogenated-polycyclic aromatic hydrocarbon (N-PAH). To constrain the generic picture and understand the formation of such macromolecules in Titan’s atmosphere, we simulated the haze synthesis in the laboratory. Small (3–10 rings) N-PAH molecules composing the material were extracted, focusing on the prime aromatization and growth processes. By high-resolution atomic force microscopy (AFM), we imaged key chemical structures with atomic resolution. We resolved N-rich elongated molecules involving five-membered aromatic rings, consistent with a repetitive cata-condensation pattern via addition of C3N units. These atomic-scale observations bridge the gap between gas phase atmospheric reactants and the macroscopic structure of Titan’s haze.
The Main Sequence View of Quasars Accreting at High Rates: Influence of Star Formation*
Authors: Marziani Paola , Sniegowska Marzena , Panda Swayamtrupta , Czerny Bożena , Negrete C. Alenka , Dultzin Deborah , Garnica Karla , Martínez-Aldama Mary Loli , del Olmo Ascensión , D’Onofrio Mauro , Machado Alice Deconto , Ganci Valerio ,   (The extreme team)
Published: February 2021

Abstract
Highly accreting quasars show fairly distinctive properties in their optical, UV, and X spectra, and are easy to recognize because of their specific location in the quasar main sequence: they are the strongest optical FeII emitters. They show a surprisingly high rate of radio detections and, at variance with the classical radio-loud (jetted) sources, the origin of their radio emission is probably “thermal.” The chemical composition of the broad line emitting gas implies high metallicity values, above 10 times solar. A fraction of highly accreting quasars at intermediate and high redshift might therefore be in a particular evolutionary stage that is unobscured albeit still involving a contribution of nuclear and circum-nuclear star formation in their multifrequency properties.
Lower Bounds on the Thickness and Dust Content of Layers within the North Polar Layered Deposits of Mars from Radar Forward Modeling
Authors: Courville Samuel W. , Perry Matthew R. , Putzig Nathaniel E. 
Published: February 2021

Abstract
The Mars Reconnaissance Orbiter's Shallow Radar (SHARAD) emits radar signals and records their reflections from layer boundaries within the Martian north polar ice cap. Previous studies have suggested that the ice cap is composed of thin dust-rich layers between thicker layers of nearly pure water ice. The prevailing hypotheses suggest that each dust-rich layer represents either a period of ice sublimation at the poles or a period of reduced ice deposition relative to dust deposition. To test whether thin dust beds are a plausible hypothesis for the observed SHARAD reflectors, we use RadSPy (radar sounding simulator in Python, https://github.com/scourvil/RadSPy.git), an open-source N-layer radar sounder forward-modeling software that we have developed and describe herein. We forward model radar data from thin dust-rich beds interspersing pure ice, and compare them to observed radar reflection data over Gemina Lingula in the north polar layered deposits (NPLD). We consider two end-member cases: (1) thin beds composed entirely of dust, but with thickness varying from 0.05 m to 0.4 m; and (2) dust beds all with the same thickness, but with varying dust content. We find that the observed reflections can be explained by either scenario, i.e., varying thickness or varying dust content, and we conclude that a combination of both is likely. More importantly, our results provide lower bounds on the layer thickness and dust fraction for the flat-lying reflectors of Gemina Lingula in the NPLD. Our findings support the thin dust layer hypothesis, providing new constraints on layer composition and geometry for Mars climate researchers.
Understanding and Advancing Organizational Health Literacy Within a Public Health Setting
Authors: Kružliaková Natalie , Porter Kathleen , Ray Pamela A. , Hedrick Valisa , Brock Donna Jean , Zoellner Jamie 
Published: February 2021

Background:
Organizational health literacy (OHL) within the public health setting is lacking.

Objective:
The aim of this study was to form a health literacy (HL) improvement team consisting of university researchers and Virginia Department of Health (VDH) district directors and staff to assess and improve OHL practices of VDH staff in four medically underserved health districts in southwest Virginia.

Methods:
The Agency for Healthcare Research and Quality Health Literacy Universal Precautions Toolkit guided this mixed-methods needs assessment and improvement plan. VDH staff completed a 44-item survey adapted from this Toolkit and a roundtable discussion to indicate their perceptions of current OHL practices. VDH clients completed a survey including seven items measuring perceptions of staff OHL practices and three items measuring subjective HL.

Key Results:

About one-half of VDH staff (
n
= 252, 88% female, average age 49 ± 12 years, 23% ≤ high school education [HS]) reported “doing well” across all OHL domains. Staff survey and roundtable discussion revealed the need to strengthen the written communication domain. Among 185 VDH clients (82% female, average age 33 ± 14 years, 40% ≤ HS), perceptions of staff OHL practices were high, ranging from 3.07 to 3.64 (scale of 1–4). Client HL status was significantly positively correlated (
p
< .01–.05) with 5 of 7 OHL practices. Findings aided development and initial implementation of an OHL improvement plan, including e-newsletters and in-person workshops. On average, 60% of staff opened quarterly e-newsletters. Staff ratings of the Clear Communication Index workshop were high in terms of utility and applicability of content.

Conclusions:

Results reflected notable strengths and weaknesses in current OHL practices from staff and client perspectives, with the greatest need identified in written communication. E-newsletter series and in-person workshops on the Clear Communication Index helped lay groundwork for additional HL improvement activities for VDH staff. Limitations and future recommendations for public health settings are discussed.

[
HLRP: Health Literacy Research and Practice
. 2021;5(1):e35–e48.]

Plain Language Summary:
This study describes use of the Agency for Healthcare Research and Quality Health Literacy Universal Precautions Toolkit to conduct an organizational health literacy needs assessment and improvement plan in a public health setting, the Virginia Department of Health. Assessment of staff and clients revealed strengths and weaknesses in organizational health literacy practices. Feedback guided efforts to improve organizational health literacy capacity.