1,720,987 research outputs found
Animations: The Photospheric Footpoints of Solar Coronal Hole Jets
No full textThis repository provides the individual animations of the SDO/AIA and HMI magnetograms of Jets 1, 2, 3, corresponding to jets 14, 32, 35 in Table 1 of the accepted manuscript, "The Photospheric Footpoints of Solar Coronal Hole Jets".
jet1-aia193.mp4: AIA 193A movie of Jet 1
jet1-hmimag.mp4: HMI magnetograms movie of Jet 1
jet1-aia193-hmi-contour.mp4: AIA 193A with HMI contours movie of Jet 1
fig1anim.mp4: Concatenation of Jet 1 movies shown in Figure 1 of the accepted manuscript.
jet2-aia193.mp4: AIA 193A movie of Jet 2
jet2-hmimag.mp4: HMI magnetograms movie of Jet 2
jet2-aia193-hmi-contour.mp4: AIA 193A with HMI contours movie of Jet 2
fig4anim.mp4: Concatenation of Jet 2 movies shown in Figure 4 of the accepted manuscript.
jet3-aia193.mp4: AIA 193A movie of Jet 3
jet3-aia304.mp4: AIA 304A movie of Jet 3
jet3-hmimag.mp4: HMI magnetograms movie of Jet 3
jet3-aia193-hmi-contour.mp4: AIA 193A with HMI contours movie of Jet 3
fig6anim.mp4: Concatenation of Jet 3 movies shown in Figure 6 of the accepted manuscript.This work has been supported by NSF (AGS-1159353) and NASA (project 80NSSC18K0716). AIA and HMI data are courtesy of NASA/SDO and the AIA and HMI science teams. The author would like to thank P.R. Young for the analysis of the EIS data. This research has made use of NASA's Astrophysics Data System
Tables for: The Panchromatic Hubble Andromeda Treasury XXI. The Legacy Resolved Stellar Photometry Catalog
No full textThis deposit contains the full machine-readable tables for the accepted version of the manuscript, "The Panchromatic Hubble Andromeda Treasury XXI. The Legacy Resolved Stellar Photometry Catalog", submitted and accepted to the Astrophysical Journal Supplments.
The specific files included in this deposit are the full version of Tables 1-3 in this manuscript:
Table 1: Simplified table of PHAT photometry for easy use;
Table 2: Simplified table of artificial star test results for easy use;
Table 3: Summary of artificial star statistics as a function of brightness and stellar density.
The *.txt files are formatted according to the machine-readable standards adopted by the AAS Journals and CDS/Vizier. Documentation of this format can be found at these links:
AAS Journals MRT overview
CDS/Vizier standards
These files can be read in python using the astropy package or with the most recent version of TOPCAT (> Version 4.8). An example script for reading these files in astropy is given here:
from astropy.table import Table
data = Table.read("datafile3.txt", format="ascii.cds")
In addition, a headerless, compressed TeX (&-delimited; "full_table.tex.xz") version of Table 1, and a header-only, dataless version of Table 1 ("datafile1_headeronly.txt") are provided to give users additional tools for dealing with this large dataset.
The compression routine was applied using xz with the encodings
xz -z -7 -T 0 full_table.tex
xz -z -9 -T 0 datafile1.txt
The Table 1 files on Zenodo were then split into smaller chunks to upload them to Zenodo using the GNU split routine. The full files can be recovered by recombining them before decompressing them. The list of related commands and the expected md5 hexidecimal checksums are given here:
split --bytes=512M ../full_table.tex.xz full_table.tex.xz.
split --bytes=512M ../datafile1.txt.xz datafile1.txt.xz.
cat full_table.tex.xz.a* > full_table.tex.xz
cat datafile1.txt.xz.a* > datafile1.txt.xz
MD5 (full_table.tex.xz) = 7f9195210bec61c08d04926ada4a021a
MD5 (datafile1.txt.xz) = 63205fe1051e97f4e04380dd23469893
Finally, those interested in generating their own cuts from the DOLPHOT quality parameters can access the full photometry tables, available at MAST as a High Level Science Product via doi.org/10.17909/T91S30The MRT versions of Tables 2 and 3 are also available through the published article. The MRT version of Table 1 (datafile1.txt) is only available at this deposit due to its size.
Support for this work was provided by NASA through grant GO-12055 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Exploring the Possibility of Identifying Hydride and Hydroxyl Cations of Noble Gas Species in the Crab Nebula Filament
Full text linkThe first identification of the argonium ion (ArH+) toward the Crab Nebula supernova remnant was proclaimed by Herschel in the submillimeter and far-infrared domains. Very recently, the discovery of the hydro-helium cation (HeH+) in the planetary nebula (NGC 7027) by SOFIA has been reported. The elemental abundance of neon is much higher than that of argon. However, the presence of neonium ions (NeH+) is yet to be confirmed in space. Though the hydroxyl radicals (-OH) are very abundant in both neutral and cationic forms, hydroxyl cations of such noble gases (i.e., ArOH+, NeOH+, and HeOH+) are yet to be identified in space. Here, we employ a spectral synthesis code to examine the chemical evolution of the hydride and hydroxyl cations of the various isotopes of Ar, Ne, and He in the Crab Nebula filament and calculate their line emissivity and intrinsic line surface brightness. We successfully explain the observed surface brightness of two transitions of ArH+ (617 and 1234 GHz), one transition of OH+ (971 GHz), and one transition of H2 (2.12 μm). We also explain the observed surface brightness ratios between various molecular and atomic transitions. We find that our model reproduces the overall observed features when a hydrogen number density of ∼(104-106) cm-3 and a cosmic-ray ionization rate per H2 of ∼(10-11-10-10) s-1 are chosen. We discuss the possibility of detecting some hydride and hydroxyl cations in the Crab and diffuse cloud environment. Some transitions of these molecules are highlighted for future astronomical detection
Rapid Accretion State Transitions following the Tidal Disruption Event AT2018fyk
Full text linkFollowing a tidal disruption event (TDE), the accretion rate can evolve from quiescent to near-Eddington levels and back over timescales of months to years. This provides a unique opportunity to study the formation and evolution of the accretion flow around supermassive black holes (SMBHs). We present 2 yr of multiwavelength monitoring observations of the TDE AT2018fyk at X-ray, UV, optical, and radio wavelengths. We identify three distinct accretion states and two state transitions between them. These appear remarkably similar to the behavior of stellar-mass black holes in outburst. The X-ray spectral properties show a transition from a soft (thermal-dominated) to a hard (power-law-dominated) spectral state around Lbol ∼ few × 10−2 LEdd and the strengthening of the corona over time ∼100–200 days after the UV/optical peak. Contemporaneously, the spectral energy distribution (in particular, the UV to X-ray spectral slope αox) shows a pronounced softening as the outburst progresses. The X-ray timing properties also show a marked change, initially dominated by variability at long (>day) timescales, while a high-frequency (∼10−3 Hz) component emerges after the transition into the hard state. At late times (∼500 days after peak), a second accretion state transition occurs, from the hard into the quiescent state, as identified by the sudden collapse of the bolometric (X-ray+UV) emission to levels below 10−3.4 LEdd. Our findings illustrate that TDEs can be used to study the scale (in)variance of accretion processes in individual SMBHs. Consequently, they provide a new avenue to study accretion states over seven orders of magnitude in black hole mass, removing limitations inherent to commonly used ensemble studies
Animations: Turbulence sets the length scale for planetesimal formation:Local 2D simulations of streaming instability and planetesimal formation
No full textThis repository includes three animations discussed in the accepted version of ''Turbulence sets the length scale for planetesimal formation:Local 2D simulations of streaming instability and planetesimal formation" to appear in the Astrophysical Journal.
Short descriptions of the animations are as follows:
Movie 1: Simulations Ae3L0005 and Ae3L0005. Both use \St= 0.1 particles, but only the larger box shows collapse and planetesimal formation. See also: https://youtu.be/gkHiluqH8HY
Movie 2: The evolution of \St= 0.1 pebbles for all 6 different box sizes in Table 1. See also: https://youtu.be/nA87-9_trUc
Movie 3: The evolution of \St= 0.01 pebbles. See also: https://youtu.be/CCywDPKVU8
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
AASJournals/AASTeX60: Version 6.2 official release
No full text<p>This is the official AASTeX Version 6.2 release. It includes</p>
<ul>
<li>a new RNAAS style option for Research Note manuscripts;</li>
<li>Title capitalization changes to match new journal style;</li>
<li>renewal of a command for identifying internal report or preprint numbers;</li>
<li>elimination the page skip between the title page and article body introduced in v6.1;</li>
<li>addition of a widetext environment for text spanning two columns (equations);</li>
<li>an numerous bug fixes.</li>
</ul>This work may be distributed and/or modified under the conditions of the LaTeX Project Public License, either version 1.3c of this license or (at your option) any later version. The latest version of this license is in http://www.latex-project.org/lppl.txt and version 1.3 or later is part of all distributions of LaTeX version 2005/12/01 or later
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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