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The Astrophysical Journal (ApJ)

Resumen/Descripción – provisto por la editorial en inglés
The Astrophysical Journal is an open access journal devoted to recent developments, discoveries, and theories in astronomy and astrophysics. Publications in ApJ constitute significant new research that is directly relevant to astrophysical applications, whether based on observational results or on theoretical insights or modeling.
Palabras clave – provistas por la editorial

astronomy; astrophysics

Disponibilidad
Institución detectada Período Navegá Descargá Solicitá
No detectada desde jul. 1995 / hasta dic. 2023 IOPScience

Información

Tipo de recurso:

revistas

ISSN impreso

0004-637X

ISSN electrónico

1538-4357

Editor responsable

American Astronomical Society (AAS)

Idiomas de la publicación

  • inglés

País de edición

Reino Unido

Información sobre licencias CC

https://creativecommons.org/licenses/by/4.0/

Cobertura temática

Tabla de contenidos

Photometric Variability of the Pre-main-sequence Stars toward the Sh 2-190 Region

Tirthendu SinhaORCID; Saurabh SharmaORCID; Neelam PanwarORCID; N. Matsunaga; K. Ogura; N. Kobayashi; R. K. YadavORCID; A. GhoshORCID; R. Pandey; P. S. Bisht

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 165

The Poissonian Origin of Power Laws in Solar Flare Waiting Time Distributions

Markus J. AschwandenORCID; Jay R. JohnsonORCID; Yosia I. NurhanORCID

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 166

Three K2 Campaigns Yield Rotation Periods for 1013 Stars in Praesepe

Rayna RampalliORCID; Marcel A. AgüerosORCID; Jason L. CurtisORCID; Stephanie T. DouglasORCID; Alejandro NúñezORCID; Phillip A. CargileORCID; Kevin R. CoveyORCID; Natalie M. GosnellORCID; Adam L. KrausORCID; Nicholas M. LawORCID; Andrew W. MannORCID

<jats:title>Abstract</jats:title> <jats:p>We use three campaigns of K2 observations to complete the census of rotation in low-mass members of the benchmark, ≈670 Myr old open cluster Praesepe. We measure new rotation periods (<jats:italic>P</jats:italic> <jats:sub>rot</jats:sub>) for 220 ≲1.3 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> Praesepe members and recovery periods for 97% (793/812) of the stars with a <jats:italic>P</jats:italic> <jats:sub>rot</jats:sub> in the literature. Of the 19 stars for which we do not recover a <jats:italic>P</jats:italic> <jats:sub>rot</jats:sub>, 17 were not observed by K2. As K2’s three Praesepe campaigns took place over the course of 3 yr, we test the stability of our measured <jats:italic>P</jats:italic> <jats:sub>rot</jats:sub> for stars observed in more than one campaign. We measure <jats:italic>P</jats:italic> <jats:sub>rot</jats:sub> consistent to within 10% for &gt;95% of the 331 likely single stars with ≥2 high-quality observations; the median difference in <jats:italic>P</jats:italic> <jats:sub>rot</jats:sub> is 0.3%, with a standard deviation of 2%. Nearly all of the exceptions are stars with discrepant <jats:italic>P</jats:italic> <jats:sub>rot</jats:sub> measurements in Campaign 18, K2’s last, which was significantly shorter than the earlier two (≈50 days rather than ≈75 days). This suggests that, despite the evident morphological evolution we observe in the light curves of 38% of the stars, <jats:italic>P</jats:italic> <jats:sub>rot</jats:sub> measurements for low-mass stars in Praesepe are stable on timescales of several years. A <jats:italic>P</jats:italic> <jats:sub>rot</jats:sub> can therefore be taken to be representative even if measured only once.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 167

Interstellar Objects Follow the Collapse of Molecular Clouds

Susanne PfalznerORCID; Dylan PatersonORCID; Michele T. BannisterORCID; Simon Portegies Zwart

<jats:title>Abstract</jats:title> <jats:p>Interstellar objects (ISOs), the parent population of 1<jats:sc>i</jats:sc>/‘Oumuamua and 2<jats:sc>i</jats:sc>/Borisov, are abundant in the interstellar medium of the Milky Way. This means that the interstellar medium, including molecular-cloud regions, has three components: gas, dust, and ISOs. From observational constraints of the field density of ISOs drifting in the solar neighborhood, we infer that a typical molecular cloud of 10 pc diameter contains some 10<jats:sup>18</jats:sup> ISOs. At typical sizes ranging from hundreds of meters to tens of kilometers, ISOs are entirely decoupled from the gas dynamics in these molecular clouds. Here we address the question of whether ISOs can follow the collapse of molecular clouds. We perform low-resolution simulations of the collapse of molecular clouds containing initially static ISO populations toward the point where stars form. In this proof-of-principle study, we find that the interstellar objects definitely follow the collapse of the gas—and many become bound to the new-forming numerical approximations to future stars (sinks). At minimum, 40% of all sinks have one or more ISO test particles gravitationally bound to them for the initial ISO distributions tested here. This value corresponds to at least 10<jats:sup>10</jats:sup> actual ISOs being bound after three initial freefall times. Thus, ISOs are a relevant component of star formation. We find that more massive sinks bind disproportionately large fractions of the initial ISO population, implying competitive capture of ISOs. Sinks can also be solitary, as their ISOs can become unbound again—particularly if sinks are ejected from the system. Emerging planetary systems will thus develop in remarkably varied environments, ranging from solitary to richly populated with bound ISOs.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 168

Dust Rings as a Footprint of Planet Formation in a Protoplanetary Disk

Kazuhiro D. KanagawaORCID; Takayuki Muto; Hidekazu TanakaORCID

<jats:title>Abstract</jats:title> <jats:p>Relatively large dust grains (referred to as pebbles) accumulate at the outer edge of the gap induced by a planet in a protoplanetary disk, and a ring structure with a high dust-to-gas ratio can be formed. Such a ring has been thought to be located immediately outside the planetary orbit. We examined the evolution of the dust ring formed by a migrating planet, by performing two-fluid (gas and dust) hydrodynamic simulations. We found that the initial dust ring does not follow the migrating planet and remains at the initial location of the planet in cases with a low viscosity of <jats:italic>α</jats:italic> ∼ 10<jats:sup>−4</jats:sup>. The initial ring is gradually deformed by viscous diffusion, and a new ring is formed in the vicinity of the migrating planet, which develops from the trapping of the dust grains leaking from the initial ring. During this phase, two rings coexist outside the planetary orbit. This phase can continue over ∼1 Myr for a planet migrating from 100 au. After the initial ring disappears, only the later ring remains. This change in the ring morphology can provide clues as to when and where the planet was formed, and is the footprint of the planet. We also carried out simulations with a planet growing in mass. These simulations show more complex asymmetric structures in the dust rings. The observed asymmetric structures in the protoplanetary disks may be related to a migrating and growing planet.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 169

Do Current X-Ray Observations Capture Most of the Black-hole Accretion at High Redshifts?

Guang YangORCID; Vicente Estrada-CarpenterORCID; Casey PapovichORCID; Fabio VitoORCID; Jonelle L. WalshORCID; Zhiyuan Yao; Feng YuanORCID

<jats:title>Abstract</jats:title> <jats:p>The cosmic black hole accretion density (BHAD) is critical for our understanding of the formation and evolution of supermassive black holes (BHs). However, at high redshifts (<jats:italic>z</jats:italic> &gt; 3), X-ray observations report BHADs significantly (∼10 times) lower than those predicted by cosmological simulations. It is therefore paramount to constrain the high-<jats:italic>z</jats:italic> BHAD using independent methods other than direct X-ray detections. The recently established relation between star formation rate and BH accretion rate among bulge-dominated galaxies provides such a chance, as it enables an estimate of the BHAD from the star formation histories (SFHs) of lower-redshift objects. Using the CANDELS Ly<jats:italic>α</jats:italic> Emission At Reionization (CLEAR) survey, we model the SFHs for a sample of 108 bulge-dominated galaxies at <jats:italic>z</jats:italic> = 0.7–1.5, and further estimate the BHAD contributed by their high-<jats:italic>z</jats:italic> progenitors. The predicted BHAD at <jats:italic>z</jats:italic> ≈ 4–5 is consistent with the simulation-predicted values, but higher than the X-ray measurements (by ≈3–10 times at <jats:italic>z</jats:italic> = 4–5). Our result suggests that the current X-ray surveys could be missing many heavily obscured Compton-thick active galactic nuclei (AGNs) at high redshifts. However, this BHAD estimation assumes that the high-<jats:italic>z</jats:italic> progenitors of our <jats:italic>z</jats:italic> = 0.7–1.5 sample remain bulge-dominated where star formation is correlated with BH cold-gas accretion. Alternatively, our prediction could signify a stark decline in the fraction of bulges in high-<jats:italic>z</jats:italic> galaxies (with an associated drop in BH accretion). JWST and Origins will resolve the discrepancy between our predicted BHAD and the X-ray results by constraining Compton-thick AGN and bulge evolution at high redshifts.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 170

Multiple Stellar Populations at Less-evolved Stages-II: No Evidence of Significant Helium Spread among NGC 1846 Dwarfs

Chengyuan LiORCID

<jats:title>Abstract</jats:title> <jats:p>The detection of star-to-star chemical variations in star clusters older than 2 Gyr has changed the traditional view of star clusters as canonical examples of “simple stellar populations” into the so-called “multiple stellar populations” (MPs). Although the significance of MPs seems to correlate with cluster total mass, it seems that the presence of MPs is determined by cluster age. In this article, we use deep photometry from the Hubble Space Telescope to investigate whether the FG-type dwarfs in the ∼1.7 Gyr old cluster NGC 1846, have helium spread. By comparing the observation with the synthetic stellar populations, we estimate a helium spread of Δ<jats:italic>Y</jats:italic> ∼ 0.01 ± 0.01 among the main-sequence stars in NGC 1846. The maximum helium spread would not exceed Δ<jats:italic>Y</jats:italic> ∼ 0.02, depending on the adopted fraction of helium-enriched stars. To mask the color variation caused by such a helium enrichment, a nitrogen enrichment of at least Δ[N/Fe] = 0.8 dex is required, which is excluded by previous analyses of the red-giant branch in this cluster. We find that our result is consistent with the Δ<jats:italic>Y</jats:italic>–mass relationship for Galactic globular clusters. To examine whether or not NGC 1846 harbors MPs, higher photometric accuracy is required. We conclude that under the adopted photometric quality, there is no extreme helium variation among NGC 1846 dwarfs.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 171

Confined and Eruptive Catastrophes of Solar Magnetic Flux Ropes Caused by Mass Loading and Unloading

Quanhao ZhangORCID; Rui LiuORCID; Yuming WangORCID; Xiaolei Li; Shaoyu LyuORCID

<jats:title>Abstract</jats:title> <jats:p>It is widely accepted that coronal magnetic flux ropes are the core structures of large-scale solar eruptive activities, which have a dramatic impact on the solar-terrestrial system. Previous studies have demonstrated that varying magnetic properties of a coronal flux rope system could result in a catastrophe of the rope, which may trigger solar eruptive activities. Since the total mass of a flux rope also plays an important role in stabilizing the rope, we use 2.5 dimensional magnetohydrodynamic numerical simulations in this article to investigate how a flux rope evolves as its total mass varies. It is found that an unloading process that decreases the total mass of the rope could result in an upward (eruptive) catastrophe in the flux rope system, during which the rope jumps upward and the magnetic energy is released. This indicates that mass unloading processes could initiate the eruption of the flux rope. Moreover, when the system is not too diffusive, there is also a downward (confined) catastrophe that could be caused by mass loading processes via which the total mass accumulates. The magnetic energy, however, is increased during the downward catastrophe, indicating that mass loading processes could cause confined activities that may contribute to the storage of energy before the onset of coronal eruptions.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 172

The Water-ice Feature in Near-infrared Disk-scattered Light around HD 142527: Micron-sized Icy Grains Lifted up to the Disk Surface?

Ryo TazakiORCID; Koji MurakawaORCID; Takayuki Muto; Mitsuhiko HondaORCID; Akio K. InoueORCID

<jats:title>Abstract</jats:title> <jats:p>We study the 3 <jats:italic>μ</jats:italic>m scattering feature of water ice detected in the outer disk of HD 142527 by performing radiative transfer simulations. We show that an ice mass abundance at the outer disk surface of HD 142527 is much lower than estimated in a previous study. It is even lower than inferred from far-infrared ice observations, implying ice disruption at the disk surface. Next, we demonstrate that a polarization fraction of disk-scattered light varies across the ice-band wavelengths depending on ice grain properties; hence, polarimetric spectra would be another tool for characterizing water-ice properties. Finally, we argue that the observed reddish disk-scattered light is due to grains a few microns in size. To explain the presence of such grains at the disk surface, we need a mechanism that can efficiently oppose dust settling. If we assume turbulent mixing, our estimate requires <jats:italic>α</jats:italic> ≳ 2 × 10<jats:sup>−3</jats:sup>, where <jats:italic>α</jats:italic> is a nondimensional parameter describing the vertical diffusion coefficient of grains. Future observations probing gas kinematics would be helpful to elucidate vertical grain dynamics in the outer disk of HD 142527.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 173

Radiative-dynamical Simulation of Jupiter’s Stratosphere and Upper Troposphere

Nicholas G. ZubeORCID; Xi Zhang; Tao LiORCID; Tianhao LeORCID; Cheng LiORCID; Sandrine GuerletORCID; Xianyu TanORCID

<jats:title>Abstract</jats:title> <jats:p>We present a two-dimensional radiative-dynamical model of the combined stratosphere and upper troposphere of Jupiter to understand its temperature distribution and meridional circulation pattern. Our study highlights the importance of radiative and mechanical forcing for driving the middle atmospheric circulation on Jupiter. Our model adopts a state-of-the-art radiative transfer scheme with recent observations of Jovian gas abundances and haze distribution. Assuming local radiative equilibrium, latitudinal variation of hydrocarbon abundances is not able to explain the observed latitudinal temperature variations in the mid-latitudes. With mechanical forcing parameterized as a frictional drag on zonal wind, our model produces ∼2 K latitudinal temperature variations observed in low to mid-latitudes in the troposphere and lower stratosphere, but cannot reproduce the observed 5 K temperature variations in the middle stratosphere. In the high latitudes, temperature and meridional circulation depend strongly on polar haze radiation. The simulated residual mean circulation shows either two broad equator-to-pole cells or multi-cell patterns, depending on the frictional drag timescale and polar haze properties. A more realistic wave parameterization and a better observational characterization of haze distribution and optical properties are needed to better understand latitudinal temperature distributions and circulation patterns in the middle atmosphere of Jupiter.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 174