Stellar magnetic activity provides substantial information on the magnetic dynamo and the coronal heating process. We present a catalog of X-ray activity for about 6000 stars, based on the Chandra and Gaia DR2 data. We also classified more than 3000 stars as young stellar objects, dwarf stars, or giant stars. By using the stars with valid stellar parameters and classifications, we studied the distribution

We present a CO and atomic fine-structure line-luminosity function analysis using the ALMA Spectroscopic Survey (ASPECS) in the Hubble Ultra Deep Field. ASPECS consists of two spatially overlapping mosaics that cover the entire ALMA 3 mm and 1.2 mm bands. We combine the results of a line-candidate search of the 1.2 mm data cube with those previously obtained from the 3 mm cube. Our analysis shows that

Interstellar ice mantles on the surfaces of dust grains are thought to have a bilayered structure, with a H 2 O-rich polar layer, covered by a CO-rich apolar layer that probably harbors H 2 and other volatiles such as N 2 . In this work, we explore the chemistry induced by 2 keV electrons and Ly α photons in H 2 :CO: 15 N 2 ice analogs of the CO-rich layer when exposed to similar fluences to those

We report molecular gas mass estimates obtained from a stacking analysis of CO line emission in the ALMA Spectroscopic Survey (ASPECS) using the spectroscopic redshifts from the optical integral field spectroscopic survey by the Multi Unit Spectroscopic Explorer (MUSE) of the Hubble Ultra Deep Field (HUDF). Stacking was performed on subsets of the sample of galaxies classified by their stellar mass

Superflares may provide the dominant source of biologically relevant UV radiation to rocky habitable-zone M-dwarf planets (M-Earths), altering planetary atmospheres and conditions for surface life. The combined line and continuum flare emission has usually been approximated by a 9000 K blackbody. If superflares are hotter, then the UV emission may be 10 times higher than predicted from the optical

We examine the absorption-line spectra of a sample of 31 luminous ( ##IMG## [http://ej.iop.org/images/0004-637X/902/2/117/apjabb597ieqn1.gif] {${M}_{\mathrm{UV}}\simeq -23$} ) Lyman break galaxies at redshift z ≃ 6 using data taken with the FOCAS and OSIRIS spectrographs on the Subaru and GTC telescopes. For two of these sources we present longer exposure data taken at higher spectral resolutions from

Here we present the results of an airborne 3–5.4 μ m spectroscopic study of three young, carbon-rich planetary nebulae (PNs) IC 5117, PNG 093.9-00.1, and BD +30 3639. These observations were made using the grism spectroscopy mode of the First Light Infrared TEst CAMera (FLITECAM) instrument during airborne science operations on board NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA).

We make use of sensitive (9.3 μ Jy beam −1 rms) 1.2 mm continuum observations from the Atacama Large Millimeter/submillimeter Array (ALMA) Spectroscopic Survey in the Hubble Ultra-Deep Field (ASPECS) large program to probe dust-enshrouded star formation from 1362 Lyman-break galaxies spanning the redshift range z = 1.5–10 (to ∼7–28 M ⊙ yr −1 at 4 σ over the entire range). We find that the fraction

We investigate the CO excitation and interstellar medium (ISM) conditions in a cold gas mass-selected sample of 22 star-forming galaxies at z = 0.46–3.60, observed as part of the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS). Combined with Very Large Array follow-up observations, we detect a total of 34 CO ##IMG## [http://ej.iop.org/images/0004-637X/902/2/109/apjabb82fieqn1.gif]

We combine the recent determination of the evolution of the cosmic density of molecular gas (H 2 ) using deep, volumetric surveys, with previous estimates of the cosmic density of stellar mass, star formation rate and atomic gas (H i ), to constrain the evolution of baryons associated with galaxies averaged over cosmic time and space. The cosmic H i and H 2 densities are roughly equal at z ∼ 1.5. The

We present an analysis of the structure, kinematics, and orbit of a newly found stellar stream emanating from the globular cluster M92 (NGC 6341). This stream was discovered in an improved matched-filter map of the outer Galaxy, based on a “color–color–magnitude” diagram, created using photometry from the Canada–France Imaging Survey and the Pan-STARRS 1 3 π survey. We find the stream to have a length

We present the last version of HYdrodynamic Ppm Explosion with Radiation diffusION ( Hyperion ), a hydrodynamic code designed to calculate the explosive nucleosynthesis, remnant mass, and light curve associated with the explosion of a massive star. By means of this code, we compute the explosion of a subset of red supergiant models taken from the database published by Limongi & Chieffi for various

Radiative torques (RATs) or mechanical torques acting on irregular grains can induce the alignment of dust grains in respect to the alignment axis (AA), which can be either the direction of the magnetic field or the direction of the radiation. We show that carbonaceous grains can be aligned with their axes both parallel and perpendicular to the AA, and we explore the conditions where the particular

Previous work utilizing NASA’s High-resolution Coronal Imager (Hi-C 2.1) 172 Å observations revealed that, even at the increased spatial scales available in the dataset, there may be evidence for coronal structures that are still not fully resolved. In this follow-up study, cross-section slices of coronal strands are taken across the Hi-C 2.1 field of view. Following previous loop-width studies, the

We report high-quality, H α or CO rotation curves (RCs) to several R e for 41 large, massive, star-forming disk galaxies (SFGs) across the peak of cosmic galaxy evolution ( z ∼ 0.67–2.45), taken with the ESO-VLT, the LBT and IRAM-NOEMA. Most RC41 SFGs have reflection-symmetric RCs plausibly described by equilibrium dynamics. We fit the major axis position–velocity cuts using beam-convolved forward

We present ALMA ∼0.″02 resolution observations of the nucleus of the nearby (∼14 Mpc) type 2 active galactic nucleus NGC 1068 at HCN/HCO + /HNC J = 3–2 lines, as well as at their 13 C isotopologue and vibrationally excited lines, to scrutinize the morphological, dynamical, chemical, and physical properties of dense molecular gas in the putative dusty molecular torus around a mass-accreting supermassive

We propose a theory for the maximum magnitude versus rate of decline (MMRD) relation of novae using free–free emission model light curves built on the optically thick wind theory. We calculated ##IMG## [http://ej.iop.org/images/0004-637X/902/2/91/apjabb5faieqn1.gif] {$({t}_{3},{M}_{V,\max })$} for various sets of ##IMG## [http://ej.iop.org/images/0004-637X/902/2/91/apjabb5faieqn2.gif] {$({\dot{M}}_{\mathrm{acc}}

Cooling white dwarfs (WDs) can yield accurate ages when theoretical cooling models fully account for the physics of the dense plasma of WD interiors. We use MESA to investigate cooling models for a set of massive and ultramassive WDs (0.9–1.3 ##IMG## [http://ej.iop.org/images/0004-637X/902/2/93/apjabb5a5ieqn1.gif] {${M}_{\odot }$} ) for which previous models have failed to match kinematic age indicators

We present the discovery of EVR-CB-004, a close binary with a remnant stellar core and an unseen white dwarf (WD) companion. The analysis in this work reveals that the primary is potentially an inflated hot subdwarf (sdO) and more likely is a rarer post–blue horizontal branch (post-BHB) star. Post-BHBs are the short-lived shell-burning final stage of a blue horizontal star or hot subdwarf before transitioning

The high magnetic field pulsar PSR J1119−6127, detected from radio to high-energy wavelengths, underwent a magnetar-like outburst beginning on 2016 July 27. In this paper, we study the postoutburst multiwavelength properties of this pulsar from the radio to GeV bands and discuss its similarity with the outburst of the magnetar XTE J1810−197. In phase-resolved spectral analysis of 0.5–10 keV X-ray data

Motivated by prior remote observations of a transition from striated solar coronal structures to more isotropic “flocculated” fluctuations, we propose that the dynamics of the inner solar wind just outside the Alfvén critical zone, and in the vicinity of the first ##IMG## [http://ej.iop.org/images/0004-637X/902/2/94/apjabb594ieqn1.gif] {$\beta =1$} surface, is powered by the relative velocities of

Spark gaps are likely the source of plasma in active black hole (BH) magnetospheres. In this paper, we present results of 1D general relativistic particle-in-cell simulations of a starved BH magnetosphere with a realistic treatment of inverse-Compton scattering and pair production, for a broad range of conditions, run times longer than in previous studies, and different setups. We find that following

Optical Fe ii emission is a strong feature in quasar spectra originating in the broad-line region (BLR). The difficulty in understanding the complex Fe ii pseudo-continuum has led us to search for other reliable, simpler ionic species such as Ca ii . In this first part of the series, we confirm the strong correlation between the strengths of two emission features, the optical Fe ii and the NIR Ca ii

The recent discovery of high-redshift ( z > 6) supermassive black holes (SMBH) favors the formation of massive seed BHs in protogalaxies. One possible scenario is the formation of massive stars ##IMG## [http://ej.iop.org/images/0004-637X/902/1/81/apjabb463ieqn1.gif] {$\simeq {10}^{3}\mbox{--}{10}^{4}\,{M}_{\odot }$} via runaway stellar collisions in a dense cluster, leaving behind massive BHs without

Massive, rapidly spinning magnetar remnants produced as a result of binary neutron-star (BNS) mergers may deposit a fraction of their energy into the surrounding kilonova ejecta, powering a synchrotron radio signal from the interaction of the ejecta with the circumburst medium. Here, we present 6.0 GHz Very Large Array (VLA) observations of nine, low-redshift short gamma-ray bursts (GRBs; z < 0.5)

The South Pole Telescope (SPT) has systematically identified 81 high-redshift, strongly gravitationally lensed, dusty star-forming galaxies (DSFGs) in a 2500 square degree cosmological millimeter-wave survey. We present the final spectroscopic redshift survey of this flux-limited ( S 870 μ m > 25 mJy) sample, initially selected at 1.4 mm. The redshift survey was conducted with the Atacama Large Mi

A clear transition feature of galaxy quenching is identified in the multi-parameter space of stellar mass ( M * ), bulge-to-total mass ratio ( B / T m ), halo mass ( M h ) and halo-centric distance ( r / r 180 ). For a given halo mass, the characteristic stellar mass ( ##IMG## [http://ej.iop.org/images/0004-637X/902/1/75/apjabb66cieqn1.gif] {${M}_{* ,\mathrm{ch}}$} ) for the transition is about one-fifth

Stellar winds shape the evolution of stars through the loss of mass. In binary systems, they also shape the stars’ evolution by modifying the orbit. In this paper, we use hydrodynamic simulations to study the emergence of nearly isothermal winds from identical twin binaries. We vary the degree to which model stars fill their Roche lobes and the temperature of the wind. Initialized at rest on the stellar

We present geometric and dynamical modeling of the broad line region (BLR) for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The data set includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the H β , C iv , and Ly α broad emission lines. We find an extended disk-like H β BLR with a mixture of near-circular and outflowing gas

Galaxy morphology and its evolution over the cosmic epoch hold important clues for understanding the regulation of star formation (SF). However, studying the relationship between morphology and SF has been hindered by the availability of consistent data at different redshifts. Our sample, combining CANDELS(0.8 < z < 2.5) and the GALEX-SDSS-WISE Legacy Catalog (GSWLC; z ∼ 0), has physical parameters

We show how the angular clustering between gravitational-wave (GW) standard sirens and galaxies with known redshifts allows an inference of the Hubble constant regardless of whether the host galaxies of any of these sirens are present in the galaxy catalog. We demonstrate this for the first time with realistic simulations of GW signals from binary black holes in a three-detector network with Advanced

Although the interplanetary magnetic-field variability has been extensively investigated in situ using data from several space missions, newly launched missions providing high-resolution measures and approaching the Sun offer the possibility to study the multiscale variability in the innermost solar system. Here, using Parker Solar Probe measurements, we investigate the scaling properties of solar

We present optical, radio, and X-ray observations of SN 2020bvc (=ASASSN-20bs, ZTF 20aalxlis), a nearby ( ##IMG## [http://ej.iop.org/images/0004-637X/902/1/86/apjaba630ieqn1.gif] {$z=0.0252;$} d = 114 Mpc) broad-line (BL) Type Ic supernova (SN) and the first double-peaked Ic-BL discovered without a gamma-ray burst (GRB) trigger. Our observations show that SN 2020bvc shares several properties in common

The joint observation of GW170817 and GRB 170817A indicated that short gamma-ray bursts (SGRBs) can originate from binary neutron star mergers. Moreover, some SGRBs could be detected off axis, while the SGRB jets are highly structured. Then, by assuming a universal angular distribution of the jet emission for all SGRBs, we reproduce the flux and redshift distributions of the cosmological SGRBs detected

We model a compact black hole-accretion disk system in the collapsar scenario with full transport, frequency dependent, general relativistic radiation magnetohydrodynamics. We examine whether or not winds from a collapsar disk can undergo rapid neutron capture (r-process) nucleosynthesis and significantly contribute to solar r-process abundances. We find the inclusion of accurate transport has significant

Starspots are thought to be regions of locally strong magnetic fields, similar to sunspots, and they can generate photometric brightness modulations. To deduce stellar and spot properties, such as spot emergence and decay rates, we implement a computational code for starspot modeling. It is implemented with an adaptive parallel tempering algorithm and an importance sampling algorithm for parameter

The Fe i spectra emitted by astrophysical sources contain information on plasma parameters such as chemical abundances and magnetic fields. However, to determine these parameters requires detailed plasma modeling, which in turn needs accurate atomic data for processes such as radiative decay and electron-impact excitation in Fe i . A lack of fine-structure resolved collision strengths for transitions

Rotation is a significant characteristic of the Sun and other stars, and it plays an important role in understanding their dynamo actions and magnetic activities. In this study, the rotation of the solar chromospheric activity is investigated from a global point of view with an over 40 yr Mg ii index. We determined the time-varying rotational period lengths (RPLs) with the synchrosqueezed wavelet transform

We report the discovery of an ∼6 week quasi-periodic oscillation (QPO) in archival NGC 4945 data observed by the Rossi X-ray Timing Explorer (RXTE) satellite. QPOs are important observables in accretion disks and have been studied extensively in both neutron star (NS) and black hole (BH) X-ray binaries (XRB). QPOs should be present in active galactic nuclei (AGN) if galactic BHs and supermassive black

GW170817 began gravitational-wave multimessenger astronomy. However, GW170817 will not be representative of detections in the coming years because typical gravitational-wave sources will be closer the detection horizon, have larger localization regions, and (when present) will have correspondingly weaker electromagnetic emission. In its design state, the gravitational-wave detector network in the mid-2020s

This paper presents a new approach for the regression of the center coordinates and radius of the solar disk in H α solar full-disk images by using a Deep Convolutional Neural Network. We use ∼100,000 original H α solar full-disk images obtained from Huairou Solar Observing Station as the experimental data set. The data set includes two parts: the original image and three numeric values (center coordinates

We revisit the diagonal ridge feature (diagonal distributions in the R , v ϕ plane) found in Gaia and present a timing analysis for it between Galactocentric distances of R = 7.5 and 12 kpc, using main-sequence turnoff and OB stars selected from the LAMOST Galactic spectroscopic surveys. We recover the ridge pattern in the R – v ϕ plane color coded by mean radial velocity and find that this feature

Residual errors in calibration coefficients corresponding to observed cosmic microwave background (CMB) maps are an important issue when estimating a pure CMB signal. These errors in the input-foreground-contaminated CMB maps, if not properly taken into account in a component separation method, may lead to bias in the cleaned CMB map and estimated CMB angular power spectrum. But the inability to exactly

Massive ( M > 30 M ⊙ ) stars exhibit luminosities that are near the Eddington limit for electron scattering, causing the increase in opacity associated with iron at ##IMG## [http://ej.iop.org/images/0004-637X/902/1/67/apjabb405ieqn1.gif] {$T\,\approx 180,000\,{\rm{K}}$} to trigger supersonic convection in their outer envelopes. Three-dimensional radiative hydrodynamics simulations by Jiang and collaborators

We conduct a rigorous examination of the nearby red supergiant Betelgeuse by drawing on the synthesis of new observational data and three different modeling techniques. Our observational results include the release of new, processed photometric measurements collected with the space-based Solar Mass Ejection Imager instrument prior to Betelgeuse’s recent, unprecedented dimming event. We detect the first

We carry out a comprehensive analysis of supernova SN 2001em covering a period of 19 yr since discovery. SN 2001em is the oldest supernova known to have undergone a metamorphosis from a stripped envelope to an interacting supernova. An early spectrum indicates it exploded as a Type Ib supernova. Later, the ejecta caught up with a dense circumstellar H-shell, ejected a few thousand years before the

We demonstrate a new method for measuring the escape fraction of ionizing photons using Hubble Space Telescope imaging of resolved stars in NGC 4214, a local analog of high-redshift starburst galaxies that are thought to be responsible for cosmic reionization. Specifically, we forward model the UV through near-IR spectral energy distributions of ∼83,000 resolved stars to infer their individual ionizing

We present a reanalysis of the cumulative ACIS-S Chandra data set pointed at the double active galactic nuclei (AGNs) of the NGC 6240 merging galaxy, focusing on the hard energy bands containing the hard spectral continuum (5.5–5.9 keV), the redshifted Fe i K α line (6.0–6.4 keV), and the redshifted Fe xxv line (6.4–6.7 keV). We have used the full Chandra telescope angular resolution and modeled the

We present measurements of [Fe/H] and [ α /Fe] for 128 individual red giant branch stars (RGB) in the stellar halo of M31, including its Giant Stellar Stream (GSS), obtained using spectral synthesis of low- and medium-resolution Keck/DEIMOS spectroscopy ( ##IMG## [http://ej.iop.org/images/0004-637X/902/1/51/apjabb474ieqn1.gif] {$R\sim 3000$} and 6000, respectively). We observed four fields in M31's

The cosmic thermal history, quantified by the evolution of the mean thermal energy density in the universe, is driven by the growth of structures as baryons get shock heated in collapsing dark matter halos. This process can be probed by redshift-dependent amplitudes of the thermal Sunyaev–Zeldovich (SZ) effect background. To do so, we cross-correlate eight sky intensity maps in the Planck and Infrared

The quasar 3C 454.3 is a blazar known for its rapid and violent outbursts seen across the electromagnetic spectrum. Using γ -ray, X-ray, multiband optical, and very-long-baseline interferometric data we investigate the nature of two such events that occurred in 2013 and 2014 accompanied by strong variations in optical polarization, including a ∼230° electric vector position angle (EVPA) rotation. Our

A luminous body embedded in an accretion disk can generate asymmetric density perturbations that lead to a net torque and thus orbital migration of the body. Linear theory has shown that this heating torque gives rise to a migration term linear in the body’s mass that can oppose or even reverse that arising from the sum of gravitational Lindblad and co-orbital torques. We use high-resolution local

N132D is the brightest gamma-ray supernova remnant (SNR) in the Large Magellanic Cloud (LMC). We carried out 12 CO( J = 1–0, 3–2) observations toward the SNR using the Atacama Large Millimeter/submillimeter Array (ALMA) and Atacama Submillimeter Telescope Experiment. We find diffuse CO emission not only at the southern edge of the SNR as previously known, but also inside the X-ray shell. We spatially

Radiative efficiencies of QSOs and their distribution encode rich information on the evolution of both masses and spins of massive black holes (MBHs) across cosmic time. In this paper, we develop a maximum likelihood method to statistically extract the intrinsic relation between radiative efficiency ( ϵ ) and mass ( M • ) of QSOs from their distribution on the luminosity–(empirically estimated virial)

We report the discovery of a new transition type Wolf–Rayet (W-R) WN/C star in the Galaxy. According to its coordinates (R.A., decl.) J2000 = ##IMG## [http://ej.iop.org/images/0004-637X/902/1/62/apjabb0e7ieqn1.gif] {${18}^{{\rm{h}}}{51}^{{\rm{m}}}39\buildrel{\rm{s}}\over{.} 7$} , −05°34′51.″1, and the distance (7.11 ##IMG## [http://ej.iop.org/images/0004-637X/902/1/62/apjabb0e7ieqn2.gif] {${}_{-1.22}^{+1

The early stage of massive galaxy evolution often involves outflows driven by a starburst or a central quasar plus cold mode accretion (infall), which adds to the mass build-up in the galaxies. To study the nature of these infall and outflows in the quasar environments, we have examined the correlation of narrow absorption lines (NALs) at positive and negative velocity shifts to other quasar properties

We present a classification of galaxies in the Pan-STARRS1 (PS1) 3 π survey based on their recent star formation history and morphology. Specifically, we train and test two Random Forest (RF) classifiers using photometric features (colors and moments) from the PS1 data release 2. The labels for the morphological classification are taken from Huertas-Company et al., while labels for the star formation

Electron temperature anisotropies and electron beams are nonthermal features of the observed nonequilibrium electron velocity distributions in the solar wind. In collision-poor plasmas these nonequilibrium distributions are expected to be regulated by kinetic instabilities through wave–particle interactions. This study considers electron instabilities driven by the interplay of core electron temperature

We introduce a generalized form of an emergent dark energy model with one degree of freedom for the dark energy sector that has the flexibility to include both the ΛCDM model as well as the Phenomenologically Emergent Dark Energy (PEDE) model proposed by Li & Shafieloo as two of its special limits. The free parameter for the dark energy sector, namely Δ, has a value of 0 for the Λ case and a value

Redshifts used in current cosmological supernova samples are measured using two primary techniques, one based on well-measured host galaxy spectral lines and the other based on supernova-dominated spectra. Here, we construct an updated Pantheon catalog with revised redshifts, redshift sources, and estimated uncertainties for the entire sample to investigate whether these two techniques yield consistent