adsabs/SciX_UAT_keywords huggingface dataset:
Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc

We explore the impact of outer stellar companions on the occurrence rate of giant planets detected with radial velocities. We searched for stellar and planetary companions to a volume-limited sample of solar-type stars within 25 pc. Using adaptive optics imaging observations from the Lick 3 m and Palomar 200″ Telescopes, we characterized the multiplicity of our sample stars, down to the bottom of the main sequence. With these data, we confirm field star multiplicity statistics from previous surveys. We additionally combined three decades of radial velocity (RV) data from the California Planet Search with newly collected RV data from Keck/HIRES and the Automated Planet Finder/Levy Spectrometer to search for planetary companions in these same systems. Using an updated catalog of both stellar and planetary companions, as well as detailed injection/recovery tests to determine our sensitivity and completeness, we measured the occurrence rate of planets among the single- and multiple-star systems. We found that planets with masses in the range of 0.1-10 MJ and with semimajor axes of 0.1-10 au have an occurrence rate of ${0.18}_{-0.03}^{+0.04}$ planets per star when they orbit single stars and an occurrence rate of 0.12 ± 0.04 planets per star when they orbit a star in a binary system. Breaking the sample down by the binary separation, we found that only one planet-hosting binary system had a binary separation <100 au, and none had a separation <50 au. These numbers yielded planet occurrence rates of ${0.20}_{-0.06}^{+0.07}$ planets per star for binaries with separation aB > 100 au and ${0.04}_{-0.02}^{+0.04}$ planets per star for binaries with separation aB < 100 au. The similarity in the planet occurrence rate around single stars and wide primaries implies that wide binary systems should actually host more planets than single-star systems, since they have more potential host stars. We estimated a system-wide planet occurrence rate of 0.3 planets per wide binary system for binaries with separations aB > 100 au. Finally, we found evidence that giant planets in binary systems have a different semimajor-axis distribution than their counterparts in single-star systems. The planets in the single-star sample had a significantly higher occurrence rate outside of 1 au than inside 1 au by nearly 4σ, in line with expectations that giant planets are most common near the snow line. However, the planets in the wide binary systems did not follow this distribution, but rather had equivalent occurrence rates interior and exterior to 1 au. This may point to binary-mediated planet migration acting on our sample, even in binaries wider than 100 au.

Keywords: radial velocity; exoplanet catalogs; exoplanet formation; planet hosting stars
The Goldstone Apple Valley Radio Telescope (GAVRT) Search for Extra Terrestrial Intelligence (SETI)

This paper reports the results from a student-led Search for Extraterrestrial Intelligence (SETI), also known as technosignatures, targeting the plane of the Milky Way as a part of the Goldstone Apple Valley Radio Telescope (GAVRT) collaboration between the Lewis Center for Educational Research (LCER) and the Jet Propulsion Laboratory. Students associated with LCER submit analytic reports of spectral data targeting specific regions of the Milky Way, identifying interference, noise, and Candidate signals potentially originating from intelligent sources. GAVRT-SETI's search is guided by the assumption that a narrow-band radio signal (<1.5 Hz) from a fixed location in the sky, occurring across multiple observation periods, is unlikely to be caused by instrument noise or by a natural source. Thus, we searched the reported data for similar signals occurring during different observation periods within the same region of sky. No such signals were found. However, our analysis of the frequency distribution of Candidates suggests that at least a few percent of the Candidates are associated with low-level radio-frequency interference.

Keywords: technosignatures; radio astronomy
Using the Optical-NIR Spectral Energy Distributions to Search for the Evidence of Dust Formation of 66 Supernovae

In this paper, we searched for the dust formation evidence of 66 supernovae (SNe) by using the blackbody model and the blackbody plus dust emission model to fit their early-time optical-near-infrared (NIR) spectral energy distributions (SEDs). We find that, while the blackbody model can fit most SEDs of the SNe in our sample, the model cannot fit the SEDs of some SNe in which the SEDs of two SNe (SNe 2010bq and 2012ca) show NIR excesses which can be attributed to the emission from the heated dust. We use the blackbody plus dust emission model to fit the SEDs showing NIR excesses, finding that both the graphite and silicate dust models can fit the SEDs, and the graphite model gets reasonable temperatures or better fits. Assuming that the dust is graphite, the best-fitting temperatures (masses) of the dust of SNe 2010bq and 2012ca are ~1300-1800 K (~0.1-3.4 ×10-4 M ⊙) and ~600-1000 K (~0.6-7.5 × 10-3 M ⊙), respectively. We compare the vaporization radii and the blackbody radii of the dust shells of the two SNe with the upper limits of the ejecta radii of the SNe at the first epochs, and demonstrate that the NIR excesses of the SEDs of the two SNe might be caused by the pre-existing dust.

Keywords: circumstellar dust
The Curious Case of Twin Fast Radio Bursts: Evidence for Neutron Star Origin?

Fast radio bursts (FRBs) are brilliant short-duration flashes of radio emission originating at cosmological distances. The vast diversity in the properties of currently known FRBs and the fleeting nature of these events make it difficult to understand their progenitors and emission mechanism(s). Here we report high time resolution polarization properties of FRB 20210912A, a highly energetic event detected by the Australian Square Kilometre Array Pathfinder (ASKAP) in the Commensal Real-time ASKAP Fast Transients survey, which show intraburst position angle (PA) variation similar to Galactic pulsars and unusual variation of Faraday rotation measure (RM) across its two sub-bursts. The observed intraburst PA variation and apparent RM variation pattern in FRB 20210912A may be explained by a rapidly spinning neutron star origin, with rest-frame spin periods of ∼1.1 ms. This rotation timescale is comparable to the shortest known rotation period of a pulsar and close to the shortest possible rotation period of a neutron star. Curiously, FRB 20210912A exhibits a remarkable resemblance to the previously reported FRB 20181112A, including similar rest-frame emission timescales and polarization profiles. These observations suggest that these two FRBs may have similar origins.

Keywords: time domain astronomy; radio transient sources; radio bursts
Discovery of a 584.65 Hz Burst Oscillation in the Low-mass X-Ray Binary 4U 1730-22

Type-I X-ray burst oscillations are powered by thermonuclear energy released on the neutron star (NS) surface in low-mass X-ray binaries (LMXBs), where the burst oscillation frequencies are close to the NS spin rates. In this work, we report the detection of oscillation at 584.65 Hz during the cooling tail of type-I X-ray bursts observed from the accreting NS LMXB 4U 1730-22 on 2022 March 20, by the Neutron star Interior Composition Explorer telescope. The oscillation signal showed a strong Leahy power, P m ~ 54.04, around 584.65 Hz, which has single-trial and multiple-trial confidence levels of 7.05σ and 4.73σ, respectively. The folded pulse profile of the oscillation in the 0.2-10 keV band showed a sinusoidal shape with the fractional rms amplitude of (8.0 ± 1.1)%. We found the oscillation frequency showed insignificant upward drifting, i.e., less than 0.3 Hz, during the cooling tail, similar to the behavior appearing in accreting millisecond X-ray pulsars (AMXP), and indicate the source could be an AMXP spinning at 1.71 ms.

Keywords: x-ray bursts; neutron stars; low-mass x-ray binary stars; x-ray sources
Close Companions to the T Tauri Stars CVSO 109 and CVSO 165 Observed by the HST ULLYSES Program

The Hubble Space Telescope (HST) Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) program is a HST Director's Discretionary program that is in the process of obtaining a large library of ultraviolet spectroscopic observations of young stars of both high and low masses. We present information on close companions to the T Tauri stars CVSO 109 and CVSO 165 in Orion that were observed with the HST as part of this program. CVSO 109 has a fainter companion at an angular separation ρ = 0"64 near PA = 218° and Δ(F28X50LP) ≈ 0.6 mag, while the CVSO 165 companion is at ρ = 0"30 near PA = 326° with Δ(F28X50LP) ≈ 1.7 mag. Both components of CVSO 165 appear to be active stars with strong emission features, while the CVSO 109 companion shows only modest indications of stellar activity. Extracted spectra for each of these components will be included in ULLYSES Data Release 2.

Keywords: t tauri stars; binary stars; companion stars
Surveys of Clumps, Cores, and Condensations in Cygnus X. II. Radio Properties of Massive Dense Cores

We have carried out a high-sensitivity and high-resolution radio continuum study toward a sample of 47 massive dense cores (MDCs) in the Cygnus X star-forming complex using the Karl G. Jansky Very Large Array, aiming to detect and characterize the radio emission associated with star-forming activities down to ~0.01 pc scales. We have detected 64 radio sources within or closely around the FWHMs of the MDCs, of which 37 are reported for the first time. The majority of the detected radio sources are associated with dust condensations embedded within the MDCs, and they are mostly weak and compact. We are able to build spectral energy distributions for eight sources. Two of them indicate nonthermal emission and the other six indicate thermal free-free emission. We have determined that most of the radio sources are ionized jets or winds originating from massive young stellar objects, whereas only a few sources are likely to be ultracompact H II regions. Further quantitative analyses indicate that the radio luminosity of the detected radio sources increases along the evolution path of the MDCs.

Keywords: radio jets; protostars; star formation; h ii regions
Elemental Abundances in M31: Individual and Coadded Spectroscopic [Fe/H] and [α/Fe] throughout the M31 Halo with SPLASH

We present spectroscopic chemical abundances of red giant branch stars in Andromeda (M31), using medium-resolution (R ~ 6000) spectra obtained via the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. In addition to individual chemical abundances, we coadd low signal-to-noise ratio spectra of stars to obtain a high enough signal to measure average [Fe/H] and [α/Fe] abundances. We obtain individual and coadded measurements for [Fe/H] and [α/Fe] for M31 halo stars, covering a range of 9-180 kpc in projected radius from the center of M31. With these measurements, we greatly increase the number of outer halo (R proj > 50 kpc) M31 stars with spectroscopic [Fe/H] and [α/Fe], adding abundance measurements for 45 individual stars and 33 coadds from a pool of an additional 174 stars. We measure the spectroscopic metallicity ([Fe/H]) gradient, finding a negative radial gradient of -0.0084 ± 0.0008 for all stars in the halo, consistent with gradient measurements obtained using photometric metallicities. Using the first measurements of [α/Fe] for M31 halo stars covering a large range of projected radii, we find a positive gradient (+0.0027 ± 0.0005) in [α/Fe] as a function of projected radius. We also explore the distribution in [Fe/H]-[α/Fe] space as a function of projected radius for both individual and coadded measurements in the smooth halo, and compare these measurements to those stars potentially associated with substructure. These spectroscopic abundance distributions add to existing evidence that M31 has had an appreciably different formation and merger history compared to our own Galaxy.

Keywords: stellar abundances; stellar streams; galaxy stellar halos; andromeda galaxy; local group
Photoionization Models for High-density Gas

Relativistically broadened and redshifted 6.4-6.9 keV iron K lines are observed from many accretion powered objects, including X-ray binaries and active galactic nuclei. The existence of gas close to the central engine implies large radiation intensities and correspondingly large gas densities if the gas is to remain partially ionized. Simple estimates indicate that high gas densities are needed to allow for the survival of iron against ionization. These are high enough that rates for many atomic processes are affected by mechanisms related to interactions with nearby ions and electrons. Radiation intensities are high enough that stimulated processes can be important. Most models currently in use for interpreting relativistic lines use atomic rate coefficients designed for use at low densities and neglect stimulated processes. In our work so far we have presented atomic structure calculations with the goal of providing physically appropriate models at densities consistent with line-emitting gas near compact objects. In this paper we apply these rates to photoionization calculations, and produce ionization balance curves and X-ray emissivities and opacities that are appropriate for high densities and high radiation intensities. The final step in our program will be presented in a subsequent paper in which model atmosphere calculations will incorporate these rates into synthetic spectra.

Keywords: x-ray astronomy; atomic physics; x-ray observatories; atomic spectroscopy
Hubble Space Telescope Observations of Tadpole Galaxies Kiso3867, SBS0, SBS1, and UM461

Tadpole galaxies are metal-poor dwarfs with typically one dominant star-forming region, giving them a head-tail structure when inclined. A metallicity drop in the head suggests that gas accretion with even lower metallicity stimulated the star formation. Here we present multiband Hubble Space Telescope WFC3 and Advanced Camera for Surveys images of four nearby (<25 Mpc) tadpoles, SBS0, SBS1, Kiso3867, and UM461, selected for their clear metallicity drops shown in previous spectroscopic studies. The properties of the star complexes and compact clusters are measured. Each galaxy contains from three to 10 young stellar complexes with 103-105 M ⊙ of stars ~3-10 Myr old. Between the complexes, the disk has a typical age of ~3 Gyr. Numerous star clusters cover the galaxies, both inside and outside the complexes. The combined cluster mass function, made by normalizing the masses and counts before stacking, is a power law with a slope of -1.12 ± 0.14 on a log-log plot and the combined distribution function of cluster lifetime decays with age as t -0.65±0.24. A comparison between the summed theoretical Lyman continuum (LyC) emission from all the clusters, given their masses and ages, is comparable to or exceeds the LyC needed to excite the observed Hα in some galaxies, suggesting LyC absorption by dust or undetected gas in the halo, or perhaps galaxy escape.

Keywords: blue compact dwarf galaxies; star forming regions; young star clusters
No Massive Companion to the Coherent Radio-emitting M Dwarf GJ 1151

The recent detection of circularly polarized, long-duration (>8 hr), low-frequency (∼150 MHz) radio emission from the M4.5 dwarf GJ 1151 has been interpreted as arising from a star-planet interaction via the electron cyclotron maser instability. The existence or parameters of the proposed planets have not been determined. Using 20 new HARPS-N observations, we put 99th-percentile upper limits on the mass of any close companion to GJ 1151 at $M\sin I\lt 5.6\,{M}_{\oplus }$ . With no stellar, brown dwarf, or giant planet companion likely in a close orbit, our data are consistent with detected radio emission emerging from a magnetic interaction between a short-period terrestrial-mass planet and GJ 1151 (https://github.com/benjaminpope/video).

Keywords: magnetic fields; radial velocity; solar-planetary interactions
A Zwicky Transient Facility Look at Optical Variability of Young Stellar Objects in the North America and Pelican Nebulae Complex

We present a study of 323 photometrically variable young stellar objects that are likely members of the North America and Pelican nebulae star-forming region. To do so, we utilize over two years of data in the g and r photometric bands from the Zwicky Transient Facility. We first investigate periodic variability, finding 46 objects (~15% of the sample) with significant periods that phase well and can be attributed to stellar rotation. We then use the quasiperiodicity (Q) and flux asymmetry (M) variability metrics to assign morphological classifications to the remaining aperiodic light curves. Another ~39% of the variable star sample beyond the periodic (low Q) sources are also flux-symmetric, but with a quasiperiodic (moderate Q) or stochastic (high Q) nature. Concerning flux-asymmetric sources, our analysis reveals ~14% bursters (high negative M) and ~29% dippers (high positive M). We also investigate the relationship between variability slopes in the g versus g - r color-magnitude diagram, and the light-curve morphological classes. Burster-type objects have shallow slopes, while dipper-type variables tend to have higher slopes that are consistent with extinction-driven variability. Our work is one of the earliest applications of the Q and M metrics to ground-based data. We therefore contrast the Q values of high-cadence and high-precision space-based data, for which these metrics were designed, with Q determinations resulting from degraded space-based light curves that have the cadence and photometric precision characteristic of ground-based data.

Keywords: young star clusters; pre-main sequence stars; t tauri stars; slow irregular variable stars; stellar rotation; time domain astronomy
Hemispheric Sunspot Number from the Madrid Astronomical Observatory for the Period 1935-1986

Long-term studies on hemispheric asymmetry can help to understand better the solar dynamo. We present the hemispheric sunspot number calculated from daily sunspot observations made at the Madrid Astronomical Observatory for the period 1935-1986 (corresponding approximately to Solar Cycles 17-21). From this data set, we also analyzed the asymmetry index and hemispheric phase shifts. We conclude that the northern hemisphere was predominant in Solar Cycles 17-20, whereas the southern hemisphere was predominant in Solar cycle 21. The strongest asymmetries are found in Solar Cycles 20 (with a relative difference between both hemispheres of 44%) and 19 (39%). A normalization of the Madrid hemispheric sunspot number was also made with respect to the sunspot number (Version 2). Our results agree with previous studies on hemispheric asymmetry around the mid-20th century and their secular trends.

Keywords: solar cycle; the sun; sunspot number
The Dynamics, Destruction, and Survival of Supernova-formed Dust Grains

Observations have demonstrated that supernovae efficiently produce dust. This is consistent with the hypothesis that supernovae and asymptotic giant branch stars are the primary producers of dust in the universe. However, there has been a longstanding question of how much of the dust detected in the interiors of young supernova remnants can escape into the interstellar medium. We present new hydrodynamical calculations of the evolution of dust grains that were formed in dense ejecta clumps within a Cas A-like remnant. We follow the dynamics of the grains as they decouple from the gas after their clump is hit by the reverse shock. They are subsequently subject to destruction by thermal and kinetic sputtering as they traverse the remnant. Grains that are large enough (∼0.25 μm for silicates and ∼0.1 μm for carbonaceous grains) escape into the interstellar medium while smaller grains get trapped and destroyed. However, grains that reach the interstellar medium still have high velocities, and are subject to further destruction as they are slowed down. We find that for initial grain size distributions that include large (∼0.25-0.5 μm) grains, 10%-20% of silicate grains can survive, while 30-50% of carbonaceous grains survive even when the initial size distribution cuts off at smaller (0.25 μm) sizes. For a 19 M⊙ star similar to the progenitor of Cas A, up to 0.1 M⊙ of dust can survive if the dust grains formed are large. Thus we show that supernovae under the right conditions can be significant sources of interstellar dust.

Keywords: interstellar dust; interstellar dust processes; supernova remnants; core-collapse supernovae
Pair Separation in Parallel Electric Field in Magnetar Magnetosphere and Narrow Spectra of Fast Radio Bursts

When the magnetosphere of a magnetar is perturbed by crustal deformation, an electric field E∥ parallel to the magnetic field line would appear via Alfvén waves in the charge starvation region. The electron-positron pair bunches will be generated via two-stream instability in the magnetosphere, and these pairs will undergo charge separation in the E∥ and in the meantime emit coherent curvature radiation. Following the approach of Yang & Zhang, we find that the superposed curvature radiation becomes narrower due to charge separation, with the width of spectrum depending on the separation between the electron and positron clumps. This mechanism can interpret the narrow spectra of fast radio bursts (FRBs), in particular, the spectrum of Galactic FRB 200428 recently detected in association with a hard X-ray burst from the Galactic magnetar SGR J1935+2154.

Keywords: radio transient sources; galactic radio sources; radio bursts; magnetars
Robustness of the Pairwise Kinematic Sunyaev-Zeldovich Power Spectrum Shape as a Cosmological Gravity Probe

We prove from the modified gravity (MG) galaxy/halo mock catalogs that the shape of the pairwise kinematic Sunyaev-Zeldovich (kSZ) power spectrum PkSZ has constraining power on discriminating different gravity theories on cosmological scales. By varying the effective optical depth τT as a free parameter, we verify that the τT-f (the linear growth rate) degeneracy in the linear theory of PkSZ is broken down by the nonlinear structure growth and the scale dependence of f in some MG theories. Equivalently speaking, the shape of PkSZ alone could be used to tightly constrain the MG theories on cosmological scales. With good knowledge of galaxy density biases, we verify that a combination of the next-generation galaxy spectroscopic redshift and CMB surveys, e.g., BOSS+CMB-S4 or DESI+CMB-S4, could potentially discriminate f(R) models from the general relativity at the ∼5σ level using the shape of the galaxy pairwise kSZ dipole PkSZ,ℓ = 1 alone, when fR0 = 10-4.

Keywords: dark energy; dark matter; cosmological parameters from large-scale structure; sunyaev-zeldovich effect