Search Results - "Stars"

We present the first NuSTAR X-ray observation of EF Eri, a well-known polar system. The NuSTAR observation was conducted in conjunction with NICER shortly after EF Eri entered a high accretion state following an unprecedented period of low activity lasting 26 yr since 1997. NuSTAR detected hard X-ra...

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We present a catalog of 652 young stellar objects (YSOs) in the Carina star-forming region. The catalog was constructed by combining near-infrared K _S -band variability from the VISTA Variables in the Vía Láctea eXtended survey and medium-resolution H -band spectroscopy from APOGEE-2, Sloan Digital...

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This paper presents a review of the main properties of ultra-long-period Cepheids (ULPs). The analysis is based on the largest sample of known ULPs, comprising 73 pulsators, including the first ULP discovered in the Milky Way. These intrinsically highly luminous variables can be observed at distance...

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While massive stars are known to shape galactic ecosystems, their formation has long been assumed to require the high-density environments of inner galactic disks. This paradigm is challenged by mounting evidence of young massive stars in extended galaxy outskirts, yet direct confirmation of in situ...

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Stellar systems consisting of three or more stars are not an uncommon occurrence in the Galaxy. Nearly 50% of solar-type wide binaries with separations >1000 au are actually higher-order multiples with one component being a close binary. Additionally, the higher-order multiplicity fraction appear...

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We conducted a timing analysis of PSR J0922+0638 (B0919+06) using data from the Nanshan 26 m radio telescope and the MeerKAT telescope, spanning from 2001 January to 2023 March. During this 22 yr period, we discovered a previously unreported small glitch (glitch 1) before the well-known large glitch...

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A photometric investigation of six binary systems of the W Ursae Majoris (W UMa)-type is presented. We extracted primary and secondary minima from the Transiting Exoplanet Survey Satellite observations of these systems. Using observations previously reported in the literature, linear fits in the O –...

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The detection and characterization of periodic X-ray signals are crucial for identifying new compact objects and studying the mechanisms powering their emission. We report on the timing and spectral variability of CXOU J204734.8+300105, a proposed eclipsing polar-type cataclysmic variable (CV) candi...

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The Asymptotic Giant Branch (AGB) is the late stage of the evolution of intermediate and low-mass stars and is of great importance for understanding stellar evolution, nucleosynthesis, and the chemical evolution of galaxies. This paper systematically reviews the methods for identifying AGB stars, fr...

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We present the radio continuum counterparts to the enigmatic ultracompact X-ray binaries (UCXBs): a black hole or neutron star accreting from a hydrogen-deficient white dwarf donor star with short orbital periods (<80 minutes). For the sample of UCXBs hosted by globular clusters (GCs), we search...

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Recent analyses on the properties of the central compact object in the HESS J1731-347 remnant and the PSR J1231-1411 pulsar indicated that these two compact objects are characterized by similar (low) masses and possibly different radii. This paper aims at reconciling the aforementioned measurements...

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Transitional millisecond pulsars (tMSPs) bridge the evolutionary gap between accreting neutron stars in low-mass X-ray binaries and millisecond radio pulsars. These systems exhibit a unique subluminous X-ray state characterized by the presence of an accretion disk and rapid switches between high and...

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Using Keck DEIMOS spectra of stars in the Andromeda (M31) and Triangulum (M33) galaxies, selected from the large multiband (near-ultraviolet, visible light, and near-infrared) Hubble Space Telescope surveys PHAT and PHATTER, respectively, we have identified a subset of stars that contain a previousl...

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In this study, we present refined orbital and fundamental parameters of the Galactic B[e] supergiant binary system HD 327083 using the Bayesian Markov Chain Monte Carlo (MCMC) method applied to the radial velocities data of HD 327083. We found that the system is well described by a circular orbital...

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Long-lasting episodes of high accretion can strongly impact stellar and planetary formation. However, the universality of these events during the formation of young stellar objects (YSOs) is still under debate. Accurate statistics of strong outbursts (FUors) are necessary to understand the role of e...

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Several phenomenological aspects of low-luminosity neutron star transients, such as atolls, remain poorly understood. One such source, MAXI J1807+132, entered its latest outburst in 2023 July. To thoroughly characterize this outburst, we conducted an extensive observational campaign spanning radio t...

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We report discoveries of bow-shock nebulae, seen in H α and [O iii ] λ 5007, around two cataclysmic variables (CVs): LS Pegasi and ASASSN-V J205457.73+515731.9 (ASASJ2054). Additionally, both stars lie near the edges of faint extended H α -emitting nebulae. The orientations of the bow shocks are con...

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