Search Publications
Multiwavelength identification of millisecond pulsar candidates in the Galactic bulge
Kerr, M.; Calore, F.; Schinzel, F. K. +4 more
Context. The existence of a population of millisecond pulsars in the Galactic bulge is supported, along with other evidence, by the Fermi GeV excess, an anomalous γ-ray emission detected almost 15 years ago in the direction of the Galactic center. However, radio surveys searching for pulsations have not yet revealed bulge millisecond pulsars. Aims…
Unveiling the short and faint X-ray transient nature of IGR J17419–2802
Sidoli, L.; Sguera, V.
We report new X-ray results from the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), Swift, Chandra, and XMM–Newton observations of the hitherto poorly studied unidentified X-ray transient IGR J17419‑2802. We studied in detail the temporal, spectral, and energetic properties of three hard X-ray outbursts detected above 20 keV by INTEGR…
Old massive clusters (and a nuclear star cluster?) in the tidal tails of NGC 5238
Cignoni, M.; Tosi, M.; Bellazzini, M. +12 more
New, deep HST photometry allowed us to identify and study eight compact and bright (MV ≤ ‑5.8) star clusters in the outskirts of the star-forming isolated dwarf galaxy NGC 5238 (M* ≃ 108 M⊙). Five of these clusters are new discoveries, and six appear projected onto and/or aligned with the tidal tails rec…
NGC 1856: Using Machine Learning Techniques to Uncover Detailed Stellar Abundances from MUSE Data
Hernandez, S.; Wang, Z.; Matteucci, F. +5 more
We present the first application of the novel approach based on data-driven machine learning methods applied to Multi-Unit Spectroscopic Explorer (MUSE) field data to derive stellar abundances of star clusters. MUSE has been used to target more than 10,000 fields, and it is unique in its ability to study dense stellar fields such as stellar cluste…
Fractal Effects of the Stellar Medium in the Vicinity of the Sun According to Gaia DR2 Data
Rastorguev, A. S.; Ostashova, M. L.
In this paper, we study the fractal properties of the stellar medium in the solar vicinity based on the Gaia DR2 data for 200 000 stars of all spectral types at distances from 1 to 100 pc from the Sun. We consider the main stages of the development of ideas about the fractal structure in the stellar medium of galaxies. Analysis of the spatial dist…
BST1047+1156: A (Failing) Ultradiffuse Tidal Dwarf in the Leo I Group
Mihos, J. Christopher; Durrell, Patrick R.; McGaugh, Stacy S. +2 more
We use deep Hubble Space Telescope imaging to study the resolved stellar populations in BST1047+1156, a gas-rich, ultradiffuse dwarf galaxy found in the intragroup environment of the Leo I galaxy group. While our imaging reaches approximately two magnitudes below the tip of the red giant branch at the Leo I distance of 11 Mpc, we find no evidence …
Long-Term Variation of the Galactic Cosmic Ray Radiation Dose Rates
Qin, G.; Shen, Z. -N.; Lyu, D.
In this work, a model for calculating the galactic cosmic rays (GCRs) radiation dose rate is developed. The model is based on a GCR modulation model, which is established by Shen and Qin, and the fluence-dose conversion coefficients (FDCCs) published by the International Commission on Radiological Protection (ICRP). With the model, the radiation a…
Study of 26 Galactic Open Clusters with Extended Main-sequence Turnoffs
Li, Zhong-Mu; Deng, Yang-Yang
Recent studies indicate that some Galactic open clusters (OCs) exhibit extended main-sequence turnoff (eMSTO) in their color–magnitude diagrams (CMDs). However, the number of Galactic OCs with eMSTO structures detected so far is limited, and the reasons for their formation are still unclear. This work identifies 26 Galactic OCs with undiscovered e…
A Study of Interstellar Medium in the Line of Sight of Transient Neutron Star Low-Mass X-ray Binary, MXB 1659-298, by Timing and Spectral Analysis
Mahato, Rabindra; Baruah, Monmoyuri; Bhattacharya, Parag
This work is dedicated to the study of interstellar medium (ISM) along the line of sight (LOS) of the transient low-mass X-ray binary, MXB 1659-298, capitalizing the high resolving power of XMM-Newton in the soft energy range. We emphasized the analysis of reflection grating spectrometer (RGS) data in the energy range 0.5–2.15 keV, suitable for th…
Embedded Star Catalog Calculation Tool for Autonomous Star Trackers
Bürger, Karoline C.; Fialho, Fábio de O.; Aykroyd, Christopher R. B.
Autonomous star trackers are crucial attitude sensors for spacecraft three-axis control. They are the most accurate commercial-off-the-shelf sensors available. An autonomous star tracker is an optoelectronic device that autonomously determines the spacecraft's attitude, using an embedded star catalog that is compared to in-orbit images to perform …