arXiv subjects

A. Yeghikyan

Publications and source records attributed to A. Yeghikyan.

4 recordsLinked to original sources

arXiv2026

Dust and Ices in the SNR

The presence of dust in supernova remnants (SNRs) is confirmed by extensive infrared data from observatories such as Spitzer, Herschel, and JWST, alongside theoretical models of dust formation. This study explores the existence of dust and ices, particularly water ice via 62 μm in SNRs such as the Crab Nebula and N49, using observational data and preliminary modeling with Cloudy. Observations suggest that water ice may be present in IC 443 and possibly other remnants, though the 63 μm band could also indicate [OI] emission. Theoretical models indicate that water ice could survive under certain conditions in SNRs, with densities and temperatures analyzed. Further observations and refined simulations are needed to confirm these findings.

astro-ph.HE↗

arXiv2026

Dynamical Preconditions for Ice Formation in Supernova Remnant and Cloud Interactions: A 2D MHD Study

Water ice has been detected in several supernova remnants despite the strong heating and radiation in these environments. This challenges standard expectations for dust survival. Using two dimensional magnetohydrodynamic simulations, we study how a supernova shock interacts with a dense interstellar cloud. The simulations show that the shock naturally compresses the cloud into dense structures similar to those inferred in well known remnants. Although temperatures remain high in the adiabatic phase, simple considerations indicate that cooling would act quickly once included. These results suggest that shock cloud interactions create the physical conditions needed for water ice to form. Future work including radiative cooling and grain surface chemistry will allow direct modelling of ice growth in these compressed regions.

astro-ph.HE↗

arXiv2025

IdentYS: A Python-Based Tool for Identifying Young Stars in Star-Forming Regions

Research on young stellar populations is essential to understand the properties of embedded clusters and advance theories of their formation. This has driven advancements in methodologies for star detection, leading to the development of valuable databases and software. We present the scientific justification and operating principles of the IdentYS tool, which is designed to identify young stellar objects (YSOs) in star-forming regions. The tool facilitates the identification of young stars with infrared (IR) excess in remote and embedded star-forming regions, focusing primarily on Class I and II YSOs. For this purpose, near- and mid-IR photometric data and five colour-colour diagrams (J - H) vs. (H - K), K - [3.6] vs. [3.6] - [4.5], [3.6] - [4.5] vs. [5.8] - [8.0], [3.6] - [4.5] vs. [8.0] - [24], and [3.4] - [4.6] vs. [4.6] - [12] are used. The purity of the YSOs sample is enhanced by excluding field contamination from stellar and extragalactic objects. As a result, we compile a list of YSO candidates displaying the source designation, astrometric, and photometric parameters, as well as information on the evolutionary stage determined by the presence of IR excess, as indicated by certain diagrams. The application of this program can greatly streamline the statistical analysis of young stellar populations across diverse star-forming regions, including distant and deeply embedded ones, which typically require processing large volumes of initial data.

astro-ph.SR↗

arXiv2024

Searching for stellar population in the molecular cloud GRSMC 045.49+00.04

Understanding the characteristics of young stellar populations is essential for deriving insights into star formation processes within parent molecular clouds and the influence of massive stars. This study focuses on YSOs in the G 045.49+00.04 molecular cloud, including three UC HII regions. Using infrared photometric data and radiation models, we identified 1482 YSOs with masses ranging from 1.5 to 22 Msol. Among these, 315 form dense clusters near IRAS sources, with high-mass stars responsible for ionization. The non-cluster YSOs (1168) are uniformly distributed on the field. The distribution of YSOs from both samples on the colour-magnitude diagram and by the evolutionary ages is different. About 75% of objects in the IRAS clusters are concentrated around the ZAMS and have a well-defined peak at an age of Log(Age[years]) = 6.75, with a narrow spread. The non-cluster objects have two concentrations located to the right and left of the 0.1 Myr isochrone and two well-defined peaks at Log(Age) = 6.25 and 5.25. The K luminosity functions alpha slopes for the IRAS clusters and non-cluster objects are 0.32 and 0.72, respectively. The steeper alpha slope is suggesting that the non-cluster objects are less evolved, which is well consistent with the evolutionary age. Similar patterns were observed in the neighboring G 45.14+00.14 region. The both regions (G 045.49+00.04 and G 45.14+00.14) are located and distinguished by their brightness and density at the edge of the bubble around the highly variable X-ray binary GRS 1915+105, which includes a black hole and a K-giant companion. Based on the above, we can assume that the process of star formation in the young IRAS clusters was triggered by the GRS 915+105-initiated shock front inside the ISM massive condensation, through the process of "collecting and collapse". Most non-cluster objects probably belong to a later generation.

astro-ph.GA↗