arXiv subjects

Hicran Bakış

Publications and source records attributed to Hicran Bakış.

3 recordsLinked to original sources

arXiv2026

Optical observations and atomic environment of supernova remnant G25.1-2.3

The supernova remnant (SNR) G25.1-2.3 was identified in the radio band during the Sino-German $λ$6 cm survey of the Galactic plane. We present a detailed investigation of the optical, HI, and CO emission towards the G25.1-2.3 to better understand its characteristics and environment. In this study, optical spectroscopic data of the remnant and its environment have been analysed for the first time, providing new insights into their emission properties. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and 1.5-m Russian-Turkish Telescope (RTT150) data show variations across the observed regions, with [SII]/H$α$ ranging from 0.16 to 0.83. We identified shock-heated gas in the northern and southern regions and several photoionized regions around the SNR based on their [SII]/H$α$ ratios derived from spectra. The [SII]$λ$6716/$λ$6731 ratio observed in the northern region suggests electron densities ($n_{\rm e}$) ranging from 120 to 1030 cm$^{-3}$, whereas the southern regions show higher values, between 490 and 4500 cm$^{-3}$. The variations in the observed H$α$/H$β$ ratios indicate significant differences in extinction across the regions. H$α$ images obtained using the 1-m Turkish Telescope (T100) reveal optical emission in the northern and southern, characterized by filamentary and diffuse structures. We newly found a hole-like distribution of HI, whose spatial extent is roughly consistent with the diameter of the SNR. Based on radio data, we examine the evolutionary stage of G25.1-2.3 using the surface brightness-diameter ($Σ-D$) relation and the equipartition method.

astro-ph.HE↗

arXiv2026

First detailed optical spectroscopic observations of the supernova remnants G107.7-5.1 and G150.3+4.5

We present optical spectroscopic observations of the supernova remnants (SNRs) G107.7$-$5.1 and G150.3+4.5, each spanning nearly 3 degree. Both remnants were recently examined in the optical band through a deep H$α$ and [OIII] emission-line imaging survey, which led to the discovery of G107.7$-$5.1. Using long-slit spectra obtained with the 1.5-m Russian-Turkish Telescope (RTT150), we investigate the physical conditions of the pre-shock and post-shock gas in the optical filamentary regions of the SNRs. The SNR nature of G107.7$-$5.1 is confirmed by the measured [SII]/H$α$ and [NII]/H$α$ ratios, which range from 0.56 to 0.86 and from 0.7 to 1.4, respectively. A similar conclusion is reached for G150.3+4.5, where the observed [SII]/H$α$ (0.43-0.92) and [NII]/H$α$ (0.49-1.29) ratios likewise support a shock-excitation origin. Further confirmation of the shock-excited nature of both SNRs comes from their consistency with recent diagnostic diagrams based on multiple emission-line ratios. The [OIII]/H$β$ line ratios measured in both remnants indicate shocks with complete recombination zones and are consistent with shock velocities of $\gtrsim$100 km s$^{-1}$. The electron densities ($n_{\rm e}$), derived from the [SII] $λ$6716/$λ$6731 line ratios, exhibit substantial variation in the spectra of both SNRs. Additionally, extinction variations observed across the remnants suggest the presence of significant dust structures along the line of sight. We conclude that these two remnants display remarkable similarities across multiple diagnostic spectral properties, consistent with previous reports indicating comparable GeV gamma-ray characteristics.

astro-ph.HE↗

arXiv2025

RS Sagittarii: Revealing the component spectra and the mass transfer

We present an analysis of high-resolution (R ~ 48000) spectroscopic and photometric data of RS Sgr, a short-period Algol-type binary system. For the first time, precise spectroscopic and absolute parameters of the system have been determined. The primary component is identified as a B3 main-sequence star with an effective temperature of 19000K, while the secondary is classified as an A0-type star with a temperature of 9700 K. The secondary appears to have recently evolved off the main sequence and currently fills its Roche lobe, transferring material through the inner Lagrangian point (L1) to the hotter primary component. The Hα emission and absorption features observed in the spectra are attributed to a combination of a low-density circumprimary disk, a gas stream originating from the secondary, and a hot spot formed at the impact site on the primary. The combined analysis of spectroscopic and photometric data yields a system distance of approximately 418 pc, which is consistent with the value derived from GAIA DR3 within the uncertainty limits.

astro-ph.SR↗