Principal Component Analysis for Estimating Parameters of the L1287 Dense Core by Fitting Model Spectral Maps into Observed Ones     

Pirogov  L. E.  Zemlyanukha  P. M. 《Astronomy Reports》2021,65(2):82-94

Astronomy Reports - An algorithm has been developed for finding the global minimum of a multidimensional error function by fitting model spectral maps into observed ones. Principal component...  相似文献   

Multifrequency studies of massive cores with complex spatial and kinematic structures     

L. E. Pirogov  V. M. Shul’ga  I. I. Zinchenko  P. M. Zemlyanukha  A. N. Patoka  M. Tomasson 《Astronomy Reports》2016,60(10):904-923

Five regions of massive-star formation have been observed in various molecular lines in the frequency range～85?89 GHz. The studied regions comprise dense cores, which host young stellar objects. The physical parameters of the cores are estimated, including the kinetic temperatures (～20?40 K), the sizes of the emitting regions (～0.1?0.6 pc), and the virial masses (～40?500 M_⊙). The column densities and abundances of various molecules are calculated assuming Local Thermodynamical Equilibrium(LTE). The core in 99.982+4.17, which is associated with the weakest IRAS source, is characterized by reduced molecular abundances. The molecular line widths decrease with increasing distance from the core centers (b). For b ? 0.1 pc, the dependences ΔV (b) are close to power laws (∝b^?p), where p varies from ~0.2 to ~0.5, depending on the object. In four cores, the asymmetries of the optically thick HCN(1–0) and HCO⁺(1–0) lines indicates systematicmotions along the line of sight: collapse in two cores and expansion in two others. Approximate estimates of the accretion rates in the collapsing cores indicate that the forming stars have masses exceeding the solar mass.  相似文献   

A Survey of High Mass Star Forming Regions in the Lines of Deuterated Molecules     

Trofimova  E. A.  Zinchenko  I. I.  Zemlyanukha  P. M.  Thomasson  M. 《Astronomy Reports》2020,64(3):244-258

Astronomy Reports - A survey of massive star forming regions in the lines of the lowest transitions of deuterated molecules DCN, DNC, DCO+, N2D+ in the 4 mm wavelength range was performed using the...  相似文献   

The Spatial–Kinematic Structure of the Region of Massive Star Formation S255N on Various Scales     

P. M. Zemlyanukha  I. I. Zinchenko  S. V. Salii  O. L. Ryabukhina  S.-Y. Liu 《Astronomy Reports》2018,62(5):326-345

The results of a detailed analysis of SMA, VLA, and IRAM observations of the region of massive star formation S255N in CO(2–1), N₂H⁺(3–2), NH₃(1, 1), C¹⁸O(2–1) and some other lines is presented. Combining interferometer and single-dish data has enabled a more detailed investigation of the gas kinematics in the moleclar core on various spatial scales. There are no signs of rotation or isotropic compression on the scale of the region as whole. The largest fragments of gas (≈0.3 pc) are located near the boundary of the regions of ionized hydrogen S255 and S257. Some smaller-scale fragments are associated with protostellar clumps. The kinetic temperatures of these fragments lie in the range 10–80 K. A circumstellar torus with inner radius R_in ≈ 8000 AU and outer radius R_out ≈ 12 000 AU has been detected around the clump SMA1. The rotation profile indicates the existence of a central object with mass ≈8.5/ sin²(i) M_⊙. SMA1 is resolved into two clumps, SMA1–NE and SMA1–SE, whose temperatures are≈150Kand≈25 K, respectively. To all appearances, the torus is involved in the accretion of surrounding gas onto the two protostellar clumps.  相似文献   

Study of the filamentary infrared dark cloud G192.76+00.10 in the S254–S258 OB complex     

Olga L.Ryabukhina  Igor I.Zinchenko  Manash R.Samal  Petr M.Zemlyanukha  Dmitry A.Ladeyschikov  ANDrej M.Sobolev  Christian Henkel  Devendra K.Ojha 《天文和天体物理学研究(英文版)》2018,(8)

We present results of a high resolution study of the filamentary infrared dark cloud G192.76+00.10 in the S254-S258 OB complex in several molecular species tracing different physical conditions. These include three isotopologues of carbon monoxide(CO), ammonia(NH3) and carbon monosulfide(CS). The aim of this work is to study the general structure and kinematics of the filamentary cloud, and its fragmentation and physical parameters. The gas temperature is derived from the NH3(J, K) =(1,1),(2, 2) and ~(12)CO(2-1) lines, and the ~(13)CO(1-0), ~(13)CO(2-1) emission is used to investigate the overall gas distribution and kinematics. Several dense clumps are identified from the CS(2-1)data. Values of the gas temperature lie in the range 10-35 K, and column density N(H2) reaches the value 5.1 x 10~(22) cm~(-2). The width of the filament is of order 1 pc. The masses of the dense clumps range from ～ 30 M_☉ to ～ 160 M_☉. They appear to be gravitationally unstable. The molecular emission shows a gas dynamical coherence along the filament. The velocity pattern may indicate longitudinal collapse.  相似文献