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Optical Spectroscopy of Classical Be Stars in Old Open Clusters

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Research in Astronomy and Astrophysics 2023年第3期23卷 16-24页

作者： Madhu Kashyap Jagadeesh Blesson Mathew K.T.Paul Gourav Banerjee Suman Bhattacharyya R.Anusha Pramod Kumar S. Department of Physics and Electronics CHRIST(Deemed to be University)Hosur Main RoadBengaluruIndia Department of Physics and Astronomy University of Western OntarioON N6A 3K7Canada Indian Institute of Astrophysics KoramangalaBengaluruIndia

We performed the optical spectroscopy of 16 classical Be stars in 11 open clusters older than 100 *** is the first spectroscopic study of classical Be stars in open clusters older than 100 *** found that the Hαemission strength of most of the stars is less than 40?,in agreement with previous *** analysis further suggests that one of the stars,[KW97]35–12,might be a weak Hαemitter in nature,showing Hαequivalent width of-0.5?.Interestingly,we also found that the newly detected classical Be star LSⅢ+4737b might be a component of the possible visual binary system LSⅢ+4737,where the other companion is also a classical Be ***,the present study indicates the possible detection of a binary Be ***,it is observed that all 16 stars exhibit a lesser number of emission lines compared to classical Be stars younger than 100 ***,the spectral type distribution analysis of B-type and classical Be stars for the selected clusters points out that the existence of CBe stars can depend on the spectral type distribution of B-type stars present in these clusters.

关键词： clusters showing spectroscopic

Physical properties of three short period close binaries:KIC 2715417,KIC 6050116 and KIC 6287172

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Research in Astronomy and Astrophysics 2019年第2期19卷 111-124页

作者： Mahmoud AbdelFattah NegmEldin Ahmed Essam Elsayed Shahinaz Mostafa Yousef Astronomy Space Science and Meteorology Department Faculty of Science Cairo University Department of Astronomy National Research Institute of Astronomy and Geophysics(Egypt)

We present the physical parameters of three short period close binaries using data observed from the Kepler Space Telescope. All of these observations were taken in a single bandpass(which approximates the Johnson V-band). Our three systems are KIC 2715417, KIC 6050116 and KIC 6287172. The first system, KIC 2715417, is considered a semi-detached system with the secondary component filling its Roche lobe. The second system, KIC 6050116, is an overcontact system, while the third system, KIC 6287172, belongs to ellipsoidal variables as deduced from the Roche lobe geometry. For photometric analysis, we used the PHOEBE software package, which is based on the Wilson-Devinney code. Due to lack of spectroscopic data, the photometric mass ratios are determined from the analyses of light curves using the q-search method. The absolute parameters are determined using three different methods(Harmanec, Maceroni &Van'tVeer and Gazeas & Niarchos).

关键词： stars:binaries:eclipsing stars:fundamental parameters stars:luminosity function,mass function stars:individual(KIC 2715417,KIC 6050116 and KIC 6287172)

Liberation of SARS-CoV main protease from the viral polyprotein:N-terminal autocleavage does not depend on the mature dimerization mode

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Protein & Cell 2010年第3期1卷 59-74页

作者： Shuai Chen Felix Jonas Can Shen Rolf Higenfeld Institute of Biochemistry Center for Structural and Cell Biology in MedicineUniversity of LübeckRatzeburger Allee 16023538 LübeckGermany Laboratory for Structural Biology of Infection and Inflammation c/o DESYBuilding 22aNotkestr.8522603 HamburgGermany

The main protease(M^(pro))plays a vital role in proteolytic processing of the polyproteins in the replicative cycle of SARS coronavirus(SARS-CoV).Dimerization of this enzyme has been shown to be indispensable for transcleavage ***,the auto-processing mechanism of M^(pro),*** own release from the polyproteins through autocleavage,remains *** study elucidates the relationship between the N-terminal autocleavage activity and the dimerization of“immature”M^(pro).Three residues(Arg4,Glu290,and Arg298),which contribute to the active dimer conformation of mature M^(pro),are selected for mutational ***,all three mutants still perform N-terminal autocleavage,while the dimerization of mature protease and transcleavage activity following auto-processing are completely inhibited by the E290R and R298E mutations and partially so by the R4E ***,the mature E290R mutant can resume N-terminal autocleavage activity when mixed with the“immature”C145A/E290R double mutant whereas its trans-cleavage activity remains ***,the N-terminal auto-processing of M^(pro) appears to require only two“immature”monomers approaching one another to form an“intermediate”dimer structure and does not strictly depend on the active dimer conformation existing in mature *** conclusion,an auto-release model of M^(pro) from the polyproteins is proposed,which will help understand the auto-processing mechanism and the difference between the autocleavage and trans-cleavage proteolytic activities of SARS-CoV M^(pro).

关键词： SARS-CoV M^(pro) N-terminal autocleavage autocleavage activity trans-cleavage activity dimerization

COXSACKIEVIRUS 3C PROTEINASE AS A TARGET FOR ANTIVIRAL CHEMOTHERAPY

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COXSACKIEVIRUS 3C PROTEINASE AS A TARGET FOR ANTIVIRAL CHEMO...