期刊文献+
共找到424篇文章
< 1 2 22 >
每页显示 20 50 100
Variable Stars in the 50BiN Open Cluster Survey.Ⅲ.NGC 884
1
作者 Lin-Hong Wang Qian-Heng Nie +5 位作者 Kun Wang Xiao-Dian Chen Chun-Guang Zhang Li-Cai Deng Xiao-Bin Zhang Tian-Lu Chen 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第2期36-45,共10页
Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal ... Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host cluster.The most powerful tool for such studies is time-domain photometric observations.This paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC 884.The target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally bound.From the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were obtained.We detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown types.Two new variable stars were discovered in this work.We also compared the variable star content of NGC 884 with its companion NGC 869. 展开更多
关键词 stars variables general-(Galaxy:)open clusters and associations individual(… …)-(stars:)binaries GENERAL
下载PDF
Revise Thermal Winds of Remnant Neutron Stars in Gamma-Ray Bursts
2
作者 Shuang Du Tingting Lin +1 位作者 Shujin Hou Renxin Xu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第9期142-147,共6页
It seems that the wealth of information revealed by the multi-messenger observations of the binary neutron star(NS)merger event,GW170817/GRB 170817A/kilonova AT2017gfo,places irreconcilable constraints to models of th... It seems that the wealth of information revealed by the multi-messenger observations of the binary neutron star(NS)merger event,GW170817/GRB 170817A/kilonova AT2017gfo,places irreconcilable constraints to models of the prompt emission of this gamma-ray burst(GRB).The observed time delay between the merger of the two NSs and the trigger of the GRB and the thermal tail of the prompt emission can hardly be reproduced by these models simultaneously.We argue that the merger remnant should be an NS(last for,at least,a large fraction of 1 s),and that the difficulty can be alleviated by the delayed formation of the accretion disk due to the absorption of high-energy neutrinos emitted by the NS and the delayed emergence of effective viscosity in the disk.Further,we extend the consideration of the effect of the energy deposition of neutrinos emitted from the NS.If the NS is the central object of a GRB with a distance and duration similar to that of GRB 170817A,thermal emission of the thermal bubble inflated by the NS after the termination of accretion may be detectable.If our scenario is verified,it would be of interest to investigate the cooling of nascent NSs. 展开更多
关键词 (stars )gamma-ray burst general-(stars )gamma-ray burst individual(.. ...)-stars NEUTRON
下载PDF
First Light Curve Analysis of NSVS 8294044,V1023 Her,and V1397 Her Contact Binary Systems 被引量:1
3
作者 Atila Poro Sabrina Baudart +7 位作者 Mahshid Nourmohammad Zahra Sabaghpour Arani Fatemeh Farhadi Selda Ranjbar Salehian Ahmad Sarostad Saeideh Ranjbaryan Iri Olya Maryam Hadizadeh AmirHossein Khodaei 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第5期1-12,共12页
The first photometric light curve investigation of the NSVS 8294044,V1023 Her,and V1397 Her binary systems is presented.We used ground-based observations for the NSVS 8294044 system and Transiting Exoplanet Survey Sat... The first photometric light curve investigation of the NSVS 8294044,V1023 Her,and V1397 Her binary systems is presented.We used ground-based observations for the NSVS 8294044 system and Transiting Exoplanet Survey Satellite data for V1023 Her and V1397 Her.The primary and secondary times of minima were extracted from al the data,and,by collecting the literature,a new ephemeris was computed for each system.Linear fits for the O-C diagrams were conducted using the Markov Chain Monte Carlo (MCMC) method.Light curve solutions were performed using the PHysics Of Eclipsing BinariEs Python code and the MCMC approach.The systems were found to be contact binary stars based on the fillout factor and mass ratio.V1023 Her showed the O’Connell effect and a cold starspot on the secondary component was required for the light curve solution.The absolute parameters of the system were estimated based on an empirical relationship between orbital period and mass.We presented a new T–M equation based on a sample of 428 contact binary systems and found that our three target systems were in good agreement with the fit.The positions of the systems were also depicted on the M–L,M–R,q–L_(ratio),and M_(tot)–J_(0)diagrams in the logarithmic scales. 展开更多
关键词 (stars:)binaries eclipsing-techniques photometric-stars individual(NSVS 8294044)
下载PDF
Supernova 1987A's Keyhole:A Long-lived Jet-pair in the Final Explosion Phase of Core-collapse Supernovae
4
作者 Noam Soker 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第7期89-94,共6页
I further study the manner by which a pair of opposite jets shape the“keyhole”morphological structure of the core-collapse supernova(CCSN)SN 1997A,now the CCSN remnant(CCSNR)1987A.By doing so,I strengthen the claim ... I further study the manner by which a pair of opposite jets shape the“keyhole”morphological structure of the core-collapse supernova(CCSN)SN 1997A,now the CCSN remnant(CCSNR)1987A.By doing so,I strengthen the claim that the jittering-jet explosion mechanism accounts for most,likely all,CCSNe.The“keyhole”structure comprises a northern low-intensity zone closed with a bright rim on its front and an elongated low-intensity nozzle in the south.This rim-nozzle asymmetry is observed in some cooling flow clusters and planetary nebulae that are observed to be shaped by jets.I build a toy model that uses the planar jittering jets pattern,where consecutive pairs of jets tend to jitter in a common plane,implying that the accreted gas onto the newly born neutron star at the late explosion phase flows perpendicular to that plane.This allows for a long-lived jet-launching episode.This long-lasting jet-launching episode launches more mass into the jets that can inflate larger pairs of ears or bubbles,forming the main jets'axis of the CCSNR that is not necessarily related to a possible pre-collapse core rotation.I discuss the relation of the main jets'axis to the neutron star's natal kick velocity. 展开更多
关键词 stars massive-(stars)supernovae general-(stars)supernovae individual(SN 1987A)-ISM supernova remnants-stars jets
下载PDF
Analysis of the Impact of the Blazhko Effect Both on the Van Hoof Effect and Radial Velocity Amplitude in the Star RR Lyr
5
作者 Y.El jariri F.L.Sefyani +5 位作者 A.Benhida Z.Benkhaldoun K.Kolenberg K.Chafouai A.Habib M.Sabil 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第6期253-272,共20页
The Van Hoof effect is a phase shift existing between the radial velocity curves of hydrogen and metallic lines within the atmosphere of pulsating stars.In this article,we present a study of this phenomenon through th... The Van Hoof effect is a phase shift existing between the radial velocity curves of hydrogen and metallic lines within the atmosphere of pulsating stars.In this article,we present a study of this phenomenon through the spectra of the brightest pulsating star RR Lyr of RR Lyrae stars recorded for 22 yr.We based ourselves,on the one hand,on 1268 spectra(41 nights of observation)recorded between the years 1994 and 1997 at the Observatory of Haute Provence(OHP,France)previously observed by Chadid and Gillet,and on the other hand on 1569 spectra(46nights of observation)recorded at our Oukaimeden Observatory(Morocco)between 2015 and 2016.Through this study,we have detected information on atmospheric dynamics that had not previously been detected.Indeed,the Van Hoof effect which results in a clear correlation between the radial velocities of hydrogen and those of the metallic lines has been observed and analyzed at different Blazhko phases.A correlation between the radial velocities of different metallic lines located in the lower atmosphere has been observed as well.For the first time,we were able to show that the amplitude of the radial velocity curves deduced from the lines of hydrogen and that of FeⅡ(λ4923.921?)increases toward the minimum of the Blazhko cycle and decreases toward the maximum of the same Blazhko cycle.Furthermore,we found that the Van Hoof effect is also modulated by the Blazhko effect.Thus,toward the minimum of the Blazhko cycle the Van Hoof effect is more visible and at the maximum of the Blazhko cycle,this effect is minimal.We also observed the temporal evolution of the amplitudes of the radial velocities of the lower and upper atmosphere.When observed over a long time,we can interpret it as a function of the Blazhko phases. 展开更多
关键词 stars:atmospheres stars:variables:RR Lyrae shock waves techniques:spectroscopic techniques:radial velocities stars:individual(RR Lyr)
下载PDF
The Energy Sources and the Explosion Mechanism of Ca-rich Supernova PTF 10iuv
6
作者 Qiu-Ping Huang Shan-Qin Wang +4 位作者 Tao Wang Wen-Pei Gan Deng-Wang Shi Liu-Yi Wang En-Wei Liang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第9期106-118,共13页
In this paper,we perform the detailed modeling for the light curves(LCs)of PTF 10iuv which is a calcium-rich(Ca-rich)supernova(SN)to constrain the physical properties of its ejecta and the energy sources,as well as th... In this paper,we perform the detailed modeling for the light curves(LCs)of PTF 10iuv which is a calcium-rich(Ca-rich)supernova(SN)to constrain the physical properties of its ejecta and the energy sources,as well as the explosion mechanism.We find that the^(56)Ni model and the56Ni plus circumstellar interaction model fail to explain the LCs,while the four-element(^(56)Ni,^(48)Cr,^(52)Fe,and^(44)Ti)model can account for the LCs.The ejecta mass of PTF10iuv derived by the model(1.52_(-0.25)^(+0.34)M_(⊙))is consistent with that of the merger of a sub-Chandrasekhar mass white dwarf.The early-time LCs were mainly powered by^(56)Ni whose mass is~0.03 M_(⊙),while the contributions of^(48)Cr and^(52)Fe can be neglected.The derived^(44)Ti mass(~0.25 M_(⊙))is~1.8 times the upper limit of the derived^(44)Ti mass of Ca-rich SN 2005E.We suggest that subtracting the contributions of the host-galaxy,which are unknown,and including the flux from other long-lived elements(e.g.,^(57)Co,^(55)Fe,^(60)Co)can reduce the amount of^(44)Ti,and that this value can be regarded as an upper limit. 展开更多
关键词 (stars:)supernovae:general (stars:)supernovae:individual(PTF 10iuv) (stars:)novae cataclysmic variables
下载PDF
GRB 210323A:Signature of Long-lasting Lifetime of Supra-massive Magnetar as the Central Engine from the Merger of Binary Neutron Star
7
作者 Yingze Shan Xiaoxuan Liu +2 位作者 Xing Yang Haoyu Yuan Houjun Lü 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第8期32-41,共10页
Theoretically,a supra-massive neutron star or magnetar may be formed after the merger of binary neutron stars.GRB210323A is a short-duration gamma-ray burst(GRB)with a duration of lasting~1 s.The light curve of the pr... Theoretically,a supra-massive neutron star or magnetar may be formed after the merger of binary neutron stars.GRB210323A is a short-duration gamma-ray burst(GRB)with a duration of lasting~1 s.The light curve of the prompt emission of GRB 210323A shows a signal-peaked structure and a cutoff power-law model can adequately fit the spectra with E_p=1826±747.More interestingly,it has an extremely long-lasting plateau emission in the X-ray afterglow with a duration of~10^(4)s,and then follows a rapid decay with a decay slope~3.2.This temporal feature is challenging by invoking the external shock mode.In this paper,we suggest that the observed long-lasting X-ray plateau emission is caused by the energy injection of dipole radiation from supra-massive magnetar,and the abrupt decay following the longlasting X-ray plateau emission is explained by supra-massive magnetar collapsing into a black hole.It is the short GRB(SGRB)with the longest X-ray internal plateau emission powered by a supra-massive neutron star.If this is the case,one can estimate the physical parameters of a supra-massive magnetar,and compare with other SGRBs.We also discuss the possible gravitational-wave emission,which is powered by a supra-massive magnetar and its detectability,and the possible kilonova emission,which is powered by r-process and magnetar spin-down to compare with the observed data. 展开更多
关键词 (stars)gamma-ray burst general-(stars)gamma-ray burst individual(GRB 210323A)-stars MAGNETARS
下载PDF
BSN:The First Light Curve Analysis of the Total Eclipse Binary System EL Tuc
8
作者 Elham Sarvari Eduardo Fernández Lajús Atila Poro 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第10期66-75,共10页
We conducted the first light curve study of the binary star EL Tuc within the Binary Systems of South and North project's framework.The photometric observations were made using standard multiband BVR_cI_c filters ... We conducted the first light curve study of the binary star EL Tuc within the Binary Systems of South and North project's framework.The photometric observations were made using standard multiband BVR_cI_c filters at an observatory in Argentina.We presented a new ephemeris for EL Tuc and a linear fit to the O–C diagram,utilizing our extracted times of minima and additional literature.We employed the PHysics Of Eclipsing BinariEs Python code and the Markov chain Monte Carlo approach for the system's light curve analysis.The target system's light curve solution required a cold starspot on the hotter component.We conclude that EL Tuc is a total contact binary system with a low mass ratio of q=0.172±0.002,an orbital inclination of i=83°.74±0°.40,and a fillout factor of f=53.7%±1.6%.We used the P-a relationship and the Gaia Data Release 3 parallax method to determine the absolute parameters of EL Tuc to compare the precision of our results.This system was classified as W-type based on the mass and effective temperature of the companion stars.The positions of the systems were depicted on the M-L,M-R,T-M,and q-Lratiodiagrams.The relationship between the spectroscopic and photometric mass ratios of binaries was discussed. 展开更多
关键词 (stars:)binaries:eclipsing stars:individual(EL Tuc) line:identification
下载PDF
GRB 210610B:The Internal and External Plateau as Evidence for the Delayed Outflow of Magnetar
9
作者 Yi-Ning Wei Xiang-Gao Wang +8 位作者 Da-Bin Lin Wei-Kang Zheng Liang-Jun Chen Sheng-Yu Yan Shuang-Xi Yi Qi Wang Zi-Min Zhou Hui-Ya Liu En-Wei Liang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第7期170-180,共11页
After launching a jet,outflows of magnetar were used to account for the achromatic plateau of afterglow and the early X-ray flux plateau known as“internal plateau”.The lack of detecting magnetic dipole emission toge... After launching a jet,outflows of magnetar were used to account for the achromatic plateau of afterglow and the early X-ray flux plateau known as“internal plateau”.The lack of detecting magnetic dipole emission together with the energy injection feature in a single observation poses confusion until the long gamma-ray burst(GRB)210610B is detected.GRB 210610B is presented with an optical bump following an early X-ray plateau during the afterglow phase.The plateau followed by a steep decline flux overlays in the steadily decaying X-ray flux with indexα_(X,1)~2.06,indicating an internal origin and that can be fitted by the spin-down luminosity law with the initial plateau luminosity log_(10)L_(X)~48.29 erg s~(-1)and the characteristic spin-down timescale T~2818 s.A subsequent bump begins at~4000 s in the R band with a rising indexα_(R,1)~-0.30 and peaks at~14125 s,after which a decay indexα_(R,2)~0.87 and finally transiting to a steep decay withα_(R,3)~1.77 achieve the closure relation of the external shock for the normal decay phase as well as the magnetar spin-down energy injection phase,provided that the average value of the photon indexΓ_γ=1.80 derived from the spectral energy distributions(SEDs)between the X-ray and optical afterglow.The closure relation also works for the late X-ray flux.Akin to the traditional picture of GRB,the outflow powers the early X-ray plateau by dissipating energy internally and collides with the leading decelerating blast burst as time goes on,which could interpret the exotic feature of GRB 210610B.We carry out a Markov Chain Monte Carlo simulation and obtain a set of best parameters:■.The artificial light curve can fit the afterglow data well.After that,we estimated the average Lorentz factor and the X-ray radiation efficiency of the later ejecta are 35%and 0.13%,respectively. 展开更多
关键词 (stars)gamma-ray burst individual(GRB 210610B)-(stars)gamma-ray burst general-stars jets
下载PDF
GRB 200612A:An Ultralong Gamma-Ray Burst Powered by Magnetar Spinning Down
10
作者 陈良军 王祥高 +1 位作者 杨德龙 梁恩维 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第2期190-195,共6页
GRB 200612A could be classified as an ultralong gamma-ray burst due to its prompt emission lasting up to~1020 s and the true timescale of the central engine activity t_(burst)≥4×10^(4) s.The late X-ray light cur... GRB 200612A could be classified as an ultralong gamma-ray burst due to its prompt emission lasting up to~1020 s and the true timescale of the central engine activity t_(burst)≥4×10^(4) s.The late X-ray light curve with a decay index ofα=7.53 is steeper than the steepest possible decay from an external shock model.We propose that this X-ray afterglow can be driven by dipolar radiation from the magnetar spindown during its early stage,while the magnetar collapsed into the black hole before its spindown,resulting in a very steep decay of the late X-ray light curve.The optical data show that the light curve is still rising after 1.1 ks,suggesting a late onset.We show that GRB 200612A’s optical afterglow light curve is fitted with the forward shock model by Gaussian structured off-axis jet.This is a special case among GRBs,as it may be an ultralong gamma-ray burst powered by a magnetar in an off-axis observation scenario. 展开更多
关键词 (stars:)gamma-ray burst individual(GRB 200612A)-(stars:)gamma-ray burst general-stars MAGNETARS
下载PDF
V0405 Dra:A New Deep and Low Mass Ratio Contact Binary with Extremely Fast Decrease in the Orbital Period
11
作者 Chao-Yue Li Lin-Qiao Jiang +5 位作者 Jie Zheng Yi-Man Liu Xiao-Yu Long Min Sun Han-Lu Zhang Xiao-Man Tian 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第6期287-293,共7页
V0405 Dra is a W UMa-type binary star.Based on the TESS data,we have conducted an orbital period study and performed a light curve analysis for the system.The orbital period study reveals that the O-C curve for V0405 ... V0405 Dra is a W UMa-type binary star.Based on the TESS data,we have conducted an orbital period study and performed a light curve analysis for the system.The orbital period study reveals that the O-C curve for V0405 Dra exhibits secular decrease at an extremely high rate of d P/dt=-2.71×10^(-6)day year^(-1),along with periodic variations characterized by an amplitude of A_(3)=0.0032 day and a period of P_(3)=1.413 years.The orbital periodic change is possibly due to the light-travel time effect resulting from an additional third body in the system,for which we estimate a minimum mass of M_(3)=0.77M_(⊙).By employing the 2013 version of the Wilson-Devinney(W-D)method to synthesize a light curve,we derived photometric solutions indicating that V0405 Dra is a new deep(f=68.7%)and low-mass ratio(q=0.175)contact binary.The fast decrease in its orbital period is likely caused by mass transfer from the more massive primary star to the less massive secondary star,or due to angular momentum loss.With further mass transfer and loss of angular momentum,the binary will gradually evolve into a tighter contact configuration,eventually leading to a merger into a single star,following the evolutionary paths suggested for such deep and low mass ratio contact binaries. 展开更多
关键词 (stars:)binaries(including multiple):close (stars:)binaries:eclipsing stars:individual(V0405 Dra)
下载PDF
A Study of 10 Rotating Radio Transients Using Parkes Radio Telescope
12
作者 Xinhui Ren Jingbo Wang +4 位作者 Wenming Yan Jintao Xie Shuangqiang Wang Yirong Wen Yong Xia 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第4期114-123,共10页
Rotating Radio Transients(RRATs)are a relatively new subclass of pulsars that emit detectable radio bursts sporadically.We analyzed 10 RRATs observed using the Parkes telescope,with eight of these observed via the ult... Rotating Radio Transients(RRATs)are a relatively new subclass of pulsars that emit detectable radio bursts sporadically.We analyzed 10 RRATs observed using the Parkes telescope,with eight of these observed via the ultra-wide-bandwidth low-frequency(UWL)receiver.We measured the burst rate and produced integrated profiles spanning multiple frequency bands for three RRATs.We also conducted a spectral analysis on both integrated pulses and individual pulses of three RRATs.All of their integrated pulses follow a simple power law,consistent with the known range of pulsar spectral indices.Their average spectral indices of single pulses are-0.9,-1.2,and-1.0 respectively,which are within the known range of pulsar spectral indices.Additionally,we find that the spreads of single-pulse spectral indices for these RRATs(ranging from-3.5 to+0.5)are narrower compared to what has been observed in other RRATs.Notably,the average spectral index and scatter of single pulses are both relatively small.For the remaining five RRATs observed at the UWL receiver,we also provide the upper limits on fluence and flux density.In addition,we obtain the timing solution of PSR J1709-43.Our analysis shows that PSRs J1919+1745,J1709-43,and J1649-4653 are potentially nulling pulsars or weak pulsars with sparse strong pulses. 展开更多
关键词 (stars:)pulsars:general stars:neutron stars:individual(PSRs J1919+1745.1909+0641 0628+0909)
下载PDF
BSN:Photometric Light Curve Analysis of Two Contact Binary Systems LS Del and V997 Cyg
13
作者 Atila Poro Mehmet Tanriver +9 位作者 Elham Sarvari Shayan Zavvarei Hossein Azarara Laurent Corp Sabrina Baudart Asma Ababafi Nazanin Kahali Poor Fariba Zare Ahmet Bulut Ahmet Keskin 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第4期192-213,共22页
The light curve analyses and orbital period variations for two contact binary stars,LS Del and V997 Cyg,are presented in this work which was conducted in the frame of the Binary Systems of South and North project Grou... The light curve analyses and orbital period variations for two contact binary stars,LS Del and V997 Cyg,are presented in this work which was conducted in the frame of the Binary Systems of South and North project Ground-based photometric observations were performed at two observatories in France.We used the Transiting Exoplanet Survey Satellite(TESS)data for extracting times of minima and light curve analysis of the targe systems.The O-C diagram for both systems displays a parabolic trend.LS Del and V997 Cyg’s orbital periods are increasing at rates of dP/dt=7.20×10^(-08)days yr^(-1)and dP/dt=2.54×10^(-08)days yr^(-1),respectively Therefore,it can be concluded that mass is being transferred from the less massive star to the more massive component with a rate of dM/dt=-1.96×10^(-7)M_(⊙)yr^(-1)for the LS Del system,and dM/dt=-3.83×10^(-7)M_(⊙)yr-1for V997 Cyg.The parameters of a third possible object in the system are also considered.The PHysics Of Eclipsing BinariEs Python code was used to analyze the light curves.The light curve solutions needed a cold starspot due to the asymmetry in the LS Del system’s light curve maxima.The mass ratio fill-out factor,and star temperature all indicate that both systems are contact binary types in this investigation.Two methods were applied to estimate the absolute parameters of the systems:one method relied on the parallax of Gaia DR3,and the other used a P-M relationship.The positions of the systems are also depicted on the M-L,M-R q-L_(ratio),and logM_(tot)-logJ_(0)diagrams.We recommend that further observations and investigations be done on the existence of a fourth body in this system. 展开更多
关键词 (stars:)binaries:eclipsing methods:observational stars:individual(LS Del and V997 Cyg)
下载PDF
Spin Evolution of the Magnetar SGR J1935+2154
14
作者 Ming-Yu Ge Yuan-Pei Yang +11 位作者 Fang-Jun Lu Shi-Qi Zhou Long Ji Shuang-Nan Zhang Bing Zhang Liang Zhang Pei Wang Kejia Lee Weiwei Zhu Jian Li Xian Hou Qiao-Chu Li 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第1期201-211,共11页
Fast radio bursts(FRBs)are short pulses observed in radio frequencies usually originating from cosmological distances.The discovery of FRB 200428 and its X-ray counterpart from the Galactic magnetar SGR J1935+2154sugg... Fast radio bursts(FRBs)are short pulses observed in radio frequencies usually originating from cosmological distances.The discovery of FRB 200428 and its X-ray counterpart from the Galactic magnetar SGR J1935+2154suggests that at least some FRBs can be generated by magnetars.However,the majority of X-ray bursts from magnetars are not associated with radio emission.The fact that only in rare cases can an FRB be generated raises the question regarding the special triggering mechanism of FRBs.Here we report long time spin evolution of SGR J1935+2154 until the end of 2022.According to v and v,the spin evolution of SGR J1935+2154 could be divided into two stages.The first stage evolves relatively steady evolution until 2020 April 27.After the burst activity in2020,the spin of SGR J1935+2154 shows strong variations,especially for v.After the burst activity in 2022October,a new spin-down glitch with△v/v=(-7.2±0.6)×10^(-6)is detected around MJD 59876,which is the second event in SGR J1935+2154.At the end,spin frequency and pulse profile do not show variations around the time of FRB 200428 and radio bursts 221014 and 221021,which supply strong clues to constrain the trigger mechanism of FRBs or radio bursts. 展开更多
关键词 (stars:)pulsars:general (stars:)pulsars:individual(SGR J1935+2154) X-rays:bursts
下载PDF
The Bright Single Pulse Emission from PSR B1133+16
15
作者 Jun Tan Zhi-Gang Wen +12 位作者 Zhen Wang Xue-Feng Duan Hong-Guang Wang Na Wang Vishal Gajjar Jian-Ping Yuan Rai Yuen Wen-Ming Yan Jian-Ling Chen Wei Han Hui Wang Cheng-Bing Lyu Ai-Jun Dong 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第4期253-261,共9页
We have conducted a comprehensive investigation into the bright single pulse emission from PSR B1133+16using the Giant Metrewave Radio Telescope.High time resolution data(61μs)were obtained at a center frequency of 3... We have conducted a comprehensive investigation into the bright single pulse emission from PSR B1133+16using the Giant Metrewave Radio Telescope.High time resolution data(61μs)were obtained at a center frequency of 322 MHz with a bandwidth of 32 MHz over a continuous observation period of 7.45 hr.A total of 1082 bright pulses were sporadically detected with peak flux densities ranging from 10 to 23 times stronger than the average pulse profile.However,no giant pulse-like emission with a relative pulse energy larger than 10 and extremely short duration was detected,indicating that these bright pulses cannot be categorized as giant pulse emission.The majority of these bright pulses are concentrated in pulse phases at both the leading and trailing windows of the average pulse profile,with an occurrence ratio of approximately 2.74.The pulse energy distribution for all individual pulses can be described by a combination of two Gaussian components and a cutoff power-law with an index of α=-3.2.An updated nulling fraction of 15.35%±0.45% was determined from the energy distribution.The emission of individual pulses follows a log-normal distribution in peak flux density ratio.It is imperative that regular phase drifting in bright pulse sequence is identified in both the leading and trailing components for the first time.Possible physical mechanisms are discussed in detail to provide insights into these observations. 展开更多
关键词 (stars:)pulsars:general (stars:)pulsars:individual(PSR B1133+16) methods:observational methods:data analysis
下载PDF
Fast Two-dimensional Positioning Method of Crab Pulsar Based on Multiple Optimization Algorithms
16
作者 Jianfeng Chen Jin Liu +1 位作者 Xin Ma Xiaolin Ning 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第10期92-103,共12页
In the two-dimensional positioning method of pulsars, the grid method is used to provide non-sensitive direction and positional estimates. However, the grid method has a high computational load and low accuracy due to... In the two-dimensional positioning method of pulsars, the grid method is used to provide non-sensitive direction and positional estimates. However, the grid method has a high computational load and low accuracy due to the interval of the grid. To improve estimation accuracy and reduce the computational load, we propose a fast twodimensional positioning method for the crab pulsar based on multiple optimization algorithms(FTPCO). The FTPCO uses the Levenberg–Marquardt(LM) algorithm, three-point orientation(TPO) method, particle swarm optimization(PSO) and Newton–Raphson-based optimizer(NRBO) to substitute the grid method. First, to avoid the influence of the non-sensitive direction on positioning, we take an orbital error and the distortion of the pulsar profile as optimization objectives and combine the grid method with the LM algorithm or PSO to search for the non-sensitive direction. Then, on the sensitive plane perpendicular to the non-sensitive direction, the TPO method is proposed to fast search the sensitive direction and sub-sensitive direction. Finally, the NRBO is employed on the sensitive and sub-sensitive directions to achieve two-dimensional positioning of the Crab pulsar. The simulation results show that the computational load of the FTPCO is reduced by 89.4% and the positioning accuracy of the FTPCO is improved by approximately 38% compared with the grid method. The FTPCO has the advantage of high real-time accuracy and does not fall into the local optimum. 展开更多
关键词 (stars:)pulsars:individual(Crab pulsar) space vehicles methods:data analysis ASTROMETRY
下载PDF
Study of Complex Nitrogen and Oxygen-bearing Molecules toward the High-mass Protostar IRAS 18089–1732
17
作者 Arijit Manna Sabyasachi Pal +1 位作者 Tapas Baug Sougata Mondal 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第6期81-93,共13页
The observation of oxygen(O)-and nitrogen(N)-bearing molecules gives an idea about the complex prebiotic chemistry in the interstellar medium.Recent millimeter and submillimeter wavelength observations have shown the ... The observation of oxygen(O)-and nitrogen(N)-bearing molecules gives an idea about the complex prebiotic chemistry in the interstellar medium.Recent millimeter and submillimeter wavelength observations have shown the presence of complex O-and N-bearing molecules in the star formation regions.So,the investigation of those molecules is crucial to understanding the chemical complexity in the star-forming regions.In this article,we present the identification of the rotational emission lines of N-bearing molecules ethyl cyanide(C_(2)H_(5)CN)and cyanoacetylene(HC_(3)N),and O-bearing molecule methyl formate(CH_(3)OCHO)toward high-mass protostar IRAS18089–1732 using the Atacama Compact Array.We also detected the emission lines of both the N-and O-bearing molecule formamide(NH_(2)CHO)in the envelope of IRAS 18089–1732.We have detected the v=0 and 1 state rotational emission lines of CH_(3)OCHO.We also detected the two vibrationally excited states of HC_(3)N(v7=1 and v7=2).The estimated fractional abundances of C_(2)H_(5)CN,HC_(3)N(v7=1),HC_(3)N(v7=2),and NH_(2)CHO toward IRAS 18089–1732 are(1.40±0.5)×10^(-10),(7.5±0.7)×10^(-11),(3.1±0.4)×10^(-11),and(6.25±0.82)×10^(-11)respectively.Similarly,the estimated fractional abundances of CH_(3)OCHO(v=0)and CH_(3)OCHO(v=1)are(1.90±0.9)×10^(-9)and(8.90±0.8)×10^(-10),respectively.We also created the integrated emission maps of the detected molecules,and the observed molecules may have originated from the extended envelope of the protostar.We show that C_(2)H_(5)CNand HC_(3)N are most probably formed via the subsequential hydrogenation of the CH_(2)CHCNand the reaction between C_(2)H_(2)and CN on the grain surface of IRAS 18089–1732.We found that NH_(2)CHO is probably produced due to the reaction between NH_(2)and H_(2)CO in the gas phase.Similarly,CH_(3)OCHO is possibly created via the reaction between radical CH_(3)O and radical HCO on the grain surface of IRAS 18089–1732. 展开更多
关键词 ISM:individual objects(IRA 18089-1732)(except) ISM:abundances ISM:kinematics and dynamics stars:formation ASTROCHEMISTRY
下载PDF
A Possible γ-Ray Pulsation from PSR J1740-5340B in the Globular Cluster NGC 6397
18
作者 Jiao Zheng Pengfei Zhang Li Zhang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第1期285-291,共7页
Recently, a new radio millisecond pulsar(MSP) J1740-5340B, hosted in the globular cluster(GC) NGC 6397,was reported with a 5.78 ms spin period in an eclipsing binary system with a 1.97 days orbital period. Based on a ... Recently, a new radio millisecond pulsar(MSP) J1740-5340B, hosted in the globular cluster(GC) NGC 6397,was reported with a 5.78 ms spin period in an eclipsing binary system with a 1.97 days orbital period. Based on a modified radio ephemeris updated by tool tempo2, we analyze the ~15 yr γ-ray data obtained from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detect PSR J1740-5340B's γ-ray pulsation at a confidence level of ~4σ with a weighted H-test value of ~26. By performing a phase-resolved analysis, the γ-ray luminosity in on-pulse interval of PSR J1740-5340B is L_(γ)~ 3.8 × 10^(33) erg s^(-1) using NGC 6397's distance of 2.48 kpc. And γ-rays from the on-pulse part of PSR J1740-5340B contribute ~90% of the total observed γ-ray emissions from NGC 6397. No significant γ-ray pulsation of another MSP J1740-5340A in the GC is detected.Considering that the previous four cases of MSPs in GCs, more data in γ-ray, X-ray, and radio are encouraged to finally confirm the γ-ray emissions from MSP J1740-5340B, especially starving for a precise ephemeris. 展开更多
关键词 gamma-rays:galaxies (stars:)pulsars:individual(PSR J1740-5340B) (Galaxy:)globular clusters:individual(NGC 6397)
下载PDF
The RFI Fast Mitigation Algorithm Based on Block LMS Filter
19
作者 Han Wu Hai-Long Zhang +4 位作者 Ya-Zhou Zhang Jie Wang Xu Du Ting Zhang Xin-Chen Ye 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第1期265-272,共8页
The radio telescope possesses high sensitivity and strong signal collection capabilities.While receiving celestial radiation signals,it also captures Radio Frequency Interferences(RFIs)introduced by human activities.R... The radio telescope possesses high sensitivity and strong signal collection capabilities.While receiving celestial radiation signals,it also captures Radio Frequency Interferences(RFIs)introduced by human activities.RFI,as signals originating from sources other than the astronomical targets,significantly impacts the quality of astronomical data.This paper presents an RFI fast mitigation algorithm based on block Least Mean Square(LMS)algorithm.It enhances the traditional adaptive LMS filter by grouping L adjacent time-sampled points into one block and applying the same filter coefficients for filtering within each block.This transformation reduces multiplication calculations and enhances algorithm efficiency by leveraging the time-domain convolution theorem.The algorithm is tested using baseband data from the Parkes 64 m radio telescope's pulsar observations and simulated data.The results confirm the algorithm's effectiveness,as the pulsar profile after RFI mitigation closely matches the original pulsar profile. 展开更多
关键词 methods:data analysis techniques:interferometric (stars:)pulsars:individual(J0437-4715)
下载PDF
Isochrone Fitting of Galactic Globular Clusters—Ⅵ.High-latitude Clusters NGC 5024 (M53),NGC 5053,NGC 5272 (M3),NGC 5466,and NGC7099 (M30)
20
作者 G.A.Gontcharov S.S.Savchenko +7 位作者 A.A.Marchuk C.J.Bonatto O.S.Ryutina M.Yu.Khovritchev V.B.Il'in A.V.Mosenkov D.M.Poliakov A.A.Smirnov 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第6期170-190,共21页
We fit various color–magnitude diagrams(CMDs) of the high-latitude Galactic globular clusters NGC 5024(M53),NGC 5053,NGC 5272(M3),NGC 5466,and NGC 7099(M30) by isochrones from the Dartmouth Stellar Evolution Database... We fit various color–magnitude diagrams(CMDs) of the high-latitude Galactic globular clusters NGC 5024(M53),NGC 5053,NGC 5272(M3),NGC 5466,and NGC 7099(M30) by isochrones from the Dartmouth Stellar Evolution Database and Bag of Stellar Tracks and Isochrones for α–enrichment [α/Fe] = +0.4.For the CMDs,we use data sets from Hubble Space Telescope,Gaia,and other sources utilizing,at least,25 photometric filters for each cluster.We obtain the following characteristics with their statistical uncertainties for NGC 5024,NGC 5053,NGC 5272,NGC 5466,and NGC 7099,respectively:metallicities [Fe/H] =-1.93 ± 0.02,-2.08 ± 0.03,-1.60 ± 0.02,-1.95 ± 0.02,and-2.07 ± 0.04 dex with their systematic uncertainty 0.1 dex;ages 13.00 ± 0.11,12.70 ± 0.11,11.63 ± 0.07,12.15 ± 0.11,and 12.80 ± 0.17 Gyr with their systematic uncertainty 0.8 Gyr;distances(systematic uncertainty added) 18.22 ± 0.06 ± 0.60,16.99 ± 0.06 ± 0.56,10.08 ± 0.04 ± 0.33,15.59 ±0.03 ± 0.51,and 8.29 ± 0.03 ± 0.27 kpc;reddenings E(B-V) = 0.023 ± 0.004,0.017 ± 0.004,0.023 ± 0.004,0.023 ± 0.003,and 0.045 ± 0.002 mag with their systematic uncertainty 0.01 mag;extinctions AV= 0.08 ± 0.01,0.06 ± 0.01,0.08 ± 0.01,0.08 ± 0.01,and 0.16 ± 0.01 mag with their systematic uncertainty 0.03 mag,which suggest the total Galactic extinction AV= 0.08 across the whole Galactic dust to extragalactic objects at the North Galactic Pole.The horizontal branch morphology difference of these clusters is explained by their different metallicity,age,mass-loss efficiency,and loss of low-mass members in the evolution of the core-collapse cluster NGC 7099 and loose clusters NGC 5053 and NGC 5466. 展开更多
关键词 (stars:)Hertzsprung Russell and C-M diagrams (ISM:)dust extinction (Galaxy:)globular clusters:general (Galaxy:)globular clusters:individual(NGC 5024 NGC 5053 NGC 5272 NGC 5466 NGC7099)
下载PDF
上一页 1 2 22 下一页 到第
使用帮助 返回顶部