The star 1-1-42 （=vZ1390）, a cluster member in M3, located near the red edge of the instability strip of the horizontal branch, was discovered by Roberts and Sandage as a low amplitude variable, it was designated as...The star 1-1-42 （=vZ1390）, a cluster member in M3, located near the red edge of the instability strip of the horizontal branch, was discovered by Roberts and Sandage as a low amplitude variable, it was designated as V204 in the ＂second catalogue of variable stars in globular clusters＂, but its coordinates given in all versions of this catalogue are wrong since 1955. We argue that V204 is indeed a low amplitude HB variable star, located near to the red edge of the instability strip, with a period of 0.74785d and an amplitude of about 0.04 mag in V. We also find that the red cluster member star 1-1-39 is a low amplitude variable with a period of 1.16^d and amplitude of about 0.03 mag in V which might be pulsating at the second overtone.展开更多
This paper presents a hadronic dominated jet model to investigate multi- wavelength emission from the microquasar LS I ＋61 303. In this scenario, we take into account evolutions of the primary particles and secondary...This paper presents a hadronic dominated jet model to investigate multi- wavelength emission from the microquasar LS I ＋61 303. In this scenario, we take into account evolutions of the primary particles and secondary e± pairs; these pairs are produced by the collisional interactions of the accelerated protons with the cold jet protons and the stellar wind ions. In this model, the non-thermal photons are produced by πο decay emission, synchrotron and inverse Compton scattering processes from the primary electrons and secondary pairs, and relativistic bremsstrahlung emission from the secondary leptonic pairs. Based on this model framework, we show that the spectral energy distributions can be produced by the primary and secondary particles via interactions with the cold matter, and magnetic and stellar radiation fields. We also consider the attenuation of angular dependence γ-γ due to the effects of the stel- lar target photon fields. The resulting model can approximately reproduce the recent quasi-simultaneous observational data points and the non-simultaneous multi-band observations.展开更多
In this paper, we study the age and spatial distributions of Cepheids in the Small Magellanic Cloud （SMC） as a function of their ages using data from the OGLE III photometric catalogue. A period - age relation deriv...In this paper, we study the age and spatial distributions of Cepheids in the Small Magellanic Cloud （SMC） as a function of their ages using data from the OGLE III photometric catalogue. A period - age relation derived for Classical Cepheids in the Large Magellanic Cloud （LMC） has been used to find the ages of Cepheids. The age distribution of the SMC Classical Cepheids is found to have a peak at log（Age） ： 8.40 ± 0.10 which suggests that a major star formation event might have occurred in the SMC about 250 4- 50 Myr ago. It is believed that this star forming burst had been triggered by close interactions of the SMC with the LMC and/or the Milky Way. A comparison of the observed spatial distributions of the Cepheids and open star clusters has also been carried out to study the star formation scenario in the SMC.展开更多
文摘The star 1-1-42 （=vZ1390）, a cluster member in M3, located near the red edge of the instability strip of the horizontal branch, was discovered by Roberts and Sandage as a low amplitude variable, it was designated as V204 in the ＂second catalogue of variable stars in globular clusters＂, but its coordinates given in all versions of this catalogue are wrong since 1955. We argue that V204 is indeed a low amplitude HB variable star, located near to the red edge of the instability strip, with a period of 0.74785d and an amplitude of about 0.04 mag in V. We also find that the red cluster member star 1-1-39 is a low amplitude variable with a period of 1.16^d and amplitude of about 0.03 mag in V which might be pulsating at the second overtone.
基金supported by the Guizhou provincial NaturalScience Foundation (Nos. 08097 and 2010080)the National Natural Science Foundation of China(NSFC, Grant Nos. 10778702 and 10803005)the National Basic Research Program of China(973 project 2009CB824800)
文摘This paper presents a hadronic dominated jet model to investigate multi- wavelength emission from the microquasar LS I ＋61 303. In this scenario, we take into account evolutions of the primary particles and secondary e± pairs; these pairs are produced by the collisional interactions of the accelerated protons with the cold jet protons and the stellar wind ions. In this model, the non-thermal photons are produced by πο decay emission, synchrotron and inverse Compton scattering processes from the primary electrons and secondary pairs, and relativistic bremsstrahlung emission from the secondary leptonic pairs. Based on this model framework, we show that the spectral energy distributions can be produced by the primary and secondary particles via interactions with the cold matter, and magnetic and stellar radiation fields. We also consider the attenuation of angular dependence γ-γ due to the effects of the stel- lar target photon fields. The resulting model can approximately reproduce the recent quasi-simultaneous observational data points and the non-simultaneous multi-band observations.
基金Indian Academy of Sciences(IASc),Bangalore for the financial assistance provided through the IAS-SRFP 2014the grant received under the Indo-Russian project INT/RUS/RFBR/P-219 funded by Department of Science and Technology,New Delhi
文摘In this paper, we study the age and spatial distributions of Cepheids in the Small Magellanic Cloud （SMC） as a function of their ages using data from the OGLE III photometric catalogue. A period - age relation derived for Classical Cepheids in the Large Magellanic Cloud （LMC） has been used to find the ages of Cepheids. The age distribution of the SMC Classical Cepheids is found to have a peak at log（Age） ： 8.40 ± 0.10 which suggests that a major star formation event might have occurred in the SMC about 250 4- 50 Myr ago. It is believed that this star forming burst had been triggered by close interactions of the SMC with the LMC and/or the Milky Way. A comparison of the observed spatial distributions of the Cepheids and open star clusters has also been carried out to study the star formation scenario in the SMC.
