Using the stellar evolution code MESA,we mimic the negative jet feedback mechanism in common envelope evolution(CEE)of low-mass main sequence stars,M_(2)?0.1-0.2M_(☉),spiraling inward inside the envelopes of asymptot...Using the stellar evolution code MESA,we mimic the negative jet feedback mechanism in common envelope evolution(CEE)of low-mass main sequence stars,M_(2)?0.1-0.2M_(☉),spiraling inward inside the envelopes of asymptotic giant branch or red giant branch stars and find that the jets reduced the envelope density,and therefore the jets'power,by a factor ofχ≈0.5(M_(2)/0.1M_(☉))^(-1).We mimic the energy that the jets deposit into the envelope by depositing energy into the outer envelope,a process that inflates the envelope,therefore reducing the density in the vicinity of the main sequence star,the accretion rate,and the jets'power.In deriving this expression for the negative jet feedback coefficientχ,we assume that the actual mass accretion rate is a fractionξ≈0.2-0.5 of the classical Bondi-Hoyle-Lyttleton mass accretion rate and that the jets carry a fractionη≈0.25-0.5 of the accretion energy onto the main sequence star.Our study is another step in establishing the major role of jets in the onset and early phase of CEE,a possible grazing envelope evolution phase,and in transient events,such as luminous red novae,which these processes can power.展开更多
The subclass of bipolar Planetary Nebulae(PNe)exhibits well-defined low-power outflows and some shows shock-related equatorial spiderweb structures and hourglass structures surrounding these outflows.These structures ...The subclass of bipolar Planetary Nebulae(PNe)exhibits well-defined low-power outflows and some shows shock-related equatorial spiderweb structures and hourglass structures surrounding these outflows.These structures are distinctly different from the phenomena associated with spherical and elliptical PNe and suggest a non-standard way to simultaneously energise both kinds of structures.This paper presents evidence from the published literature on bipolar PN Hb 12 and other sources in support of an alternative scenario for energising these structures by means of accretion from material shells deposited during earlier post-AGB and pre-PNe evolutionary stages.In addition to energising the bipolar outflow,a sub-Eddington accretion scenario could hydrodynamically explain the spiderweb and outer hourglass structures as oblique shockwaves for guiding the accreting material into the equatorial region of the source.Estimates of the accretion rate resulting from fallback-related spherical accretion could indeed help to drive a low-power outflow and contribute to the total luminosity of these sources.展开更多
Planetary nebulae （PNe） are good tracers of the stellar populations, chemical composition and dynamics of their host galaxies. This paper reports the discovery of new PNe in the outskirts of the Andromeda Galaxy （...Planetary nebulae （PNe） are good tracers of the stellar populations, chemical composition and dynamics of their host galaxies. This paper reports the discovery of new PNe in the outskirts of the Andromeda Galaxy （M31） with the Guoshoujing Telescope （GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope-LAMOST） during its early commissioning phase. In total, 36 candidates selected from SDSS photometry are confirmed in terms of their PN nature, including 17 new discoveries and another 19 previously known emission line objects. Their positions, spectra, radial velocities and m5007 magnitudes are presented. We discuss the potential for detecting more PNe in M 31 with GSJT＇s multi-object spectroscopy and the related applications in studies of the dynamics and chemistry of M 31 and its assemblage history.展开更多
The extremely accurate estimates of stellar variability and radial velocity in the Gaia Data Release 3(Gaia DR3)have enabled us to examine the close binarity and radial velocity(RV)of central stars(CSs)of planetary ne...The extremely accurate estimates of stellar variability and radial velocity in the Gaia Data Release 3(Gaia DR3)have enabled us to examine the close binarity and radial velocity(RV)of central stars(CSs)of planetary nebulae(PNe).This study is twofold:(1)searching for new close binary CS candidates to better understand how binarity affects the formation and evolution of PNe;and(2)extending the sample size of known RVs of PNe in order to understand their kinematics and the dynamics of the Milky Way.As a target sample,we used all true,possible,and likely PNe available in the literature.Then,we looked for their matched Gaia DR3 sources that provide measurements of variability and RV.As a result,we detected the first large collection of trustworthy photometric variability of 26 symbiotic stars and 82 CSs.In this CS group,there are 24 sources already classified as true close binary CSs in the literature.Hence,we discovered 58 new close binary CS candidates.This close binary(CB)sample represents more than half of what is currently available in the literature.In addition,we identified the radial velocities for 51 PNe.To our knowledge,24 of these were measured for the first time.The RV measurements predicted by Gaia,based on the Doppler shift of the CS absorption lines,and those derived from nebular emission lines,show satisfactory agreement except for a few extremely high-velocity PNe.展开更多
Planetary nebulae(PNe) are an important tool for studying the dynamics and chemical evolution of galaxies in the Local Universe, given their characteristic bright emission line spectra. The Andromeda Galaxy(M31) provi...Planetary nebulae(PNe) are an important tool for studying the dynamics and chemical evolution of galaxies in the Local Universe, given their characteristic bright emission line spectra. The Andromeda Galaxy(M31) provides a unique laboratory for studying PNe in the circumnuclear region,thanks to its proximity and almost uniformly low line-of-sight extinction that ensures observations with high resolution and sensitivity. Using the WIYN/Hydra multi-fiber spectrograph, we have obtained optical(4119–6882 A?) spectra of 77 PN candidates selected from Hubble Space Telescope narrow-band imaging, which are located within the central ~500 pc region of M31. Among these candidates, 49(64%) are spectroscopically observed for the first time. The spectra of 300 previously known PNe and H Ⅱ regions, which primarily reside in the disk, are also taken for comparison. All 77 circumnuclear PN candidates exhibit prominent emission lines, including [O Ⅲ] λ5007, [N Ⅱ] λ6583, Hα and Hβ,strongly suggesting that they are genuine PNe. We measured the line fluxes, radial velocities and line widths for all objects, and found that the radial velocities of the circumnuclear PNe generally trace rotation of the inner bulge. We also estimated a dynamical mass of ~6.4±0.5×10~9 M_⊙ enclosed within an effective galactocentric radius of 340 pc, which is compatible with the previously estimated total stellar mass in this region.展开更多
In our previous work on the 3-dimensional dynamical structure of planetary nebulae the effect of magnetic field was not considered. Recently Jordan et al. have directly detected magnetic fields in the central stars of...In our previous work on the 3-dimensional dynamical structure of planetary nebulae the effect of magnetic field was not considered. Recently Jordan et al. have directly detected magnetic fields in the central stars of some planetary nebulae. This discovery supports the hypothesis that the non-spherical shape of most planetary nebulae is caused by magnetic fields in AGB stars. In this study we focus on the role of initially weak toroidal magnetic fields embedded in a stellar wind in altering the shape of the PN. We found that magnetic pressure is probably influential on the observed shape of most PNe.展开更多
We address the physical and kinematical properties of Wolf–Rayet[WR]central stars(CSs)and their host planetary nebulae(PNe).The studied sample comprises all[WR]CSs that are currently known.The analysis is based on re...We address the physical and kinematical properties of Wolf–Rayet[WR]central stars(CSs)and their host planetary nebulae(PNe).The studied sample comprises all[WR]CSs that are currently known.The analysis is based on recent observations of the parallax,proper motion,and color index of[WR]CSs from the Gaia space mission’s early third release(eDR3)catalog,as well as common nebular characteristics.The results revealed an evolutionary sequence,in terms of decreasing Teff,from the early hot[WO 1]to the late cold[WC 12]stars.This evolutionary sequence extends beyond[WR]CS temperature and luminosity to additional CS and nebular characteristics.The statistical analysis shows that the mean final stellar mass and evolutionary age of the[WR]CS sample are 0.595±0.13M⊙and 9449±2437 yr,respectively,with a mean nebular dynamical age of 7270±1380 yr.In addition,we recognize that the color of the majority(∼85%)of[WR]CSs tends to be red rather than their genuine blue color.The analysis indicates that two-thirds of the apparent red color of most[WR]s is attributed to the interstellar extinction whereas the other one-third is due to the PN self-extinction effect.展开更多
I analyze a new X-ray image of the youngest supernova remnant(SNR)in the Galaxy,which is the type Ia SNR G1.9+0.3,and reveal a very clear point-symmetrical structure.Since explosion models of type Ia supernovae(SNe Ia...I analyze a new X-ray image of the youngest supernova remnant(SNR)in the Galaxy,which is the type Ia SNR G1.9+0.3,and reveal a very clear point-symmetrical structure.Since explosion models of type Ia supernovae(SNe Ia)do not form such morphologies,the point-symmetrical morphology must come from the circumstellar material(CSM)into which the ejecta expands.The large-scale point-symmetry that I identify and the known substantial deceleration of the ejecta of SNR G1.9+0.3 suggest a relatively massive CSM of■1M⊙.I argue that the most likely explanation is the explosion of this SN Ia into a planetary nebula.The scenario that predicts a large fraction of SN Ia inside PNe(SNIPs)is the core degenerate scenario.Other SN Ia scenarios might lead to only a very small fraction of SNIPs or none at all.展开更多
The present work aims to build a new statistical distance scale for planetary nebulae(PNe)based on a rigorous calibration sample.The distances of the calibration sample are derived from the trigonometric parallax meth...The present work aims to build a new statistical distance scale for planetary nebulae(PNe)based on a rigorous calibration sample.The distances of the calibration sample are derived from the trigonometric parallax method using the recent measurements of Gaia Early Data Release 3(Gaia EDR3).The new distance scale is created by applying the well-known linear relationship between the radio surface brightness temperature and the nebular radius.The calibration sample is made up of 96 PNe of accurately computed distances with uncertainties less than20%.Earlier ground-and space-based trigonometric parallaxes of PNe display inconsistency with those of Gaia,particularly the Hipparcos results.In addition,these measurements have appreciably lower precision than those of Gaia.When compared to the trigonometric technique,the expansion and kinematic methods exhibited more consistency than the spectroscopic,extinction,gravity,and photoionization methods.Furthermore,contrary to earlier results in the literature,the extinction and gravity methods,on average,underestimate and slightly overestimate the PN distances respectively.As a byproduct of extracting the Gaia parallaxes,we detect the radial velocity and variability for 14 and 3 PN central stars(CSs),respectively.To our knowledge,the variability of Hen 2-447 CS has been determined for the first time.展开更多
This article discusses the physical and kinematical characteristics of planetary nebulae accompanying PG 1159 central stars.The study is based on the parallax and proper motion measurements recently offered by the Gai...This article discusses the physical and kinematical characteristics of planetary nebulae accompanying PG 1159 central stars.The study is based on the parallax and proper motion measurements recently offered by the Gaia space mission.Two approaches were used to investigate the kinematical properties of the sample.The results revealed that most of the studied nebulae arise from progenitor stars in the mass range 0.9-1.75 M⊙.Furthermore,they tend to live within the Galactic thick disk and move with an average peculiar velocity of 61.7±19.2 km s^(-1) at a mean vertical height of 469±79 pc.The locations of the PG 1159 stars on the H-R diagram indicate that they have an average final stellar mass and evolutionary age of 0.58±0.08 M⊙and 25.5±5.3×103 yr,respectively.We found a good agreement between the mean evolutionary age of the PG 1159 stars and the mean dynamical age of their companion planetary nebulae(28.0±6.4×103 yr).展开更多
We report a multi-wavelength study of two evolved planetary nebulae(PNs)M 2–55 and Abell 2.Deep optical narrow-band images([O III],Hα,and[N II])of M 2–55 reveal two pairs of bipolar lobes and a new faint arc-like s...We report a multi-wavelength study of two evolved planetary nebulae(PNs)M 2–55 and Abell 2.Deep optical narrow-band images([O III],Hα,and[N II])of M 2–55 reveal two pairs of bipolar lobes and a new faint arc-like structure.This arc-shaped filament around M 2–55 appears as a well-defined boundary from southwest to southeast,strongly suggesting that this nebula is in interaction with its surrounding interstellar medium.From the imaging data of Wide-field Infrared Survey Explorer(WISE)all-sky survey,we discovered extensive mid-infrared halos around these PNs,which are approximately twice the size of their main nebulae seen in the visible.We also present a mid-resolution optical spectrum of M 2–55,which shows that it is a high-excitation evolved PN with a low electron density of 250 cm^-3.Furthermore,we investigate the properties of these nebulae from their spectral energy distributions(SEDs)by means of archival data.展开更多
Planetary Nebulae (PN) distances represent the fundamental parameter for the determination the physical properties of the central star of PN. In this paper the distances scale to Planetary Nebulae in the Galactic bulg...Planetary Nebulae (PN) distances represent the fundamental parameter for the determination the physical properties of the central star of PN. In this paper the distances scale to Planetary Nebulae in the Galactic bulge were calculated related to previous distances scales. The proposed distance scale was done by recalibrated the previous distance scale technique CKS/D82. This scale limited for nearby PN (D ≤ 3.5 kpc), so the surface fluxes less than other distance scales. With these criteria the results showed that the proposed distance scale is more accurate than other scales related to the observations for adopted sample of PN distances, also the limit of ionized radius (Rio) for all both optically thick and optically thin in the rang of sizes (0.45 > Rio (pc) > 0.03).展开更多
This article reviews the current works on ultra-compact double-degenerate binaries in the presence of magnetic interaction, in particular, unipolar induction. The orbital dynamics and evolution of compact white-dwarf ...This article reviews the current works on ultra-compact double-degenerate binaries in the presence of magnetic interaction, in particular, unipolar induction. The orbital dynamics and evolution of compact white-dwarf pairs are discussed in detail. Models and predictions of electron cyclotron masers from unipolar-inductor compact binaries and unipolar-inductor white-dwarf planetary systems are presented. Einstein-Laub effects in compact binaries are briefly discussed.展开更多
We report the results of CO(1-0) (J=l-0) observations for 20 selected planetary nebulae (PNe), using the 13.7 m radio telescope of Purple Mountain Observatory at the Qinghai Station. Due to weak CO(1-0) emission, long...We report the results of CO(1-0) (J=l-0) observations for 20 selected planetary nebulae (PNe), using the 13.7 m radio telescope of Purple Mountain Observatory at the Qinghai Station. Due to weak CO(1-0) emission, long integrated time observations have been carried out for most of sampled PNe. Among these PNe, nine are first detections in CO(1-0) named NGC 6445, Ml-59, M4-9, M2-51, M4-18, He2-459, Sh2-71, K3-31, M2-52, and one is the first possible detection named V-Vl-8, a probably misclassified PN. NGC 6445, Ml-59, M4-9 and M2-51 have been detected in CO(2-1)(J=2-1). Although having been observed in previous CO surveys, Sh2-71 and M4-18 were not detected in CO; M2-52, K3-31, He2-459 are the first detected PNe in CO emission and V-Vl-8 is given with a first completed spectrum detected in CO(1-0). Comparing these data with other previous observational ones, we discuss the relationships between CO(1-0) emission and evolution of PNe: While the nebular radii increase, the CO(l-0) line integrated intensities multiplied by distances have a decreasing trend. Also the masses of molecular envelopes (from 0.001 to 1 M⊙) for PNe are decreased with increasing nebular radii. All the results mean the CO(1-0) emission decreases dramatically with the nebular evolution. The detectability of CO restricted by different PNe which have different dust properties and different evolutionary stages is also analyzed.展开更多
Planetary nebulae are the progenetors of white dwarfs in the final evolution stage of stars with intermediate initial mass ( 1M_⊙【M_*【9M_⊙). The planetary nebulae can be devided into different groups according to ...Planetary nebulae are the progenetors of white dwarfs in the final evolution stage of stars with intermediate initial mass ( 1M_⊙【M_*【9M_⊙). The planetary nebulae can be devided into different groups according to the spectral type of their core stars. One of these groups, in which the spectrum is dominated by the carbon lines of different levels of ionization, is similar to the carbon-rich Wolf-Rayet stars. According to Van der Hucht展开更多
With the increasing number of detected exoplanet samples, the statistical properties of planetary systems have become much clearer. In this review, we sum- marize the major statistical results that have been revealed ...With the increasing number of detected exoplanet samples, the statistical properties of planetary systems have become much clearer. In this review, we sum- marize the major statistical results that have been revealed mainly by radial velocity and transiting observations, and try to interpret them within the scope of the classical core-accretion scenario of planet formation, especially in the formation of different orbital architectures for planetary systems around main sequence stars. Based on the different possible formation routes for different planet systems, we tentatively classify them into three major catalogs： hot Jupiter systems, standard systems and distant giant planet systems. The standard systems can be further categorized into three sub-types under different circumstances： solar-like systems, hot Super-Earth systems, and sub- giant planet systems. We also review the theory of planet detection and formation in binary systems as well as planets in star clusters.展开更多
Since Sep.2018,LAMOST has started the medium-resolution(R~7500)spectral survey(MRS).We proposed the spectral survey of Galactic nebulae,including HⅡregions,HH objects,supernova remnants,planetary nebulae and the spec...Since Sep.2018,LAMOST has started the medium-resolution(R~7500)spectral survey(MRS).We proposed the spectral survey of Galactic nebulae,including HⅡregions,HH objects,supernova remnants,planetary nebulae and the special stars with MRS(LAMOST MRS-N).LAMOST MRS-N covers about 1700 square degrees of the northern Galactic plane within 40°<l<215°and-5°<b<5°.In this 5-year survey,we plan to observe about 500 thousand nebulae spectra.According to the commissioning observations,the nebulae spectra can provide precise radial velocity with uncertainty less than 1 km s^(-1).These high-precision spectral data are of great significance to our understanding of star formation and evolution.展开更多
We present the dependence of electron temperature fluctuations of O++ and H+ by the chemical abundances of oxygen and nitrogen. Models assume that hydrogen density is uniform in one case and non uniform in the second ...We present the dependence of electron temperature fluctuations of O++ and H+ by the chemical abundances of oxygen and nitrogen. Models assume that hydrogen density is uniform in one case and non uniform in the second case, which vary with the distance from the central star. The abundances of oxygen and nitrogen change by scale factor 5 and 1/5. Our analysis suggests that temperature fluctuations are consistent with photoionization. Using the cloudy photoionization code, we found a reasonable close agreement of the computed value with the one that was done before this work. Our simulation also shows that how change of abundances affects temperature fluctuations and its value is less than 0.01.展开更多
In current photoionization models, determination of the ionization structure of the nebulae is a crucial part of the calculations for non-uniform hydrogen density. We have been tried to compute temperature fluctuation...In current photoionization models, determination of the ionization structure of the nebulae is a crucial part of the calculations for non-uniform hydrogen density. We have been tried to compute temperature fluctuations of electron and electron density by changing hydrogen density by scale factor of 10 at high temperature of blackbody. We have studied the ionization structure of hydrogen and helium by means of cloudy C13.01 codes. We find a reasonable close agreement of the computed value. Moreover, the ionization structure of oxygen at ionization stages of, O I - O IV, in gaseous nebulae are studied by changing non uniform hydrogen density with power law. Our simulation also shows that how the change of this density affect temperature fluctuations, electron density and ionization structures of oxygen, helium and hydrogen with and without grains. The result also shows the impact of the forbidden lines of [O III] and [O II] to cool down the temperature of electron.展开更多
I examine images of 50 planetary nebulae(PNe)with observable post-common envelope evolution(CEE)binary central stars and find that jets are about 40%more common than dense equatorial outflows.Because,in some cases,ene...I examine images of 50 planetary nebulae(PNe)with observable post-common envelope evolution(CEE)binary central stars and find that jets are about 40%more common than dense equatorial outflows.Because,in some cases,energetic jets can compress an equatorial outflow and because fast jets might disperse early in the PN evolution and avoid detection,the CEE process is likelier to launch jets than to eject a dense equatorial outflow by a larger factor than 1.4.In most cases,the companion,mainly a main sequence star,launches the jets as it accretes mass from the envelope of the giant star.By CEE jets,I also refer to jets launched shortly before the onset of the CEE,likely a grazing envelope evolution phase,and shortly after the CEE.The jets and the accretion of mass by the companion before,during,and after the CEE affect envelope mass removal and the final orbital separation.Most numerical simulations of the CEE ignore jets,and those that include jets omit other processes.Despite the considerable progress in the last decade with tens of hydrodynamical simulations of the CEE,we are still far from correctly simulating the CEE.Including jets in simulations of the CEE requires heavy computer resources,but it must be the next step.展开更多
文摘Using the stellar evolution code MESA,we mimic the negative jet feedback mechanism in common envelope evolution(CEE)of low-mass main sequence stars,M_(2)?0.1-0.2M_(☉),spiraling inward inside the envelopes of asymptotic giant branch or red giant branch stars and find that the jets reduced the envelope density,and therefore the jets'power,by a factor ofχ≈0.5(M_(2)/0.1M_(☉))^(-1).We mimic the energy that the jets deposit into the envelope by depositing energy into the outer envelope,a process that inflates the envelope,therefore reducing the density in the vicinity of the main sequence star,the accretion rate,and the jets'power.In deriving this expression for the negative jet feedback coefficientχ,we assume that the actual mass accretion rate is a fractionξ≈0.2-0.5 of the classical Bondi-Hoyle-Lyttleton mass accretion rate and that the jets carry a fractionη≈0.25-0.5 of the accretion energy onto the main sequence star.Our study is another step in establishing the major role of jets in the onset and early phase of CEE,a possible grazing envelope evolution phase,and in transient events,such as luminous red novae,which these processes can power.
基金the JSPS KAKENHI program(JP16H02167)support from the ARC Discovery project DP180101061 of the Australian Government+1 种基金the CAS LCWR Program(2018-XBQNXZB-021)of Chinathe Japanese MEXT scholarship,the Leids Kerkhoven-Bosscha Fonds(LKBF17.0.002)。
文摘The subclass of bipolar Planetary Nebulae(PNe)exhibits well-defined low-power outflows and some shows shock-related equatorial spiderweb structures and hourglass structures surrounding these outflows.These structures are distinctly different from the phenomena associated with spherical and elliptical PNe and suggest a non-standard way to simultaneously energise both kinds of structures.This paper presents evidence from the published literature on bipolar PN Hb 12 and other sources in support of an alternative scenario for energising these structures by means of accretion from material shells deposited during earlier post-AGB and pre-PNe evolutionary stages.In addition to energising the bipolar outflow,a sub-Eddington accretion scenario could hydrodynamically explain the spiderweb and outer hourglass structures as oblique shockwaves for guiding the accreting material into the equatorial region of the source.Estimates of the accretion rate resulting from fallback-related spherical accretion could indeed help to drive a low-power outflow and contribute to the total luminosity of these sources.
基金The Guoshoujing Telescope(GSJT)is a National Major Scientific Project built by the Chinese Academy of SciencesFunding for the project has been provided by the National Development and Reform Commission
文摘Planetary nebulae （PNe） are good tracers of the stellar populations, chemical composition and dynamics of their host galaxies. This paper reports the discovery of new PNe in the outskirts of the Andromeda Galaxy （M31） with the Guoshoujing Telescope （GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope-LAMOST） during its early commissioning phase. In total, 36 candidates selected from SDSS photometry are confirmed in terms of their PN nature, including 17 new discoveries and another 19 previously known emission line objects. Their positions, spectra, radial velocities and m5007 magnitudes are presented. We discuss the potential for detecting more PNe in M 31 with GSJT＇s multi-object spectroscopy and the related applications in studies of the dynamics and chemistry of M 31 and its assemblage history.
文摘The extremely accurate estimates of stellar variability and radial velocity in the Gaia Data Release 3(Gaia DR3)have enabled us to examine the close binarity and radial velocity(RV)of central stars(CSs)of planetary nebulae(PNe).This study is twofold:(1)searching for new close binary CS candidates to better understand how binarity affects the formation and evolution of PNe;and(2)extending the sample size of known RVs of PNe in order to understand their kinematics and the dynamics of the Milky Way.As a target sample,we used all true,possible,and likely PNe available in the literature.Then,we looked for their matched Gaia DR3 sources that provide measurements of variability and RV.As a result,we detected the first large collection of trustworthy photometric variability of 26 symbiotic stars and 82 CSs.In this CS group,there are 24 sources already classified as true close binary CSs in the literature.Hence,we discovered 58 new close binary CS candidates.This close binary(CB)sample represents more than half of what is currently available in the literature.In addition,we identified the radial velocities for 51 PNe.To our knowledge,24 of these were measured for the first time.The RV measurements predicted by Gaia,based on the Doppler shift of the CS absorption lines,and those derived from nebular emission lines,show satisfactory agreement except for a few extremely high-velocity PNe.
基金supported by the National Key Research and Development Program of China(No.2017YFA0402703)the National Natural Science Foundation of China(Grant No.11133001)+1 种基金support from the Recruitment Program of Global Youth Expertsfunding support from the European Research Council under the European Union’s Seventh Framework Programme(FP7/2007-2013)/ERC grant agreement n~⊙[614922]
文摘Planetary nebulae(PNe) are an important tool for studying the dynamics and chemical evolution of galaxies in the Local Universe, given their characteristic bright emission line spectra. The Andromeda Galaxy(M31) provides a unique laboratory for studying PNe in the circumnuclear region,thanks to its proximity and almost uniformly low line-of-sight extinction that ensures observations with high resolution and sensitivity. Using the WIYN/Hydra multi-fiber spectrograph, we have obtained optical(4119–6882 A?) spectra of 77 PN candidates selected from Hubble Space Telescope narrow-band imaging, which are located within the central ~500 pc region of M31. Among these candidates, 49(64%) are spectroscopically observed for the first time. The spectra of 300 previously known PNe and H Ⅱ regions, which primarily reside in the disk, are also taken for comparison. All 77 circumnuclear PN candidates exhibit prominent emission lines, including [O Ⅲ] λ5007, [N Ⅱ] λ6583, Hα and Hβ,strongly suggesting that they are genuine PNe. We measured the line fluxes, radial velocities and line widths for all objects, and found that the radial velocities of the circumnuclear PNe generally trace rotation of the inner bulge. We also estimated a dynamical mass of ~6.4±0.5×10~9 M_⊙ enclosed within an effective galactocentric radius of 340 pc, which is compatible with the previously estimated total stellar mass in this region.
文摘In our previous work on the 3-dimensional dynamical structure of planetary nebulae the effect of magnetic field was not considered. Recently Jordan et al. have directly detected magnetic fields in the central stars of some planetary nebulae. This discovery supports the hypothesis that the non-spherical shape of most planetary nebulae is caused by magnetic fields in AGB stars. In this study we focus on the role of initially weak toroidal magnetic fields embedded in a stellar wind in altering the shape of the PN. We found that magnetic pressure is probably influential on the observed shape of most PNe.
基金the European Space Agency(ESA)mission Gaia,processed by the Gaia Data Processing and Analysis Consortium(DPAC).This research has made use of the SIMBAD database,operated at CDS,Strasbourg,France.
文摘We address the physical and kinematical properties of Wolf–Rayet[WR]central stars(CSs)and their host planetary nebulae(PNe).The studied sample comprises all[WR]CSs that are currently known.The analysis is based on recent observations of the parallax,proper motion,and color index of[WR]CSs from the Gaia space mission’s early third release(eDR3)catalog,as well as common nebular characteristics.The results revealed an evolutionary sequence,in terms of decreasing Teff,from the early hot[WO 1]to the late cold[WC 12]stars.This evolutionary sequence extends beyond[WR]CS temperature and luminosity to additional CS and nebular characteristics.The statistical analysis shows that the mean final stellar mass and evolutionary age of the[WR]CS sample are 0.595±0.13M⊙and 9449±2437 yr,respectively,with a mean nebular dynamical age of 7270±1380 yr.In addition,we recognize that the color of the majority(∼85%)of[WR]CSs tends to be red rather than their genuine blue color.The analysis indicates that two-thirds of the apparent red color of most[WR]s is attributed to the interstellar extinction whereas the other one-third is due to the PN self-extinction effect.
基金supported by a grant from the Israel Science Foundation(769/20)。
文摘I analyze a new X-ray image of the youngest supernova remnant(SNR)in the Galaxy,which is the type Ia SNR G1.9+0.3,and reveal a very clear point-symmetrical structure.Since explosion models of type Ia supernovae(SNe Ia)do not form such morphologies,the point-symmetrical morphology must come from the circumstellar material(CSM)into which the ejecta expands.The large-scale point-symmetry that I identify and the known substantial deceleration of the ejecta of SNR G1.9+0.3 suggest a relatively massive CSM of■1M⊙.I argue that the most likely explanation is the explosion of this SN Ia into a planetary nebula.The scenario that predicts a large fraction of SN Ia inside PNe(SNIPs)is the core degenerate scenario.Other SN Ia scenarios might lead to only a very small fraction of SNIPs or none at all.
文摘The present work aims to build a new statistical distance scale for planetary nebulae(PNe)based on a rigorous calibration sample.The distances of the calibration sample are derived from the trigonometric parallax method using the recent measurements of Gaia Early Data Release 3(Gaia EDR3).The new distance scale is created by applying the well-known linear relationship between the radio surface brightness temperature and the nebular radius.The calibration sample is made up of 96 PNe of accurately computed distances with uncertainties less than20%.Earlier ground-and space-based trigonometric parallaxes of PNe display inconsistency with those of Gaia,particularly the Hipparcos results.In addition,these measurements have appreciably lower precision than those of Gaia.When compared to the trigonometric technique,the expansion and kinematic methods exhibited more consistency than the spectroscopic,extinction,gravity,and photoionization methods.Furthermore,contrary to earlier results in the literature,the extinction and gravity methods,on average,underestimate and slightly overestimate the PN distances respectively.As a byproduct of extracting the Gaia parallaxes,we detect the radial velocity and variability for 14 and 3 PN central stars(CSs),respectively.To our knowledge,the variability of Hen 2-447 CS has been determined for the first time.
文摘This article discusses the physical and kinematical characteristics of planetary nebulae accompanying PG 1159 central stars.The study is based on the parallax and proper motion measurements recently offered by the Gaia space mission.Two approaches were used to investigate the kinematical properties of the sample.The results revealed that most of the studied nebulae arise from progenitor stars in the mass range 0.9-1.75 M⊙.Furthermore,they tend to live within the Galactic thick disk and move with an average peculiar velocity of 61.7±19.2 km s^(-1) at a mean vertical height of 469±79 pc.The locations of the PG 1159 stars on the H-R diagram indicate that they have an average final stellar mass and evolutionary age of 0.58±0.08 M⊙and 25.5±5.3×103 yr,respectively.We found a good agreement between the mean evolutionary age of the PG 1159 stars and the mean dynamical age of their companion planetary nebulae(28.0±6.4×103 yr).
基金supported by MoST grant(108-2112-M-008-001)support of the staff of the Lijiang 2.4m telescope+4 种基金Funding for the telescope has been provided by Chinese Academy of Sciences and the People’s Government of Yunnan ProvinceFinancial support for this work is supported by the grants from The Science and Technology Development Fund,Macao SAR(file no061/2017/A2and 0007/2019/A)the Faculty Research Grants of Macao University of Science and Technology(project codeFRG-19-004-SSI)supported by the National Natural Science Foundation of China(NSFC,Grant No.U1731122)NSFC(Grant No.11973099)for financial support
文摘We report a multi-wavelength study of two evolved planetary nebulae(PNs)M 2–55 and Abell 2.Deep optical narrow-band images([O III],Hα,and[N II])of M 2–55 reveal two pairs of bipolar lobes and a new faint arc-like structure.This arc-shaped filament around M 2–55 appears as a well-defined boundary from southwest to southeast,strongly suggesting that this nebula is in interaction with its surrounding interstellar medium.From the imaging data of Wide-field Infrared Survey Explorer(WISE)all-sky survey,we discovered extensive mid-infrared halos around these PNs,which are approximately twice the size of their main nebulae seen in the visible.We also present a mid-resolution optical spectrum of M 2–55,which shows that it is a high-excitation evolved PN with a low electron density of 250 cm^-3.Furthermore,we investigate the properties of these nebulae from their spectral energy distributions(SEDs)by means of archival data.
文摘Planetary Nebulae (PN) distances represent the fundamental parameter for the determination the physical properties of the central star of PN. In this paper the distances scale to Planetary Nebulae in the Galactic bulge were calculated related to previous distances scales. The proposed distance scale was done by recalibrated the previous distance scale technique CKS/D82. This scale limited for nearby PN (D ≤ 3.5 kpc), so the surface fluxes less than other distance scales. With these criteria the results showed that the proposed distance scale is more accurate than other scales related to the observations for adopted sample of PN distances, also the limit of ionized radius (Rio) for all both optically thick and optically thin in the rang of sizes (0.45 > Rio (pc) > 0.03).
文摘This article reviews the current works on ultra-compact double-degenerate binaries in the presence of magnetic interaction, in particular, unipolar induction. The orbital dynamics and evolution of compact white-dwarf pairs are discussed in detail. Models and predictions of electron cyclotron masers from unipolar-inductor compact binaries and unipolar-inductor white-dwarf planetary systems are presented. Einstein-Laub effects in compact binaries are briefly discussed.
基金We would like to thank the operators and staff of the 13.7m telescope of Purple Mountain Observatory at the Qinghai Station for their support.This work was supported by the National Natural Science Foundation of China(Grant No.19873003)and United Laborat
文摘We report the results of CO(1-0) (J=l-0) observations for 20 selected planetary nebulae (PNe), using the 13.7 m radio telescope of Purple Mountain Observatory at the Qinghai Station. Due to weak CO(1-0) emission, long integrated time observations have been carried out for most of sampled PNe. Among these PNe, nine are first detections in CO(1-0) named NGC 6445, Ml-59, M4-9, M2-51, M4-18, He2-459, Sh2-71, K3-31, M2-52, and one is the first possible detection named V-Vl-8, a probably misclassified PN. NGC 6445, Ml-59, M4-9 and M2-51 have been detected in CO(2-1)(J=2-1). Although having been observed in previous CO surveys, Sh2-71 and M4-18 were not detected in CO; M2-52, K3-31, He2-459 are the first detected PNe in CO emission and V-Vl-8 is given with a first completed spectrum detected in CO(1-0). Comparing these data with other previous observational ones, we discuss the relationships between CO(1-0) emission and evolution of PNe: While the nebular radii increase, the CO(l-0) line integrated intensities multiplied by distances have a decreasing trend. Also the masses of molecular envelopes (from 0.001 to 1 M⊙) for PNe are decreased with increasing nebular radii. All the results mean the CO(1-0) emission decreases dramatically with the nebular evolution. The detectability of CO restricted by different PNe which have different dust properties and different evolutionary stages is also analyzed.
文摘Planetary nebulae are the progenetors of white dwarfs in the final evolution stage of stars with intermediate initial mass ( 1M_⊙【M_*【9M_⊙). The planetary nebulae can be devided into different groups according to the spectral type of their core stars. One of these groups, in which the spectrum is dominated by the carbon lines of different levels of ionization, is similar to the carbon-rich Wolf-Rayet stars. According to Van der Hucht
基金supported by the National Natural Science Foundation of China (Nos. 10833001, 10925313, 11078001 and 11003010)Fundamental Research Funds for the Central Universities (No. 1112020102)the Research Fund for the Doctoral Program of Higher Education of China (Nos. 20090091110002 and 20090091120025)
文摘With the increasing number of detected exoplanet samples, the statistical properties of planetary systems have become much clearer. In this review, we sum- marize the major statistical results that have been revealed mainly by radial velocity and transiting observations, and try to interpret them within the scope of the classical core-accretion scenario of planet formation, especially in the formation of different orbital architectures for planetary systems around main sequence stars. Based on the different possible formation routes for different planet systems, we tentatively classify them into three major catalogs： hot Jupiter systems, standard systems and distant giant planet systems. The standard systems can be further categorized into three sub-types under different circumstances： solar-like systems, hot Super-Earth systems, and sub- giant planet systems. We also review the theory of planet detection and formation in binary systems as well as planets in star clusters.
基金supported by the National Natural Science Foundation of China(Grant Nos.12073051,12090040,12090041,11733006,11403061,11903048,U1631131,11973060,12090044,12073039,11633009,U1531118,11403037,11225316,11173030,11303038,Y613991N01,U1531245,11833006)the Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciences+4 种基金the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDY-SSW-SLH007)the supports from the Science and Technology Development Fund,Macao SAR(file No.0007/2019/A)Faculty Research Grants of the Macao University of Science and Technology(No.FRG19-004-SSI)a National Major Scientific Project built by the Chinese Academy of SciencesFunding for the project has been provided by the National Development and Reform Commission。
文摘Since Sep.2018,LAMOST has started the medium-resolution(R~7500)spectral survey(MRS).We proposed the spectral survey of Galactic nebulae,including HⅡregions,HH objects,supernova remnants,planetary nebulae and the special stars with MRS(LAMOST MRS-N).LAMOST MRS-N covers about 1700 square degrees of the northern Galactic plane within 40°<l<215°and-5°<b<5°.In this 5-year survey,we plan to observe about 500 thousand nebulae spectra.According to the commissioning observations,the nebulae spectra can provide precise radial velocity with uncertainty less than 1 km s^(-1).These high-precision spectral data are of great significance to our understanding of star formation and evolution.
文摘We present the dependence of electron temperature fluctuations of O++ and H+ by the chemical abundances of oxygen and nitrogen. Models assume that hydrogen density is uniform in one case and non uniform in the second case, which vary with the distance from the central star. The abundances of oxygen and nitrogen change by scale factor 5 and 1/5. Our analysis suggests that temperature fluctuations are consistent with photoionization. Using the cloudy photoionization code, we found a reasonable close agreement of the computed value with the one that was done before this work. Our simulation also shows that how change of abundances affects temperature fluctuations and its value is less than 0.01.
文摘In current photoionization models, determination of the ionization structure of the nebulae is a crucial part of the calculations for non-uniform hydrogen density. We have been tried to compute temperature fluctuations of electron and electron density by changing hydrogen density by scale factor of 10 at high temperature of blackbody. We have studied the ionization structure of hydrogen and helium by means of cloudy C13.01 codes. We find a reasonable close agreement of the computed value. Moreover, the ionization structure of oxygen at ionization stages of, O I - O IV, in gaseous nebulae are studied by changing non uniform hydrogen density with power law. Our simulation also shows that how the change of this density affect temperature fluctuations, electron density and ionization structures of oxygen, helium and hydrogen with and without grains. The result also shows the impact of the forbidden lines of [O III] and [O II] to cool down the temperature of electron.
文摘I examine images of 50 planetary nebulae(PNe)with observable post-common envelope evolution(CEE)binary central stars and find that jets are about 40%more common than dense equatorial outflows.Because,in some cases,energetic jets can compress an equatorial outflow and because fast jets might disperse early in the PN evolution and avoid detection,the CEE process is likelier to launch jets than to eject a dense equatorial outflow by a larger factor than 1.4.In most cases,the companion,mainly a main sequence star,launches the jets as it accretes mass from the envelope of the giant star.By CEE jets,I also refer to jets launched shortly before the onset of the CEE,likely a grazing envelope evolution phase,and shortly after the CEE.The jets and the accretion of mass by the companion before,during,and after the CEE affect envelope mass removal and the final orbital separation.Most numerical simulations of the CEE ignore jets,and those that include jets omit other processes.Despite the considerable progress in the last decade with tens of hydrodynamical simulations of the CEE,we are still far from correctly simulating the CEE.Including jets in simulations of the CEE requires heavy computer resources,but it must be the next step.
