Study of Complex Nitrogen and Oxygen-bearing Molecules toward the High-mass Protostar IRAS 18089–1732

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.

The ALMA-QUARKS Survey.Ⅱ.The ACA 1.3 mm Continuum Source Catalog and the Assembly of Dense Gas in Massive Star-Forming Clumps

Leveraging the high resolution,sensitivity,and wide frequency coverage of the Atacama Large Millimeter/submillimeter Array(ALMA),the QUARKS survey,standing for“Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures”,is observing 139 massive starforming clumps at ALMA Band 6(λ~1.3 mm).This paper introduces the Atacama Compact Array(ACA)7 m data of the QUARKS survey,describing the ACA observations and data reduction.Combining multiwavelength data,we provide the first edition of QUARKS atlas,offering insights into the multiscale and multiphase interstellar medium in high-mass star formation.The ACA 1.3 mm catalog includes 207 continuum sources that are called ACA sources.Their gas kinetic temperatures are estimated using three formaldehyde transitions with a non-LTE radiation transfer model,and the mass and density are derived from a dust emission model.The ACA sources are massive(16–84 percentile values of 6–160 M_(⊙)),gravity-dominated(M∝R^(1.1))fragments within massive clumps,with supersonic turbulence(M>1)and embedded star-forming protoclusters.We find a linear correlation between the masses of the fragments and the massive clumps,with a ratio of 6%between the two.When considering fragments as representative of dense gas,the ratio indicates a dense gas fraction(DGF)of 6%,although with a wide scatter ranging from 1%to 10%.If we consider the QUARKS massive clumps to be what is observed at various scales,then the size-independent DGF indicates a self-similar fragmentation or collapsing mode in protocluster formation.With the ACA data over four orders of magnitude of luminosity-to-mass ratio(L/M),we find that the DGF increases significantly with L/M,which indicates clump evolutionary stage.We observed a limited fragmentation at the subclump scale,which can be explained by a dynamic global collapse process.

What is the Role of Gravity,Turbulence and Magnetic Fields in High-mass Star Formation Clouds?

To explore the potential role of gravity,turbulence and magnetic fields in high-mass star formation in molecular clouds,this study revisits the velocity dispersion–size(σ–L)and density–size(ρ–L)scalings and the associated turbulent energy spectrum using an extensive data sample.The sample includes various hierarchical density structures in high-mass star formation clouds,across scales of 0.01–100 pc.We observeσ∝L^(0.26)andρ∝L^(-1.54)scalings,converging toward a virial equilibrium state.A nearly flat virial parameter–mass(α_(vir)-M)distribution is seen across all density scales,withα_(vir)values centered around unity,suggesting a global equilibrium maintained by the interplay between gravity and turbulence across multiple scales.Our turbulent energy spectrum(E(k))analysis,based on theσ–L andρ–L scalings,yields a characteristic E(k)∝k^(-1.52).These findings indicate the potential significance of gravity,turbulence,and possibly magnetic fields in regulating dynamics of molecular clouds and high-mass star formation therein.

Mapping the emission line strengths and kinematics of supernova remnant S147 with extensive LAMOST spectroscopic observations

We present extensive spectroscopic observations of supernova remnant （SNR） S 147 collected with the Large sky Area Multi-Object fiber Spectroscopic Telescope （LAMOST）. The spectra were care- fully sky-subtracted taking into account the complex filamentary structure of S 147. We have utilized all available LAMOST spectra toward S 147, including sky and stellar spectra. By measuring the prominent optical emission lines including Ha, [NII] ）λ 6584 and [S n] λλ6717, 6731, we present maps of radial velocity and line intensity ratio covering the whole nebula of S 147 with unprecedented detail. The maps spatially correlate well with the complex filamentary structure of S147. For the central 2° of S147, the radial velocity varies from - 100 to 100 krn s^-1 and has peaks between - 0 and 10 km s^-1. The intensity ratios of Hα/[S n）λλ6717,6731, [Sn] λ 6717/λ 6731 and Ha/IN Hα/λ 6584 peak at about 0.77, 1.35 and 1.48, respectively, with a scatter of 0.17, 0.19 and 0.37, respectively. The intensity ratios are consistent with the literature values. However, the range of variations of line intensity ratios estimated here, which are representative of the whole nebula, is larger than previously estimated.

Hawking radiation and thermodynamics of a Vaidya-Bonner black hole

Using Parikh＇s tunneling method, the Hawking radiation on the apparent horizon of a Vaidya-Bonner black hole is calculated. When the back-reaction of particles is neglected, the thermal spectrum can be precisely obtained. Then, the black hole thermodynamics can be calculated successfully on the apparent horizon. When a relativistic perturbation is applied to the apparent horizon, a similar calculation can also lead to a purely thermal spectrum. The first law of thermodynamics can also be derived successfully at the new supersurface near the apparent horizon. When the event horizon is thought of as a deviation from the apparent horizon, the expressions of the characteristic position and temperature are consistent with the previous viewpoint which asserts that the thermodynamics should be based on the event horizon. It is concluded that the thermodynamics should be constructed exactly on the apparent horizon while the event horizon thermodynamics is just one of the perturbations near the apparent horizon.

Speckle-interferometric Study of Close Visual Binary System HIP 11253(HD 14874)using Gaia(DR2 and EDR3)

We present a comprehensive set of physical and geometrical parameters for each of the components of the close visual binary system HIP 11253(HD 14874).We present an analysis for the binary and multiple stellar systems with the aim to obtain a match between the overall observational spectral energy distribution of the system and the spectral synthesis created from model atmospheres using Al-Wardat's method for analyzing binary and multiple stellar systems.The epoch positions are used to determine the orbital parameters and the total mass.The parameters of both components are derived as:T_(eff)^(a)=6025,T_(eff)^(b)=4710,logg_(a)=4.55,logg_(b)=4.60,R_(a)=1.125 R_(⊙),R_(b)=0.88R_(⊙),L_(a)=1.849 L_(⊙),L_(b)=0.342 L_(⊙).Our analysis shows that the spectral types of the components are F9 and K3.By combining the orbital solution with the parallax measurements of Gaia DR2 and EDR3,we estimate the individual masses using the H-R diagram as M_(a)=1.09 M_(⊙)and M_(b)=0.59 M_(⊙)for using Gaia DR2 parallax and M_(a)=1.10 M_(⊙)and M_(b)=0.61 M_(⊙)for using Gaia EDR3 parallax.Finally,the location of both system's components on the stellar evolutionary tracks is presented.

Gas emission and dynamics in the infrared dark cloud G31.23＋0.05

We performed a multiwavelength study towards the infrared dark cloud （IRDC） G31.23＋0.05 with new CO observations from Purple Mountain Observatory and archival data （the GLIMPSE, MIPSGAL, HERSCHEL, ATLASGAL, BGPS and NVSS surveys）. From these observations, we iden- tified three IRDCs with systemic velocities of 108.36 ± 0.06 （cloud A）, 104.22 ± 0.11 （cloud B） and 75.73 ± 0.07 km s-1 （cloud C） in the line of sight towards IRDC G31.23. Analyses of the molecular and dust emission suggest that cloud A is a filamentary structure containing a young stellar object; clouds B and C both include a starless core. Clouds A and B are gravitationally bound and have a chance to form stars. In addition, the velocity information and the position-velocity diagram suggest that clouds A and B are adjacent in space and provide a clue hinting at a possible cloud-cloud collision. Additionally, the distribution of dust temperature shows a temperature bubble. The compact core in cloud A is associated with an UCHII region, an IRAS source, H20 masers, CH3OH masers and OH masers, suggesting that massive star formation is active there. We estimate the age of the HII region to be （0.03-0.09）Myr, indicating that the star inside is young.

Attitude dynamics and control of spacecraft using geomagnetic Lorentz force

Attitude stabilization of a charged rigid spacecraft in Low Earth Orbit using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth’s magnetic field will be subject to perturbations from the Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft’s orientation. We assume that the spacecraft is moving in the Earth’s magnetic field in an elliptical orbit under the effects of gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole.A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to mass ratio（α＊）. Stable orbits are identified for various values of α＊. The main parameters for stabilization of the spacecraft are α＊and the difference between the components of the moment of inertia for the spacecraft.

The bar and spiral arms in the Milky Way: structure and kinematics

The Milky Way is a spiral galaxy with the Schechter characteristic luminosity L*,thus an important anchor point of the Hubble sequence of all spiral galaxies.Yet the true appearance of the Milky Way has remained elusive for centuries.We review the current best understanding of the structure and kinematics of our home galaxy,and present an updated scientifically accurate visualization of the Milky Way structure with almost all components of the spiral arms,along with the COBE image in the solar perspective.The Milky Way contains a strong bar,four major spiral arms,and an additional arm segment(the Local arm)that may be longer than previously thought.The Galactic boxy bulge that we observe is mostly the peanut-shaped central bar viewed nearly end-on with a bar angle of^25°-30°from the SunGalactic center line.The bar transitions smoothly from a central peanut-shaped structure to an extended thin part that ends around R^5 kpc.The Galactic bulge/bar contains^30%-40%of the total stellar mass in the Galaxy.Dynamical modelling of both the stellar and gas kinematics yields a bar pattern rotation speed of^35-40 km s-1 kpc-1,corresponding to a bar rotation period of^160-180 Myr.From a galaxy formation point of view,our Milky Way is probably a pure-disk galaxy with little room for a significant merger-made,"classical"spheroidal bulge,and we give a number of reasons why this is the case.

Constraining Mass of M31 Combing Kinematics of Stars,Planetary Nebulae and Globular clusters

We construct a multiple-population discrete axisymmetric Jeans model for the Andromeda(M31)galaxy,considering three populations of kinematic tracers:48 supergiants and 721 planetary nebulae(PNe)in the bulge and disk regions,554 globular clusters extending to~30 kpc,and halo stars extending to~150 kpc of the galaxy.The three populations of tracers are organized in the same gravitational potential,while each population is allowed to have its own spatial distribution,rotation,and internal velocity anisotropy.The gravitational potential is a combination of stellar mass and a generalized NFW dark matter halo.We created two sets of models,one with a cusped dark matter halo and one with a cored dark matter halo.Both the cusped and cored model fit kinematics of all the three populations well,but the cored model is not preferred due to a too high concentration compared to that predicted from cosmological simulations.With a cusped dark matter halo,we obtained total stellar mass of 1.0±0.1×10^(11)M_(☉),dark matter halo virial mass of M_(200)=7.0±0.9×10^(11)M_(☉),virial radius of r_(200)=184±4 kpc,and concentration of c=20±4.The mass of M31 we obtained is at the lower side of the allowed ranges in the literature and consistent with the previous results obtained from the HⅠrotation curve and PNe kinematics.Velocity dispersion profile of the outer stellar halo is important in constraining the total mass while it is still largely uncertain.Further proper motion of bright sources from Gaia or the Chinese Space Station Telescope might help on improving the data and lead to stronger constraints on the total mass of M31.

Merger Dynamics of the Pair of Galaxy Clusters-A399 and A401

Convincing evidence for a past interaction between the two rich clusters A399 and A401 was recently found in the X-ray imaging observations. We examine the structure and dynamics of this pair of galaxy clusters. A mixture-modeling algorithm was applied to obtain a robust partition into two clusters, which allowed us to discuss the virial mass and velocity distribution of each cluster. Assuming that these two clusters follow a linear orbit and they have once experienced a close encounter, we model the binary cluster as a two-body system. As a result, four gravitationally bound solutions are obtained. The recent X-ray observations seem to favor a scenario in which the two clusters with a true separation of 5.4h-1 Mpc are currently expanding at 583 km s-1 along a direction with a projection angle of 67.5°, and they will reach a maximum extent of 5.65 h-1 Mpc in about 1.0 h-1 Gyr.

Kinematics of solar neighborhood stars and its dependence on age and metallicity

We have constructed a catalog containing the best available astrometric, photometric, radial velocity and astrophysical data for mainly F-type and G-type stars （called the Astrometric Catalog associated with Astrophysical Data, ACAD）. This contains 27 553 records and is used for the purpose of analyzing stellar kinematics in the solar neighborhood. Using the Lindblad-Oort model and compiled ACAD, we calculated the solar motion and Oort constants in different age-metallicity bins. The evolution of kinematical parameters with stellar age and metallicity was investigated directly. The results show that the component of the solar motion in the direction of Galactic rotation （denoted S_2） linearly increases with age, which may be a conse- quence of the scattering processes, and its value for a dynamical cold disk was found to be 8.0 ± 1.2 km s^-1. S_2 also linearly increases with metallicity, which indicates that radial migration is correlated to the metallicity gradient. On the other hand, the rotational velocity of the Sun around the Galactic center has no clear correlation with ages or metallicities of stars used in the estimation.

Galactic kinematics and structure defined by open clusters

On the basis of recently published astrophysical parameters of the open clusters, we have selected 301 clusters with measurements of their kinematical parameters to trace the local structure and kinematics of the Galactic disk. The present sample covers a range of over 3.0 kpc from the Sun and gives significant estimates of the disk structure and kinematical parameters of the Galaxy. We derive the disk scale height, vertical displacement of the Sun to the Galactic plane, solar motion with respect to the local standard of rest, circular speed of the Galactic rotation, Galactocentric distance from the Sun, etc. We found that the average scale height of the disk defined by the open clusters is Zh = 58 ± 4pc, with a vertical displacement of the Sun below the Galactic plane of z0 -= - 16±4 pc. Clusters with ages older than 50 Myr are less concentrated in the average plane （Zh=67 ±6pc） than the younger clusters （Zh = 51±5pc）. Using the approximation of axisymmetric circular rotation, we have derived the distance to the Galactic center from the Sun R0 = 8.03 ±0.70 kpc, which is in excellent agreement with the best estimate of the Galactocentric distance. From a kinematical analysis, we found an agedependent rotation of the Galaxy. The older clusters exhibit a lower velocity of vorticity, but have the same shear as the younger clusters. The mean rotation velocity of the Galaxy was obtained as 235 ± 10 km s-1.

Physical and Kinematical Characteristics of Wolf–Rayet Central Stars and their Host Planetary Nebulae

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.

The Yukawa and Exponential Potentials for a Galaxy’s Spherical Central Bulge*

By adding an extra term to the Newtonian potential, matter outside the orbit of a star adds to the gravitational acceleration acting on that star. In this work, we solve the Poisson equation for non-Newtonian potentials of a spherically symmetric distribution of mass. We derive equations for calculating the centripetal acceleration and velocity of galactic disk stars that are due to the Newtonian and exponential potentials of the galaxy’s central bulge.

Time Dilation Cosmology 2

This paper is a further elaboration of the author’s Time Dilation Cosmology (TDC) holographic model that ties gravitation and celestial mechanics and kinematics directly to time dilation, resolving all the major conundrums in astrophysics, and ties astrophysics directly to quantum physics. It begins with a brief summary of the TDC model and contains the new derivation for the time dilation version of the formula for summing relativistic velocities, Einstein’s gravitational constant and the time dilation versions for the Lorentz factor and the Euclidean norm of the 3d velocity vector, the two of which can then be used in the Four-velocity formula. It is demonstrated how orbital curvature is manifested as the resultant of two time dilation-manifested velocities. It also explains why an interferometer cannot distinguish free fall from zero gravity and further elaborates on the author’s previous explanations of how spiral galaxies are formed, and contains mathematical proof that Black Holes are actually Magnetospheric Eternally Collapsing Objects (MECOs) that are massless spacetime vortices.

LAMOST Experiment for Galactic Understanding and Exploration (LEGUE)——The survey's science plan

We describe the current plans for a spectroscopic survey of millions of stars in the Milky Way galaxy using the Guo Shou Jing Telescope （GSJT, formerly calledthe Large sky Area Multi-Object fiber Spectroscopic Telescope -- LAMOST）. The survey will obtain spectra for 2.5 million stars brighter than r 〈 19 during dark/grey time, and 5 million stars brighter than r 〈 17 or J 〈 16 on nights that are moonlit or have low transparency. The survey will begin in the fall of 2012, and will run for at least four years. The telescope＇s design constrains the optimal declination range for observations to 10~ 〈 di 〈 50~, and site conditions lead to an emphasis on stars in the direction of the Galactic anticenter. The survey is divided into three parts with different target selection strategies： disk, anticenter, and spheroid. The resulting dataset will be used to study the merger history of the Milky Way, the substructure and evolution of the disks, the nature of the first generation of stars through identification of the lowest metallicity stars, and star formation through study of open clusters and OB associations. Detailed design of the LAMOST Experiment for Galactic Understanding and Exploration （LEGUE） survey will be completed in summer 2012, after a review of the results of the pilot survey.

Halo stream candidates in the LAMOST DR2

We have cross-matched the LAMOST DR2 with the WISE, 2MASS and PPMXL catalogs and obtained a sample of 64 819 FGK metal-poor dwarfs with [Fe/H]〈-0.7, distances within 2 kpc from the Sun and reliable kinematics（space velocities,angular momenta and eccentricities）. With a detection strategy for halo streams provided by Klement et al, nine significant ＂phase-space overdensities＂ with stars on very similar orbits are identified from this sample. Among these overdensities, three were previously known and six are new stream candidates. The kinematics and metallicities of these stream candidates are then analyzed; they have typical halo characteristics.We have extracted the most probable members of each halo stream according to their angles with respect to the North Galactic Pole and investigate the distribution of the angular momenta to further verify their existences. Detailed study of elemental abundances for these members based on high resolution and high signal-to-noise spectra from follow-up observations in the near future is of high interest to understand the origin of these streams.

19 low mass hypervelocity star candidates from the first data release of the LAMOST survey

Hypervelocity stars are believed to be ejected out from the Galactic center through dynamical interactions between（binary） stars and the central supermassive black hole（s）. In this paper, we report 19 low mass F/G/K type hypervelocity star candidates from over one million stars found in the first data release of the LAMOST regular survey. We determine the unbound probability for each candidate using a MonteCarlo simulation by assuming a non-Gaussian proper-motion error distribution, and Gaussian heliocentric distance and radial velocity error distributions. The simulation results show that all the candidates have unbound possibilities over 50% as expected,and one of them may even exceed escape velocity with over 90% probability. In addition, we compare the metallicities of our candidates with the metallicity distribution functions of the Galactic bulge, disk, halo and globular clusters, and conclude that the Galactic bulge or disk is likely the birth place for our candidates.

The nature of orbits in a prolate elliptical galaxy model with a bulge and a dense nucleus

We study the transition from regular to chaotic motion in a prolate elliptical galaxy dynamical model with a bulge and a dense nucleus. Our numerical investigation shows that stars with angular momentum Lz less than or equal to a critical value Lzc, moving near the galactic plane, are scattered to higher z, when reaching the central region of the galaxy, thus displaying chaotic motion. An inverse square law relationship was found to exist between the radius of the bulge and the critical value Lzc of the angular momentum. On the other hand, a linear relationship exists between the mass of the nucleus and Lzc. The numerically obtained results are explained using theoretical arguments. Our study shows that there are connections between regular or chaotic motion and the physical parameters of the system, such as the star＇s angular momentum and mass, the scale length of the nucleus and the radius of the bulge. The results are compared with the outcomes of previous work.