A5057030638- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Atmospheric Ozone and Climate
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Molecular Spectroscopy and Structure
- GNSS positioning and interference
- Astrophysical Phenomena and Observations
- Spectroscopy and Laser Applications
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Historical Geography and Cartography
- History and Developments in Astronomy
- Hybrid Renewable Energy Systems
- Radioactive contamination and transfer
- Nuclear reactor physics and engineering
- Geology and Paleoclimatology Research
- Radioactive element chemistry and processing
- Inorganic Fluorides and Related Compounds
- Laser Design and Applications
- Advanced Chemical Physics Studies
National Time Service Center
2017-2025
Chinese Academy of Sciences
2016-2025
University of Chinese Academy of Sciences
2014-2025
Shanghai Astronomical Observatory
2014-2024
International Centre for Radio Astronomy Research
2016
Curtin University
2016
The central molecular zone (CMZ) of our Galaxy exhibits widespread emission from SiO and various complex organic molecules (COMs), yet the exact origin such is uncertain. Here we report discovery a unique class long (>0.5 pc) narrow (<0.03 filaments in 5–4 eight additional lines, including several COMs, ALMA 1.3 mm spectral line observations toward two massive clouds CMZ, which name as slim filaments. However, these are not detected continuum at 5 σ level. Their line-of-sight...
Given that effective angular momentum (EAM) data demonstrate a strong correlation with length of day (LOD) and are extensively utilized in the prediction universal time (UT1), this research integrated EAM into design Kalman filter. At solution combination level, UT1, LOD, were merged to derive UT1/LOD sequence featuring higher accuracy enhanced continuity. To begin with, comprehensive evaluation three datasets was conducted identify systematic biases periodic components LOD. Subsequently,...
We report the results of our systematic survey for Galactic 6.7 GHz Class II CH$_3$OH maser emission toward a sample young stellar objects. The was conducted with Shanghai Tianma Radio Telescope (TMRT). consists 3348 sources selected from all-sky \emph{Wide-Field Infrared Survey Explorer (WISE)} point source catalog. have discussed selection criteria in detail and detection those at high latitudes (i.e. $|b|>$ 2$^\circ$) previous paper (paper I). Here, we present low latitudes, i.e....
We have used the Australia Telescope Compact Array to search for emission from 4−1 → 30E transition of methanol (36.2 GHz) toward center nearby starburst galaxy NGC 253. Two regions were detected, offset nucleus along same position angle as inner spiral arms. The is largely unresolved on a scale 5'', has FWHM line width <30 km s−1, and an isotropic luminosity orders magnitude larger than that observed in any Galactic star formation region. These characteristics suggest 36.2 GHz most likely...
We have detected emission from both the E (36.2 GHz) class I and (37.7 II methanol transitions toward center of closest ultra-luminous infrared galaxy Arp 220. The in shows narrow spectral features has luminosities approximately 8 orders magnitude stronger than those observed typical masers Galactic star formation regions. is also expected intensity thermal these based on findings we suggest that two are masers. These observations provide first detection a megamaser 36.2 37.7 GHz represent...
We have used the Australia Telescope Compact Array (ATCA) to observe 36.2-GHz class I methanol maser emission towards NGC253 and find that it is located at interface between nuclear ring both ends of galactic bar. This thought be location inner Linblad resonance we suggest in this region likely due large-scale cloud-cloud collisions. detected first extragalactic 44.1-GHz associated with emission. In contrast masers found Galactic star formation regions, two orders magnitude weaker than...
Abstract We performed a systematic 6.7 GHz Class II methanol maser survey using the Shanghai Tianma Radio Telescope toward targets selected from all-sky Wide-Field Infrared Survey Explorer ( WISE ) point catalog. In this paper, we report results of those at high Galactic latitudes, i.e., <?CDATA $| b| \,\gt $?> 2°. Of 1473 sources latitude, 17 positions that were actually associated with 12 detected emission, reflecting rarity (1%–2%) masers in region away plane. Out sources, 3 are for first...
ABSTRACT We report on OH maser emission toward G336.644−0.695 (IRAS 16333−4807), which is a H 2 O maser-emitting Planetary Nebula (PN). have detected 1612, 1667, and 1720 MHz masers at two epochs using the Australia Telescope Compact Array, hereby confirming it as seventh known case of an OH-maser-emitting PN. This only second PN showing after K 3−35 evolved stellar object with strongest transition. one group very young PNe. The 1612 1667 are similar velocity to 22 GHz masers, whereas show...
Data for a number of OH maser lines have been collected from surveys. The positions are compared with recent mid-infrared (MIR) surveys such as the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) and Wide-field Explorer (WISE) surveys, restricting comparison to point sources. colours intensities IR sources compared. There many 18-cm masers, but far fewer in arising higher energy levels. We also make 5-cm Class II methanol masers. divided results into three...
Abstract We report the detection of maser emission from transition at 36.4 GHz toward nearby starburst galaxy NGC 253. This is first this in either a Galactic or extragalactic source. The has brightness temperature excess 2500 K and offset center by approximately 18″ (300 pc), but close to previously reported class I methanol maser. Both masers appear arise near interface between galactic bar central molecular zone, where it thought that gas being transported inwards, producing region...
We present high spatial resolution observations of ground-state OH masers achieved with the Australia Telescope Compact Array (ATCA). These targeted 253 pointing centres containing maser candidates at all four transitions identified in Southern Parkes Large-Area Survey Hydroxyl (SPLASH) across 96 square degrees Galactic plane (332\degree$<l<$334\degree and $-$2\degree$<b<+$2\degree, 344\degree$<l<$355\degree 358\degree$<l<$4\degree $+$2\degree$<b<+$6\degree, 5\degree$<l<$10\degree...
We have searched for emission from the 36.2 GHz () methanol transition toward NGC 4945, using Australia Telescope Compact Array. was detected offset southeast Galactic nucleus. The is narrow, with a line width <10 km s−1 and luminosity five orders of magnitude higher than class I masers same transition. These characteristics combined physical separation strong central thermal suggests that maser. This factor ∼90 more luminous widespread Milky Way molecular zone. fourth detection...
ABSTRACT We report on high spatial resolution observations, using the Australia Telescope Compact Array (ATCA), of ground-state OH masers. These observations were carried out toward 196 pointing centers previously identified in Southern Parkes Large-Area Survey Hydroxyl (SPLASH) pilot region, between Galactic longitudes 334° and 344° latitudes −2° +2°. Supplementing our data with from MAGMO (Mapping Magnetic field through masers) survey, we find maser emission 175 target fields. conclude...
ABSTRACT We have performed high-sensitivity mapping observations of several complex organic molecules around Sagittarius B2 with the ARO 12 m telescope at 3 mm wavelength. Based on their spatial distribution, can be classified as either ‘extended’, those detected not only in Sgr B2(N) and B2(M), or ‘compact’, toward near B2(M). The ‘extended’ include glycolaldehyde (CH2OHCHO), methyl formate (CH3OCHO), formic acid (t-HCOOH), ethanol (C2H5OH) amine (CH3NH2), while ‘compact’ dimethyl ether...
Abstract We report pulsar timing observations carried out in L -band with NTSC’s 40-meter Haoping Radio Telescope (HRT), which was constructed 2014. These were using the machine we developed. Timing toward millisecond J0437–4715 obtain a residual (r.m.s.) of 397 ns time span 284 days. Our successfully detected Crab pulsar’s glitch that happened on 2019 July 23.
Abstract We present high spatial resolution observations of ground-state OH masers achieved using the Australia Telescope Compact Array (ATCA). These were conducted toward 171 pointing centers where maser candidates identified previously in Southern Parkes Large-Area Survey Hydroxyl Galactic center region between longitudes 355 ◦ and 5 latitudes −2° +2°. detect emission 162 target fields suggest that six out nine nondetections are due to intrinsic variability. Due superior follow-up ATCA...
ABSTRACT The evolution of asymptotic giant branch stars from the spherical symmetry into diverse shapes planetary nebulae (PNe) is a topic intensive research. Young PNe provide unique opportunity to characterize onset this transitional phase. In particular, OH maser-emitting (OHPNe) are considered nascent PNe. fact, only six OHPNe have been confirmed date. order identify and more OHPNe, we processed unpublished continuum data interferometric follow-up Southern Parkes Large-Area Survey in...
Abstract We have used the Shanghai Tianma Radio Telescope to search for three OH transitions at 4.7 GHz toward 155 northern star formation regions. detect masers in 18 regions, 8 of which are reported here first time. From these sources, we 6 4660 MHz masers, 13 4765 and no 4750 masers. A further 1 source (Sgr B2N) has been re-detected with broad quasi-thermal emission all lines. W49SW was both MHz. One (W31, G010.626−0.387) (G005.885−0.392) detected investigated associations between...
Abstract Ground-state OH masers identified in the Southern Parkes Large-Area Survey Hydroxyl were observed with Australia Telescope Compact Array to obtain positions high accuracy (~1 arcsec). We classified these into evolved star maser sites, formation supernova remnant planetary nebula sites and unknown using their accurate positions. Evolved Galactic Centre region (between longitudes of −5° +5° latitudes −2° +2°) studied detail understand distributions.
Water fountain objects are generally defined as "evolved stars with low to intermediate initial mass accompanied by high-velocity molecular jets detectable in the 22.235 GHz H$_2$O maser line". They key of understanding morphological transitions circumstellar envelopes during post asymptotic giant branch phase. Masers useful tools trace kinematic environments envelopes. In this letter we report discovery exceptionally uncommon excited-state hydroxyl (ex-OH) masers at 4660 and 6031 MHz toward...
Abstract Water fountain objects are generally defined as evolved stars with low to intermediate initial mass accompanied by high-velocity molecular jets detectable in the 22.235 GHz H 2 O maser line. They key of understanding morphological transitions circumstellar envelopes during post asymptotic giant branch phase. Masers useful tools trace kinematic environments envelopes. In this Letter we report discovery exceptionally uncommon excited-state hydroxyl (ex-OH) masers at 4660 and 6031 MHz...
Abstract We present the first detection of ground-state OH emission line at 1612 MHz toward prototypical carbon-rich planetary nebula (PN) NGC 7027, utilizing newly installed ultrawideband (UWB) receiver Five-hundred-meter Aperture Spherical radio Telescope (FAST). This is likely to originate from interface neutral shell and ionized region. The other three lines 1665, 1667, 1721 are observed in absorption have velocities well matched with that HCO + absorption. infer outer although...
The Length of Day (LOD) and the Universal Time (UT1) play crucial roles in satellite positioning, deep space exploration, related fields. primary method for predicting LOD UT1 is least squares fitting combined with autoregressive (AR) models. Polynomial Curve Fitting (PCF) has greater accuracy capturing long-term trends compared to standard fitting. In this study, PCF Weighted Least Squares (WLS) employed fit extrapolate periodic trend components series after removing tidal influences....
Abstract We present a 6.0 GHz excited-state OH maser survey toward 155 northern star formation regions utilizing the Shanghai Tianma Radio Telescope. In total, we detect 44 masers, 8 of which are new detections (one at 6016 MHz, two 6030 and five 6035 MHz). Of these detected 13 sites exhibit MHz all show transition, one site (G009.620+0.194) has only maser, (W3(OH)) shows 6049 maser. The is first this transition in regions. Investigations association between 6030/6035 masers with 1665...
We present the first detection of ground-state OH emission line at 1612 MHz toward prototypical carbon-rich planetary nebula (PN) NGC 7027, utilizing newly installed ultra-wideband (UWB) receiver Five-hundred-meter Aperture Spherical radio Telescope (FAST). This is likely to originate from interface neutral shell and ionized region. The other three lines 1665, 1667, 1721 are observed in absorption have velocities well matched with that HCO$^+$ absorption. infer outer although possibility...