A5073427860- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Molecular Spectroscopy and Structure
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Atmospheric Ozone and Climate
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Calibration and Measurement Techniques
- Planetary Science and Exploration
- History and Developments in Astronomy
- Pulsars and Gravitational Waves Research
- Methane Hydrates and Related Phenomena
- Solar and Space Plasma Dynamics
- Mental Health and Patient Involvement
- GNSS positioning and interference
- Atomic and Molecular Physics
- Analytical Chemistry and Sensors
- Ionosphere and magnetosphere dynamics
Sun Yat-sen University
2020-2024
Ural Federal University
2014-2019
University of Hong Kong
2008-2016
Chinese University of Hong Kong
2012
University of Illinois Urbana-Champaign
2003-2011
Institute of Astronomy and Astrophysics, Academia Sinica
2005-2009
Astronomical Observatory
2001-2007
Shinshu University
2006
Academia Sinica
2006
The Graduate University for Advanced Studies, SOKENDAI
2001-2005
A survey of the Milky Way disk and Magellanic System at wavelengths 21-cm atomic hydrogen (HI) line three 18-cm lines OH molecule will be carried out with Australian Square Kilometre Array Pathfinder telescope. The study distribution HI emission absorption unprecedented angular velocity resolution, as well molecular thermal emission, absorption, maser lines. area to covered includes Galactic plane (|b|< 10deg) all declinations south delta = +40deg, spanning longitudes 167deg through 360deg...
Abstract IRAS source 19312+1950 (hereafter I19312) is an infrared point with maser emissions of SiO, H 2 O, and OH molecules. Although initial observations suggested that I19312 might be evolved star, its characteristics are not fully consistent this classification. This study aims to further investigate the nature by conducting long-term monitoring comparing results other known astrophysical objects. We conducted using single-dish radio telescopes. The were then compared historical data...
A long-standing enigma in observational astronomy is the identification of so-called 21,μm feature a subset envelopes post-asymptotic giant branch (post-AGB) stars. Identifying this transient important for understanding chemical processes during brief post-AGB phase and enrichment interstellar medium. Understanding structures environments these objects prerequisite endeavor. We investigate structure circumstellar envelope spatial distribution gas-phase molecules source IRAS 23304+6147 with...
We report the results of multi-epoch VLBA observations 22.2GHz water maser emission associated with "water fountain" IRAS 18286-0959. suggest that this object is second example a highly collimated bipolar precessing outflow traced by emission, other W43A. The detected peaks are distributed over velocity range from -50km/s to 150km/s. spatial distribution 70% identified features found be along spiral jet (jet 1) extended southeast northwest, remaining appear trace another 2) different...
Abstract Water fountains (WFs) are thought to be objects in the morphological evolution of circumstellar envelopes low- and intermediate-mass evolved stars, transitioning from spherically symmetric asymmetric shapes. We used databases 1612 MHz OH 22.235 GHz H 2 O maser sources search for new WF candidates using criterion a larger velocity range emission compared that emission. Thus, it is principle possible identify WFs with ranges smaller than those previously known WFs. For line, we...
Abstract We present the results of observations cold IRAS sources in Galactic disk area, $-10^{\circ} &lt; l 100^{\circ}$ and $\vert b\vert 5^{\circ}$, SiO $J = 1\hbox{--}0$, $v 1$ 2 maser lines. masers were detected 51 out 143 observed sources; 45 new detections masers. The selected objects with dust temperatures between 160 280 K. According to a confirmation using 2MASS near-infrared images, majority sample are AGB or post-AGB stars, although dense cores star-forming regions (or dusty...
We report Very Long Baseline Array and Large observations of 22 GHz H2O 43 SiO (v = 1, J 1-0) maser emission as well 7 mm continuum in W43A, which exhibits a highly collimated jet molecular gas spherically expanding envelope very similar to that an OH/IR star. The spatiokinematical structure the masers is fitted precessing model with expansion velocity 150 km s-1 dynamical age ∼50 yr. biconically flow model, whose axis parallel direction jet. Astrometry suggests these sources have common...
Abstract We surveyed 401 color-selected IRAS sources in the galactic disk SiO $J = 1 \hbox{--} 0, v 1$ and 2 maser lines at 43 GHz, resulting 254 (239 new) detections. The observed lie mostly a strip of inner with boundaries $-10^{\circ} &lt; l 40^{\circ}$ $\vert b\vert 3^{\circ}$. This survey provides radial velocities inner-disk stars for which optical measurements cannot be made due to interstellar extinction. $l v$ diagram area exhibits fewer objects coincident molecular ring feature...
A survey has been made in the SiO J = 1-0, v 1 and 2 transitions (∼43 GHz) for color-selected IRAS sources central region of Galaxy, -10° < l 15° (except |l| ≤ 3°) |b| 3°, with Nobeyama 45 m telescope. We have detected 124 out 200 observed masers. Distances to range approximately from 11 kpc, if estimated 12 25 μm flux densities. Radial velocities spread between ±260 km s-1. The distribution longitude-velocity diagram is compared H I contours. number are limiting velocities; a group...
We have surveyed ~400 known large-amplitude variables within 15' of the galactic center in SiO J=1--0 v=1 and 2 maser lines at 43 GHz, resulting 179 detections. were also detected from 16 other 180 sources, which are located 20" (the telescope half beamwidth) program objects. The detection rate 48 percent is comparable to that obtained Bulge IRAS source surveys. Among detections, five stars radial velocities greater than 200 km/s. increases steeply with period light variation, particularly...
We present the results of SiO millimeter line observations a sample known maser sources covering wide dust temperature range. A cold part was selected from found in our recent survey dusty objects. The aim research is to investigate causes correlation between infrared colors and intensity ratios among different transition lines. In particular, ratio J = 1-0 v 1, 2, 3 lines are main concern this paper. observed total 75 with Nobeyama 45 m telescope quasi-simultaneously 0, 3, 4 2-1 2 also...
We present the results of a 22 GHz H2O maser survey toward new sample asymptotic giant branch (AGB) and post-AGB star candidates. Most objects are selected for first time based on AKARI data, which have high flux sensitivity in mid-infrared ranges. aim at finding sources transient phase between AGB stages evolution, where envelopes start to develop large deviations from spherical symmetry. The observations were carried out with Effelsberg 100 m radio telescope. Among 204 observed objects, 63...
Abstract We report first on two-epoch mapping observations of SiO $v =$ 3 $J 1–0 maser emission in the semiregular variable W Hydrae using Japanese VLBI Network. The flux density detected 2009 February 28 was two orders magnitude smaller than those 1 and 2 emissions, while a month half later suddenly increased by factor $\sim $25. In contrast, densities decreased during this period, as expected from optical light curve. At epoch, features were located inside ring composed 6 mas ($\gtrsim...
Abstract We report on the time variation of SiO maser emission from symbiotic stellar system V407 Cygni after classical nova outburst 2010 March 10. Although both $J$$=$ 1–0 $v$$=$ 1 and 2 lines at 43.122 42.821 GHz were found previously in envelope a mira binary system, only weak line has continuously been detectable outburst. The profile exhibited dramatic change several weeks burst; component higher-velocity side systemic velocity disappeared two burst, new persistent appeared...
Using the Very Long Baseline Array and European Interferometry Network, we have observed 22.2 GHz H2O 1612 MHz OH masers in water fountain source IRAS 18460−0151. The maser spectrum has a very wide line-of-sight velocity range (≈310 km s−1) consists of three groups emission features at blueshifted (−68 s−1≲ VLSR ≲ −17 redshifted (VLSR ≃ 240 edges as well around systemic (112 s−1 133 s−1). first two spectral components exhibit highly collimated high-velocity bipolar jet on sky, with an...
Abstract One of the major puzzles in study stellar evolution is formation process bipolar and multipolar planetary nebulae. There growing consensus that collimated jets create cavities with dense walls slowly expanding (10–20 km s −1 ) envelope ejected previous evolutionary phases, leading to observed morphologies. However, launching jet way it interacts circumstellar material such asymmetric morphologies have remained poorly known. Here we present for first time CO emission from asymptotic...
Abstract We searched for the SiO $J=1$-0, $v= 1$ and 2 maser lines at $\sim 43$ GHz in 277 MASS/MSX/IRAS sources off Galactic plane ($\vert b\vert\gtrsim 3^{\circ}$), which resulted 119 (112 new) detections. Among new detections, two are very faint objects with MSX 12$\mu$m flux densities below Jy. These likely to be O-rich AGB-stars associated dwarf-galaxy tidal tails. The sample also includes medium bright moderately high galactic latitudes ($3^{\circ}&lt;\vert...
Using the 3.6/4.5/5.8/8.0 micron images with 1.2 arcsec pixel resolution from Spitzer/GLIMPSE survey, we investigated 23 masing and 18 very red objects that were not identified in 2MASS survey. Counterparts for all selected found GLIMPSE images. Color indices these IR bands suggest presence of a high-extinction layer more than few tenths solar mass front central star. Furthermore, radio observations SiO H2O maser lines characteristic maser-line spectra embedded objects, e.g., J=1-0 line...
We observed four "water fountain" sources in the CO J=3-2 line emission with Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope 2010-2011. The water fountain are evolved stars that form high-velocity collimated jets traced by maser emission. was detected only from IRAS 16342-3814. present work confirmed ^{12}CO to ^{13}CO intensity ratio is ~1.5 at systemic velocity. discuss origins of very low ratio, as possible evidence for "hot-bottom burning" an oxygen-rich star, and variation
The IRAS source, 19312+1950, exhibits SiO maser emission, which is predominantly detected in evolved stars enshrouded by a cold molecular envelope. In fact, the mojority of observational properties 19312+1950 consistent with nature an asymptotic giant branch (AGB) star or post-AGB star. Interestingly, however, some cannot be readily explained within standard scheme stellar evolution, and those are rather reminiscent young objects. present research we considered evolutionary status as...
We explored an efficient method to identify evolved stars with oxygen-rich envelopes in the late asymptotic giant branch (AGB) or post-AGB phase of stellar evolution, which include a rare class objects—the "water fountains (WF)." Our considers OH and H2O maser spectra, near-infrared Q-parameters (these are color indices accounting for effect extinction), far-infrared AKARI colors. Here we first present results new survey on masers. There were 108 color-selected objects: 53 them observed...
We report on the detection of SiO and water masers toward a newly found bipolar nebula, IRAS 19312+1950. This object exhibits extreme red color log (F25/F12)=0.5 (F60/F25)=0.7 nebulosity having size about 30" extended to South-West in 2MASS near-infrared image. Toward this object, we have detected emission from H2O 6(1,6)-5(2,3) transition, J=1-0, v=1 2, J=2-1, transitions, SO 2(2)--1(1) H13CN J=1-0 transitions. The thermal lines are shifted by 12 km/s radial velocity with respect maser...
We have surveyed known large-amplitude variables within $ 15'$ of the Galactic center in SiO J=1 \hbox{--} 0$$ v=1$ and 2 maser lines at 43 GHz, resulting 79 detections 58 non-detections. The detection rate percent is comparable to that obtained Bulge IRAS source surveys. were also detected from four other sources near program objects. increases steeply with period, particularly for stars $P \gt 500 \,\mathrm{d}$$ P \,\mathrm{d}$, where it exceeds 80%. found a given period approximately...
We report on the results of a Submillimeter Array (SMA) interferometric observation proto-planetary nebula CRL 618 in 12CO J = 6-5 line. With new capability SMA enabling us to use two receivers at time, we also observed simultaneously 2-1 and 13CO lines. The lines were interferometrically for first time toward 618. flux high-velocity component line is almost fully recovered, while roughly 80% low-velocity resolved out. low recovery rate suggests that emission region largely extended....
We present the results of a molecular line survey extreme carbon star CRL 3068. The observations were carried out with Arizona Radio Observatory (ARO) 12 m telescope and Heinrich Hertz Submillimeter Telescope (SMT) at λ 2 mm 1.3 atmospheric windows. cover frequency bands from 130 to 162 GHz 219.5 267.5 GHz. typical sensitivities achieved are TR < 15 mK 7 for ARO SMT, respectively. Seventy-two individual emission features belonging 23 species isotopologues detected. Only three faint lines...