A5042641984- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Galaxies: Formation, Evolution, Phenomena
- Calibration and Measurement Techniques
- Astrophysical Phenomena and Observations
- Spectroscopy and Laser Applications
- Scientific Research and Discoveries
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Astronomical and nuclear sciences
- CCD and CMOS Imaging Sensors
- Atmospheric Ozone and Climate
- Pulsars and Gravitational Waves Research
- High-pressure geophysics and materials
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Spacecraft and Cryogenic Technologies
- Advanced Fiber Laser Technologies
- SAS software applications and methods
UNSW Sydney
2015-2024
Astrobiology Center
2019
National Astronomical Observatories
2017
Chinese Academy of Sciences
2017
Center for Astrophysics Harvard & Smithsonian
2017
Optica
2017
Carnegie Institution for Science
2017
Carnegie Observatories
2017
University of Southern Queensland
2017
Pontificia Universidad Católica de Chile
2017
We present a catalog of nearby exoplanets, available at http://exoplanets.org and ApJ 646, 505 (published version the link above). It contains 172 known low mass companions with orbits established through radial velocity transit measurements around stars within 200 pc. include 5 previously unpublished exoplanets orbiting HD 11964, 66428, 99109, 107148, 164922. update for 90 additional including many whose have not been revised since their announcement, time series from Lick, Keck,...
We review the observed properties of exoplanets found by Doppler technique that has revealed 152 planets to date. focus on ongoing 18-year survey 1330 FGKM type stars at Lick, Keck, and Anglo-Australian Telescopes offers both uniform precision (3 m s-1) long duration. The 104 detected in this have minimum masses (M sin i) as low 6 MEarth, orbiting between 0.02 AU. core-accretion model planet formation is supported four observations: 1) mass distribution rises toward lowest detectable masses,...
We present the discovery of another seven Y dwarfs from Wide-field Infrared Survey Explorer (WISE). Using these objects, as well first six WISE dwarf discoveries Cushing et al., we further explore transition between spectral types T and Y. find that T/Y boundary roughly coincides with spot where J-H colors brown dwarfs, predicted by models, turn back to red. Moreover, use preliminary trigonometric parallax measurements show may also correspond point at which absolute H (1.6 um) W2 (4.6...
The Galactic Archaeology with HERMES (GALAH) Survey is a massive observational project to trace the Milky Way's history of star formation, chemical enrichment, stellar migration and minor mergers. Using high-resolution (R$\simeq$28,000) spectra taken High Efficiency Resolution Multi-Element Spectrograph (HERMES) instrument at Anglo-Australian Telescope (AAT), GALAH will determine parameters abundances up 29 elements for one million stars. Selecting targets from colour-unbiased catalogue...
We present the discovery of seven new T dwarfs identified in Two Micron All Sky Survey. Low-resolution (R$\sim$150) 0.8--2.5 micron spectroscopy obtained with IRTF SpeX instrument reveal characteristic H$_2$O and CH$_4$ bands spectra these brown dwarfs. Comparison to spectral standards observed same enable us derive classifications T3 T7 for objects this sample. Moderate-resolution (R$\sim$1200) near-infrared a subset discoveries K I line strengths consistent previously trends type....
We report final results from our 2.5 yr infrared parallax program carried out with the European Southern Observatory 3.5 m New Technology Telescope and SOFI camera. Our targeted precision astrometric observations of 10 T-type brown dwarfs in J band. Full solutions (including trigonometric parallaxes) for nine T are provided along proper-motion a further object. find that HgCdTe-based cameras capable delivering differential astrometry. For dwarfs, to be greatly preferred over optical, both...
We have made velocity observations of the star α Centauri B from two sites, allowing us to identify 37 oscillation modes with l = 0-3. Fitting these gives large and small frequency separations as a function frequency. The mode lifetime, measured scatter frequencies about smooth trend, is similar that in Sun. Limited δ Pav show oscillations centered at 2.3 mHz, peak amplitudes close solar. introduce new method measuring heavily smoothed power density spectra, which we estimated for Cen B, β...
While following up L dwarf candidates selected photometrically from the Two Micron All Sky Survey, we uncovered an unusual object designated 2MASS J01415823-4633574. Its optical spectrum exhibits very strong bands of vanadium oxide but abnormally weak absorptions by titanium oxide, potassium, and sodium. Morphologically such spectroscopic characteristics fall intermediate between old, field early-L dwarfs (log(g)~5) late M giants (log(g)~0), leading us to favor low gravity as explanation for...
We re-analyze 4 years of HARPS spectra the nearby M1.5 dwarf GJ 667C available through European Southern Observatory public archive. The new radial velocity (RV) measurements were obtained using a data analysis technique that derives Doppler measurement and other instrumental effects least-squares approach. Combining these 143 with 41 additional RVs from Magellan/Planet Finder Spectrograph Keck/High Resolution Echelle Spectrometer spectrometers reveals three signals beyond previously...
Using a large sample of optical spectra late-type dwarfs, we identify subset late-M through L field dwarfs that, because the presence low-gravity features in their spectra, are believed to be unusually young. From combined 303 find observationally that 7.6% ± 1.6% younger than 100 Myr. This percentage is agreement with theoretical predictions once observing biases taken into account. We these young tend fall southern hemisphere (decl . < 0°) and may previously unrecognized, low-mass members...
ABSTRACT We present a kinematic analysis of 152 low surface gravity M7-L8 dwarfs by adding 18 new parallaxes (including 10 for comparative field objects), 38 radial velocities, and 19 proper motions. also add low- or moderate-resolution near-infrared spectra 43 sources confirming their features. Among the full sample, we find 39 objects to be high-likelihood bona fide members nearby moving groups, 92 ambiguous 21 that are non-members. Using this age-calibrated investigate trends in...
We report the discovery of 76 new T dwarfs from UKIDSS Large Area Survey (LAS). Near-infrared broad and narrow-band photometry spectroscopy are presented for objects, along with WISE warm-Spitzer photometry. Proper motions 128 a two epoch LAS proper motion catalogue. use these to identify benchmark systems: LHS 6176AB, T8+M4 pair HD118865AB, T5.5+F8 pair. Using age constraints primaries evolutionary models constrain radii we have estimated their physical properties bolometric luminosity....
ABSTRACT We present updated simulations of the detectability Jupiter analogs by 17-year Anglo-Australian Planet Search. The occurrence rate Jupiter-like planets that have remained near their formation locations beyond ice line is a critical datum necessary to constrain details planet formation. It also vital in our quest fully understand how common (or rare) planetary systems like own are Galaxy. From sample 202 solar-type stars, and correcting for imperfect on star-by-star basis, we derive...
Context. The abilities of radial velocity exoplanet surveys to detect the lowest-mass extra-solar planets are currently limited by a combination instrument precision, lack data, and "jitter". Jitter is general term for any unknown features in noise, reflects detailed knowledge stellar physics (asteroseismology, starspots, magnetic cycles, granulation, other surface phenomena), as well possible underestimation noise.
ABSTRACT Our understanding of planetary systems different to our own has grown dramatically in the past 30 yr. However, efforts ascertain degree which Solar system is abnormal or unique have been hindered by observational biases inherent methods that yielded greatest exoplanet hauls. On basis such surveys, one might consider highly unusual – but reality we are only now beginning uncover true picture. In this work, use full 18-yr archive data from Anglo-Australian Planet Search examine...
Determining the orbital eccentricity of an extrasolar planet is critically important for understanding system's dynamical environment and history. However, often poorly determined or entirely mischaracterized due to poor observational sampling, low signal-to-noise, and/or degeneracies with other planetary signals. Some systems previously thought contain a single, moderate-eccentricity have been shown, after further monitoring, host two planets on nearly-circular orbits. We investigate...
We explore the fundamental relations governing radial and vertical velocity dispersions of stars in Milky Way, from combined studies complementary surveys including GALAH, LAMOST, APOGEE, NASA $Kepler$ K2 missions, $Gaia$ DR2. find that different stellar samples, even though they target tracer populations employ a variety age estimation techniques, follow same set relations. provide clearest evidence to date that, addition well-known dependence on age, depend orbital angular momentum $L_z$,...
Abstract We analyze 5108 AFGKM stars with at least five high-precision radial velocity points, as well Gaia and Hipparcos astrometric data, utilizing a novel pipeline developed in previous work. find 914 signals periods longer than 1000 days. Around these signals, 167 cold giants 68 other types of companions are identified, through combined analyses velocity, astrometry, imaging data. Without correcting for detection bias, we estimate the minimum occurrence rate wide-orbit brown dwarfs to be...
Precise Doppler measurements from the Anglo-Australian Telescope (AAT) UCLES spectrometer reveal periodic Keplerian velocity variations in stars HD 160691 and 27442. has a period of 743 days, semiamplitude 54 m s-1, high eccentricity, e = 0.62, typical extrasolar planets orbiting beyond 0.2 AU. The minimum (M sin i) mass companion is 1.97 MJ, semimajor axis 1.65 27442 415 day period, 32 an eccentricity 0.058. 1.43 1.18 This first planet AU that circular orbit similar to solar system planets....
New radial velocities of α Cen A & B obtained in the framework Anglo-Australian Planet Search programme as well CORALIE are added to those by Endl et al. ([CITE]) improve precision orbital parameters. The resulting masses and for respectively. factors limiting how accurately these can be derived from a combined visual-spectroscopic solution investigated. total effect convective blueshift gravitational redshift is also investigated estimated differ m s-1 between components. This suggests that...
The amplitudes of solar-like oscillations depend on the excitation and damping, both which are controlled by convection. Comparing observations with theory should therefore improve our understanding underlying physics. However, theoretical models invariably compute oscillation relative to Sun, it is vital have a good calibration solar amplitude using stellar techniques. We used daytime spectra obtained HARPS UCLES, measure made detailed comparison BiSON helioseismology instrument. find that...
We have acquired high-resolution echelle spectra of 225 F6-M5 type stars in the southern hemisphere. The are targets or candidates to be for Anglo-Australian Planet Search. CaII HK line cores were used derive activity indices all these objects. converted Mt. Wilson system measurements and logR'HK values determined. A number had no previously derived indices. In addition we also included from Tinney et al. (2002) using our calibration. radial-velocity instability (also known as jitter) level...