Search Publications
Understanding the Velocity Distribution of the Galactic Bulge with APOGEE and Gaia
Mao, Shude; Liu, Chao; Fernández-Trincado, José G. +5 more
We revisit the stellar velocity distribution in the Galactic bulge/bar region with Apache Point Observatory Galactic Evolution Experiment DR16 and Gaia DR2, focusing in particular on the possible high-velocity (HV) peaks and their physical origin. We fit the velocity distributions with two different models, namely with Gauss-Hermite polynomials an…
A young spectroscopic binary in a quintuple system part of the Local Association
Murgas, Felipe; Jeffers, Sandra V.; McCully, Curtis +9 more
Context. Double-lined spectroscopic (SB2) binaries allow us to obtain a direct determination of the masses of their components, which is essential to test stellar models. Although these objects only provide a lower limit for the mass, they are more abundant than their eclipsing counterparts as they are not as strongly limited by the inclination of…
A Stringent Test of Magnetic Models of Stellar Evolution
Torres, Guillermo; Vanderburg, Andrew; Curtis, Jason L. +1 more
Main-sequence stars with convective envelopes often appear larger and cooler than predicted by standard models of stellar evolution for their measured masses. This is believed to be caused by stellar activity. In a recent study, accurate measurements were published for the K-type components of the 1.62-day detached eclipsing binary EPIC 219511354,…
The nearby spiral density-wave structure of the Galaxy: line-of-sight velocities of the Gaia DR2 OB stars
Gedalin, Michael; Jiang, Ing-Guey; Griv, Evgeny
Distances and line-of-sight velocities of 964 Gaia Data Release 2 (DR2) OB stars of Xu et al. within 3 kpc from the Sun and 500 pc from the Galactic mid-plane with accuracies of <50 per cent are selected. The data are used to find small systematic departures of velocities from the mean circular motion for the stars in the solar neighborhood due…
The time delay of CLASS B1600+434 from VLA multi-frequency and polarization monitoring
Biggs, A. D.
We present an analysis of archival multi-frequency Very Large Array monitoring data of the two-image gravitational lens system CLASS B1600+434, including the polarization properties at 8.5 GHz. From simulating radio light curves incorporating realistic external variability in image A, we find time delays consistent at 1σ for all frequencies and in…
A Grid of Synthetic Spectra for Subdwarfs: Non-LTE Line-blanketed Atmosphere Models
Diaz, Marcos P.; Levenhagen, Ronaldo S.; Coelho, Paula R. T. +1 more
A new grid of detailed atmosphere model spectra for hot and moderately cool subdwarf stars is presented. High-resolution spectra and synthetic photometry are calculated in the range from 1000-10,000 Å using non-LTE fully line-blanketed atmosphere structures. Our grid covers eight temperatures within 10,000 ≤ Teff [K] ≤ 65,000, three sur…
HH 175: a giant Herbig-Haro flow emanating from a multiple protostar
Friberg, Per; Reipurth, Bo
HH 175 is an isolated Herbig-Haro object seen towards the B35 cloud in the λ Ori region. We use deep Subaru 8 m interference filter images and Spitzer images to show that HH 175 is a terminal shock in a large collimated outflow from the nearby embedded source IRAS 05417+0907. The body of the eastern outflow lobe is hidden by a dense ridge of gas. …
Predicting the CME arrival time based on the recommendation algorithm
Luo, Bingxian; Liu, Zhu; Li, Ming +9 more
CME is one of the important events in the sun-earth system as it can induce geomagnetic disturbance and an associated space environment effect. It is of special significance to predict whether CME will reach the Earth and when it will arrive. In this paper, we firstly built a new multiple association list for 215 different events with 18 character…
The former companion of hyper-velocity star S5-HVS1
Hosek, Matthew W., Jr.; Li, Ting S.; Do, Tuan +4 more
The hyper-velocity star S5-HVS1, ejected 5 Myr ago from the Galactic Centre at 1800 km s-1, was most likely produced by tidal break-up of a tight binary by the supermassive black hole SgrA*. Taking a Monte Carlo approach, we show that the former companion of S5-HVS1 was likely a main-sequence star between 1.2 and 6 M⊙ and was…
LBV phenomenon and binarity: The environment of HR Car
Mehner, A.; de Wit, W. -J.; Agliozzo, C. +7 more
Luminous blue variable stars (LBVs) are of great interest in massive-star evolution as they experience very high mass-loss episodes within short periods of time. HR Car is a famous member of this class in the Galaxy. It has a large circumstellar nebula and has also been confirmed as being in a binary system. One means of gaining information about …