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A Catalog of LAMOST Variable Sources Based on Time-domain Photometry of ZTF
Mei, Ying; Wang, Feng; Deng, Hui +4 more
The identification and analysis of different variable sources is a hot topic in astrophysical research. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic survey has accumulated a mass of spectral data but contains no information about variable sources. Although a few related studies present variable source catalo…
Role of Topocentric Parallax in Near-Earth Object Initial Orbit Determination
Zhai, Chengxing; Shao, Michael; Saini, Navtej S. +5 more
Near-Earth Object (NEO) initial orbit determination typically uses astrometric measurements during a close approach over a time window much shorter than the orbital period of the NEO. The initial orbit is only weakly determined with dominant uncertainties in the distance of the NEO from the Earth. Topocentric astrometric measurements allow us to e…
Post-Newtonian gravity and Gaia-like astrometry. Effect of PPN γ uncertainty on parallaxes
Bucciarelli, Beatrice; Lattanzi, Mario G.; Crosta, Mariateresa +3 more
Context. Relativistic models of light propagation adopted for high-precision astrometry are based on the parametrised post-Newtonian formalism, which provides a framework for examining the effects of a hypothetical violation of general relativity on astrometric data. Astrometric observations are strongly affected by the post-Newtonian (PPN) parame…
Three-dimensional analyses of an aspherical coronal mass ejection and its driven shock
Feng, Li; Lu, Lei; Gan, Weiqun +4 more
Context. Observations reveal that shocks can be driven by fast coronal mass ejections (CMEs) and play essential roles in particle accelerations. A critical ratio, δ, derived from a shock standoff distance normalized by the radius of curvature (ROC) of a CME, allows us to estimate shock and ambient coronal parameters. However, true ROCs of CMEs are…
Decoding NGC 628 with radiative transfer methods
Popescu, C. C.; Pricopi, D.; Natale, G. +2 more
We present an axi-symmetric model for the ultraviolet (UV)-to-submillimetre (submm) images of the nearly face-on spiral galaxy NGC 628. It was calculated using a radiative transfer (RT) code, accounting for the absorption and re-emission of starlight by dust in the interstellar medium of this galaxy. The code incorporates emission from Polycyclic …
On the Same Wavelength as the Space Telescope Imaging Spectrograph
Ayres, Thomas R.
The Hubble Space Telescope Imaging Spectrograph (STIS) is a powerful tool for high spectral resolution ultraviolet (UV; 1150-3200 Å) studies of bright cosmic sources. However, achieving the superb wavelength precision inherent in its UV echelle channels is hampered by subtle camera distortions that are not fully compensated for by the CALSTIS pipe…
Down but Not Out: Properties of the Molecular Gas in the Stripped Virgo Cluster Early-type Galaxy NGC 4526
Meier, David S.; Davis, Timothy A.; Young, Lisa M. +2 more
We present Atacama Large Millimeter/submillimeter Array data on the 3 mm continuum emission, CO isotopologues (12CO, 13CO, and C18O), and high-density molecular tracers (HCN, HCO+, HNC, HNCO, CS, CN, and CH3OH) in NGC 4526. These data enable a detailed study of the physical properties of the m…
The Substructures in the Anticenter Region of the Milky Way
Zhao, G.; Chen, Y. Q.; Zhang, Z. +3 more
We investigated the observational properties of Triangulum-Andromeda (TriAnd), Monoceros Ring (MRi), and Anti-Center Stream (ACS) in the anticenter region using K giants, M giants, and RGB stars from LAMOST and SDSS survey. The Friends of Friends algorithm was applied to select member stars of these structures. We found a new spur of TriAnd at l ~…
Accretion and Extinction Variations in the Low-mass Pre-main-sequence Binary System WX Cha
Pál, András; Ábrahám, Péter; Kóspál, Ágnes +5 more
Light curves of young star systems show photometric variability due to different kinematic and physical processes. One of the main contributors to the photometric variability is the changing mass accretion rate, which regulates the interplay between the forming young star and the protoplanetary disk. We collected high-resolution spectroscopy in ei…
The rotation of planet-hosting stars
Feldmann, Robert; Helled, Ravit; Sibony, Yves
Understanding the distribution of angular momentum during the formation of planetary systems is a key topic in astrophysics. Data from the Kepler and Gaia missions allow to investigate whether stellar rotation is correlated with the presence of planets around Sun-like stars. Here, we perform a statistical analysis of the rotation period of 493 pla…