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The local vertical density distribution of ultracool dwarfs M7 to L2.5 and their luminosity function
Warren, Stephen J.; Ahmed, Saad; Laithwaite, Richard C.
We investigate the form of the local vertical density profile of the stars in the Galactic disk, close to the Galactic plane. We use a homogeneous sample of 34000 ultracool dwarfs M7 to L2.5 that all lie within 350 pc of the plane. We fit a profile of the form sech$^\alpha$, where $\alpha=2$ is the theoretically preferred isothermal profile and $\…
Spectroscopic and photometric analysis of the eclipsing binary HIP 7666 with δ Scuti pulsations
Esamdin, Ali; Wang, Liang; Cang, Tianqi +14 more
New multicolour photometric observations were carried out on 22 nights in three observation missions between 2015 October and 2016 February for eclipsing binary HIP 7666. High- and low-resolution spectroscopic observations were also carried out in the winters of 2015, 2016, and 2019, respectively. The fully phase-covered light curves and radial ve…
Multi-scale Radio and X-Ray Structure of the High-redshift Quasar PMN J0909+0354
Paragi, Zsolt; Frey, Sándor; Perger, Krisztina +3 more
The high-redshift quasar PMN J0909+0354 (z = 3.288) is known to have a parsec-scale compact jet structure, based on global 5 GHz very long baseline interferometry (VLBI) observations performed in 1992. Its kiloparsec-scale structure was studied with the Karl G. Jansky Very Large Array (VLA) in the radio and the Chandra space telescope in X-rays. A…
Further Adventures in Mars DTM Quality: Smoothing Errors, Sharpening Details
Kirk, R. L.; Gwinner, K.; Fergason, R. L. +4 more
We have used high-precision, high-resolution digital terrain models (DTMs) of the NASA Mars Science Laboratory and Mars 2020 rover landing sites based on mosaicked images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (MRO HiRISE) camera as a reference data set to evaluate DTMs based on Mars Express High Resolution…
Radio/X-ray correlations and variability in the X-ray binary LS I +61°303
Kraus, A.; Chernyakova, M.; Malyshev, D. +6 more
The high-mass X-ray binary LS I +61°303 exhibits variability in its radio and X-ray emissions, ranging from minute to hour time-scales. At such short time-scales, not much is known about the possible correlations between these two emissions from this source, which might offer hints to their origin. Here, we study the relationship between these emi…
Study of the Influence of an Evolving Galactic Potential on the Orbital Properties of 152 Globular Clusters with Data from the Gaia EDR3 Catalogue
Bobylev, V. V.; Bajkova, A. T.; Smirnov, A. A.
We have studied the influence of an evolving gravitational potential of the Milky Way Galaxy on the orbital motion of 152 globular clusters with proper motions from the Gaia EDR3 catalogue and mean distances from Baumgardt and Vasiliev (2021). To construct a semicosmological evolving model potential with changing masses and sizes of the Galactic c…
Swift/XRT Deep Galactic Plane Survey Discovery of a New Intermediate Polar Cataclysmic Variable, Swift J183920.1-045350
Göğüş, Ersin; Buckley, David; Kouveliotou, Chryssa +20 more
We report on the Swift/XRT Deep Galactic Plane Survey discovery and multiwavelength follow-up observations of a new intermediate polar (IP) cataclysmic variable, Swift J183920.1-045350. A 449.7 s spin period is found in XMM-Newton and NuSTAR data, accompanied by a 459.9 s optical period that is most likely the synodic, or beat period, produced fro…
Nearly 30,000 Late-type Main-sequence Stars with Stellar Age from LAMOST DR5
Zhao, Gang; Zhao, Jingkun; Ye, Xianhao +3 more
We construct a sample of nearly 30,000 main-sequence stars with 4500 K < Teff < 5000 K and stellar ages estimated by the chromospheric activity-age relation. This sample is used to determine the age distribution in the R-Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the heigh…
A new approximate coupling function: The case of Forbush decreases
Xaplanteris, L.; Livada, M.; Mavromichalaki, H. +1 more
We attempt the derivation of a new coupling function between ground level and primary cosmic rays for the case of Forbush decreases. The calculations for the new function are based on basic Quantum Field Theory theoretical tools, something that has not been attempted till now in other widely used cosmic ray coupling functions. The use of Quantum F…
Titan occultations of Orion's belt observed with Cassini/UVIS
Yelle, Roger V.; Koskinen, T. T.; Palmer, M. Y.
On 1 February 2016 Titan occulted the three stars in Orion's belt, as seen from the Casssini spacecraft. The ultraviolet spectrometer on Cassini observed this event with the stars arranged along the instrument's entrance slit. These three stellar occultations probed different latitudes in Titan's northern hemisphere but similar longitudes. The occ…