Search Publications
Revealing two radio-active galactic nuclei extremely near PSR J0437-4715
Paragi, Zsolt; Wang, Jiancheng; Yang, Jun +9 more
Newton's gravitational constant G may vary with time at an extremely low level. The time variability of G will affect the orbital motion of a millisecond pulsar in a binary system and cause a tiny difference between the orbital period-dependent measurement of the kinematic distance and the direct measurement of the annual parallax distance. PSR J0…
X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Trianguli
Schmitt, J. H. M. M.; Czesla, S.; Robrade, J. +2 more
Context.Close binary systems provide an excellent tool for determining stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most of these systems exhibit strong signs of magnetic activity, postulated to be the underlying reason for radius inflation in many of the components. Aims.We ex…
The possible common origin of M 16 and M 17
Comerón, F.; Torra, J.
Context. It has been suggested that the well-studied giant HII regions M 16 and M 17 may have had a common origin, being an example of large-scale triggered star formation. While some features of the distribution of the interstellar medium in the region support this interpretation, no definitive detection of an earlier population of massive stars …
A long serendipitous XMM-Newton observation of the intermediate polar XY Ari1
Burwitz, V.; Balman, Ş.; Zengin Ćamurdan, D.
XY Ari is one of the few known eclipsing intermediate polars. We present results from a detailed analysis of an unpublished archival observation using XMM-Newton EPIC pn and MOS data in a quiescent state of XY Ari. The X-ray orbital modulation and spin-pulse variations were investigated for energy-dependent modulations in different energy bands. T…
A Chandra X-ray census of the interacting binaries in old open clusters - NGC 188
Wijnands, Rudy; van den Berg, Maureen; Vats, Smriti
We present a new X-ray study of NGC 188, one of the oldest open clusters known in our Galaxy (7 Gyr). Our observation with the Chandra X-ray Observatory is aimed at uncovering the population of close interacting binaries in NGC 188. We detect 84 sources down to a luminosity of LX ≈ 4 × 1029 erg s-1 (0.3-7 keV), of …
The Nature of Variations in Anomalies of the Chemical Composition of the Solar Corona with the 11-Year Cycle
Pipin, V. V.; Tomozov, V. M.
Evidence that the distribution of the abundances of admixtures with low first-ionization potentials (FIP < 10 eV) in the lower solar corona could be associated with the typology of the largescale magnetic field is presented. Solar observations show an enhancement in the abundances of elements with low FIPs compared to elements with high FIPs (&…
Formation of Large-scale Coronal Loops Interconnecting Two Active Regions through Gradual Magnetic Reconnection and an Associated Heating Process
Liu, Chang; Wang, Haimin; Chen, Yao +5 more
Coronal loops interconnecting two active regions (ARs), called interconnecting loops (ILs), are prominent large-scale structures in the solar atmosphere. They carry a significant amount of magnetic flux and therefore are considered to be an important element of the solar dynamo process. Earlier observations showed that eruptions of ILs are an impo…
On the Distance Measurements in the Thin Milky Way Disk
Krełowski, J.; Galazutdinov, G. A.; Strobel, A. +2 more
We present a test how far the direct, trigonometric parallax measurements and those, based on interstellar CaII H and K lines lead to distances to OB stars similar to those, based on spectrophotometrically determined ones. For this we use relatively nearby objects where the extinction effects are negligible. A test is based on observations of inte…
Limits on Dione's Activity Using Cassini/CIRS Data
Spencer, John R.; Howett, Carly J. A.; Hurford, Terry +2 more
We use nighttime Cassini Composite Infrared Spectrometer (CIRS) data to look for discrete regions of elevated nighttime temperatures indicative of endogenic activity on Dione's surface. This is achieved by producing low latitude and midlatitude (less than 60°) maps of Dione's nighttime surface temperature, derived from 10 to 1,100-cm-1 …
Determining the accuracy of VLBI radio source catalogs
Liu, N.; Zhu, Z.; Lambert, S. B.
Aims: We propose to estimate the accuracy of current very long baseline interferometry (VLBI) catalogs.
Methods: The difference of source position estimated from two decimation solutions was analyzed to estimate the scale factor and noise floor for the formal error of radio source positions by two different methods. In one method, we inv…