SZ Psc Research Articles

Swift and XMM–Newton observations of an RS CVn-type eclipsing binary SZ Psc: superflare and coronal properties

ABSTRACT We present an in-depth study of a large and long duration (>1.3 d) X-ray flare observed on an RS CVn-type eclipsing binary system SZ Psc using observations from Swift observatory. In the 0.35–10 keV energy band, the peak luminosity is estimated to be 4.2 × 1033 $\rm {erg}~\rm {s}^{-1}$. The quiescent corona of SZ Psc was observed ∼5.67 d after the flare using Swift observatory, and also ∼1.4 yr after the flare using the XMM–Newton satellite. The quiescent corona is found to consist of three temperature plasma: 4, 13, and 48 MK. High-resolution X-ray spectral analysis of the quiescent corona of SZ Psc suggests that the high first ionization potential (FIP) elements are more abundant than the low-FIP elements. The time-resolved X-ray spectroscopy of the flare shows a significant variation in the flare temperature, emission measure, and abundance. The peak values of temperature, emission measure, and abundances during the flare are estimated to be 199 ± 11 MK, 2.13 ± 0.05 × 1056 cm−3, 0.66 ± 0.09 $\rm {Z}_{\odot }$, respectively. Using the hydrodynamic loop modelling, we derive the loop length of the flare as 6.3 ± 0.5 × 1011 cm, whereas the loop pressure and density at the flare peak are derived to be 3.5 ± 0.7 × 103 dyn cm−2 and 8 ± 2 × 1010 cm−3, respectively. The total magnetic field to produce the flare is estimated to be 490 ± 60 G. The large magnetic field at the coronal height is supposed to be due to the presence of an extended convection zone of the subgiant and the high orbital velocity.

Prominence activation, optical flare, and post-flare loops on the RS Canum Venaticorum star SZ Piscium

We present the results of time-resolved high-resolution spectroscopic observations of the very active RS Canum Venaticorum (RS CVn) star SZ Piscium (SZ Psc), obtained during two consecutive observing nights on 2011 October 24 and 25. Several optical chromospheric activity indicators are analysed using the spectral subtraction technique, which show the remarkably different behaviour between two nights. Gradually blue-shifted and strengthened excess absorption features presented in the series of the subtracted spectra (especially for the H alpha, He I D-3, and H beta lines), as a result of active stellar prominence that is rising its height along the line of our sight, was detected in the observations on October 24. This prominence activation event was probably associated with the subsequently occurred optical flare, and part of that flare decay phase was hunted in the observations on October 25. The flare was characterized by the prominent He I D-3 line emission, as well as stronger chromospheric emission in the H alpha, H beta, and other active lines. The gradual decay of flare was accompanied by an obviously developmental absorption feature in the blue wing of the H alpha and other active lines, which could be explained as cool post-flare loops which projected against the bright flare background. Therefore, a series of possibly associated magnetic activity phenomena, including flare-related prominence activation, optical flare, and post-flare loops, were detected during our observations.

Large X-ray flares on stars detected with MAXI/GSC: A universal correlation between the duration of a flare and its X-ray luminosity

Abstract Twenty-three giant flares from thirteen active stars (eight RS CVn systems, one Algol system, three dMe stars, and one young stellar object) were detected during the first two years of our all-sky X-ray monitoring with the gas propotional counters (GSC) of the Monitor of All-sky X-ray Image (MAXI). The observed parameters of all these MAXI/GSC flares are found to be at the upper ends for stellar flares with the luminosity of 1031–34 erg s−1 in the 2–20 keV band, the emission measure of 1054–57 cm−3, the e-folding time of 1 hr to 1.5 d, and the total radiative energy released during the flare of 1034–39 erg. Notably, the peak X-ray luminosity of $5^{+4}_{-2} \times 10^{33}\:$erg s−1 in the 2–20 keV band was detected in one of the flares on II Peg, which is one of the, or potentially the, largest-ever-observed in stellar flares. X-ray flares were detected from GT Mus, V841 Cen, SZ Psc, and TWA-7 for the first time in this survey. Whereas most of our detected sources are multiple-star systems, two of them are single stars (YZ CMi and TWA-7). Among the stellar sources within 100 pc distance, the MAXI/GSC sources have larger rotation velocities than the other sources. This suggests that the rapid rotation velocity may play a key role in generating large flares. Combining the X-ray flare data of nearby stars and the sun, taken from literature and our own data, we discovered a universal correlation of $\tau \propto L_{\rm X}^{0.2}$ for the flare duration τ and the intrinsic X-ray luminosity LX in the 0.1–100 keV band, which holds for 5 and 12 orders of magnitude in τ and LX, respectively. The MAXI/GSC sample is located at the highest ends of the correlation.

The first Doppler images of the eclipsing binary SZ Piscium

We present the first Doppler images of the active eclipsing binary system SZ Psc, based on the high-resolution spectral data sets obtained in 2004 November and 2006 September--December. The least-squares deconvolution technique was applied to derive high signal-to-noise profiles from the observed spectra of SZ Psc. Absorption features contributed by a third component of the system were detected in the LSD profiles at all observed phases. We estimated the mass and period of the third component to be about $0.9 M_{\odot}$ and $1283 \pm 10$ d, respectively. After removing the contribution of the third body from the LSD profiles, we derived the surface maps of SZ Psc. The resulting Doppler images indicate significant starspot activities on the surface of the K subgiant component. The distributions of starspots are more complex than that revealed by previous photometric studies. The cooler K component exhibited pronounced high-latitude spots as well as numerous low- and intermediate-latitude spot groups during the entire observing seasons, but did not show any large, stable polar cap, different from many other active RS CVn-type binaries.

New observations of chromospheric and prominence activity on the RS CVn-type binary SZ Piscium

Aims. New high-resolution spectroscopic observations were made for the RS CVn-type binary SZ Psc aimed at searching for evidence of stellar prominences in this system and studying its chromospheric activity. Methods. By means of the spectral subtraction technique, we searched for prominence-like events in the H-alpha spectra, and also analyzed several optical chromospheric activity indicators (the He (I) D-3, Na (I) D-1, D-2, H-alpha, and Ca (II) IRT lines) included in our observations. Results. The emission in the H-alpha and Ca (II) IRT lines show that the cooler component is very active, supporting earlier work. Notably, some absorption features are detected in the subtracted H-alpha profiles, and one of them may result from prominence-like material on the cooler component of the system. According to a model of stellar prominences, the distance of the prominence from the rotation axis of the cooler component is calculated to be close to the corotation radius and to exceed the Roche lobe of the cooler component.

Orbital Period Change of the Eclipsing Binary System SZ Piscium

We collected and tabulated all available times of the light minimum of the eclipsing RS CVn-type binary system SZ Psc that we could find in the literature. The $O-C$ curve was constructed by means of a weighted least-squares method. It was found that a sinusoidal variation, with a period of 55.5 yr and an amplitude of 0.$^{\rm d}$2667, is superimposed on a long-term period decrease at a rate of $dP/dt = -$(2.7$\pm $0.2) $\times$ 10$^{-8} $days$/$day. Since one component of SZ Psc is a late-type star, which shows strong Ca II H & K emission lines, the orbital period variation may be caused by the magnetic activity of the system.

Chromospheric activity on the RS Canum Venaticorum binary SZ Piscium

Aims. We present the new high-resolution echelle spectra of SZ Psc, obtained in Nov. 2004 and Sep.- Dec. 2006, and study its chromospheric activity. Methods. By means of the spectral subtraction technique, we analyze our spectroscopic observations including several optical chromospheric activity indicators (the He I D(3), Na I D(1), D(2), H alpha, and Ca II infrared triplet lines). Results. All indicators show that the chromospheric activity of the system is associated with the cooler component. We find that the values of EW(8542)/EW(8498) are in the range 1-3, which indicates optically thick emission in plage-like regions. The 2006 data suggest the presence of active longitude phenomena. For the Ca II 8542 and 8662 and the Ha lines, it seems that the excess emission is stronger near the two quadratures of system. This may be anti-correlated with the behavior of the Na I D(1) line. The absorption features are detected in the subtracted Ha lines, which could be explained by prominence-like extended material seen on the stellar disk or by mass transfer from the cooler component to the hotter one.

Long-term magnetic activity in close binary systems

Aims.This is the first of a series of papers in which we present the results of a long-term photometric monitoring project carried out at Catania Astrophysical Observatory aimed at studying magnetic activity in late-type components of close binary systems, its dependence on global stellar parameters, and its evolution on different time scales from days to years. In this first paper, we present the complete observation dataset and new results of an investigation into the origin of brightness and color variations observed in the well-known magnetically active close binary stars: AR Psc, VY Ari, UX Ari, V711 Tau, EI Eri, V1149 Ori, DH Leo, HU Vir, RS CVn, V775 Her, AR Lac, SZ Psc, II Peg and BY Dra

The Distribution of Activity on the RS CVn–Type Star SZ Piscium

ABSTRACTWe use contemporaneous spectra and BV light curves to derive a model of the distribution of spots and active regions on the cooler component of SZ Psc for the 1993–1994 season. For that epoch, both spots and active regions were visible at all rotational phases of this chromospherically active star. The lack of large distortions of Doppler profiles of optical lines argues for ≳15 spots with angular radii of ≲8°–10°. Transition region emission was constant to within ±12% over the orbit, nor was it eclipsed appreciably. This leads us to estimate that there are at least 20 active regions, perhaps several hundred. Chromospheric Mg ii emission seems to have been proportional to the unspotted area of the star, not to the area of spots visible. We detected one strong flare in transition region lines during this program. We also present new light‐curve and radial velocity solutions. These solutions find the more massive, cool star very close to its Roche lobe, and the hot star rotating more slowly than synchronously, making SZ Psc an important system for tecent he structure and evolution of binary stars. Changes in the radial velocities over 2 years of subsequent monitoring show that SZ Psc is a triple system. Hα emission seems independent of phase on the average, but it can increase markedly for periods of a few orbital cycles.

Active Longitudes in Close Binaries

We examine the positions of the active longitudes in close binaries with respect to their companion stars on a sample of 12 systems. The primaries of four (five?) main sequence eclipsing binaries (RT And, CG Cyg, BH Vir, WY Cnc, and, possibly, UV Psc) show active longitudes at the quadrature positions. The K2 IV component of RS CVn has spots at all longitudes. Three subgiant binaries (AR Lac, SZ Psc and RT Lac have spots on both components, with pronounced active longitudes at the substellar points, and at other longitudes as well. Finally, three giant, non-eclipsing binaries (UZ Lib, HK Lac, IM Peg) have active longitudes at their substellar points and opposite to it. In case of main sequence systems probably their common magnetic field, for giants the tidal force, and, for subgiants both forces together, determine the positions of the active longitudes.

Chromospheric activity and unique solution of SZ Psc

We have confirmed that the Mg ii h and k emission lines of SZ Psc are mainly enhanced by the K subgiant component of the system, using the radial velocities reduced from the emission lines. The intensity variation of the emission line is correlated with the orbital phase of SZ Psc. The shape of light curves of SZ Psc were changing every season. The three representative light curves of three different epochs, 1978, 1979 and 1981, were selected to find a unique solution of SZ Psc which can explain the variation of light curves. The binary parameters, including inclination, mass ratio, temperatures and potentials of both components for the three epochs coincide, although the shapes of light curves for three epochs are different from each other. Changing only spot parameters, the model light curves fit to the observed light curves for three epochs. This means that the variation of spot location and size is the main reason for changing the shape of light curves.

New photometric study of the RS CVn type binarySZ Psc

Abstract Visual (BV) light curves of the RS CVn type binary system SZ Psc are presented. The light curves show a period change towards decreasing phases. New parameters for the system are found based on an analysis of the observed light curves using a Djuraŝevic's inverseproblem method. The observed light curves of SZ Psc, in both observational bands, can be successfully interpreted within the Roche model with three spotted areas on the surface of the more massive component. Characteristics of the spots and a genera discussion of the observed light curves and the results are given.

Spectropolarimetric observations of active stars

This paper reports the results of five years (five runs, 23 nights) of spectropolarimetric observations of active stars with the UCL Echelle Spectrograph of the Anglo-Australian Telescope. 225 circularly (and four linearly) polarized spectra were recorded on 28 objects (21 active stars and seven calibration standards) using the new technique of Zeeman-Doppler imaging. To extract polarization echelle spectra from raw frames, we developed a new dedicated automatic software package (called ESpRIT, which utilizes optimal extraction techniques) whose detailed description is given in the paper. For each recorded spectrum, we extract 'mean' polarized and unpolarized profiles using 'least-squares deconvolution', a technique similar to cross-correlation, which can enhance enormously the sensitivity of Zeeman-Doppler imaging, by up to 7.5 mag in flux with respect to a single average line analysis or by 4.5 mag compared with the older technique of Donati et al. in the particular case of a K1 star. Magnetic field is detected unambiguously on 14 objects, namely the weak-line T Tauri star V410 Tau, the pre-main-sequence binary HD 155555, the ZAMS stars AB Dor and LQ Hya, the dwarf flare star CC Eri, the RS CVn systems HR 1099, EI Eri, TY Pyx, CF Tue, SZ Psc, II Peg, IM Peg and IL Hya, and the FK Com star YY Men. Marginal field detections are also obtained for the weak-line T Tauri star HD 283572 and the Herbig Ae star HD 104237. Except on HR 1099 and II Peg, our results represent the first direct field detections ever reported on these objects, and in particular the first direct field detection on as young a star as V410 Tau. Most of the magnetic signatures we detect on cool stars show several sign reversals throughout the line profile, indicating that the parent field structure is rather complex and must feature (as expected) many small-scale magnetic regions of different polarities. For all stars on which Zeeman detections are recorded with sufficient accuracy (namely LQ Hya, CC Eri, HR 1099, El Eri, II Peg, IL Hya and YY Men), differential least-squares deconvolution from both the blue and the red parts of the spectral domain indicates that the magnetic regions we detect are mostly 500 to 1000 K cooler than, and sometimes at the same temperature as, but never warmer than the surrounding photosphere. Serendipitous results include the first detection (i) of small-amplitude radial velocity variations (1.3 kms -1 peak to peak) of the Herbig Ae star HD 104237 with small enough a period (37.5 ± 1 min) that they must be due to stellar pulsations and (ii) of the solar-like secondary component of the RS CVn system IL Hya.

The UV spectrum of the binary system SZ Psc

In this paper we study the far-UV as well as the UV spectrum of the spectroscopic binary system SZ Psc in the wavelength ranges λλ1235–1950 A and λλ2710–3090 A, respectively, from spectra obtained with the International Ultraviolet Explorer (IUE). The UV spectrum of SZ Psc is mainly an emission spectrum. The short wavelength region includes emission lines formed from the low chromosphere to the transition region (e.g., Siiv,Civ, andNv) and also a deep and broad absorption line of Feii.

Orbits of close binaries with CA II H and K in emission. II - Rediscussion of six systems with previously published orbits

Spectroscopic orbits, based on material of higher resolution than employed previously by others, are derived for the H and K emission binaries WW Dra, RZ Eri, MM Her, VV Mon, LX Per, and SZ Psc. For the eight systems, including RS Cvn and Z Her from Paper I (45.117.095), velocities of the hotter components are based on numerous absorption lines in the blue-violet spectrum. Only for the long-period system RZ Eri are reliable velocities obtained for the cooler components from absorption lines in this region, and recourse is had to Ca II emission and to absorption lines in the visual region of the spectrum. Difficulties with velocities from the emission lines and from the Na D absorption lines are discussed.

Analysis of activity indicators in two RS CVn systems

In order to contribute to the understanding of the activity phenomena in late-type stars, we have obtained new CaII H and K emission line fluxes and equivalent widths for two RS CVn binaries, namely LX Per and SZ Psc, observed in several orbital phases. Both systems show a large activity and a flare-like phenomenon has been detected in SZ Psc.

Dual polarization VLBI observations of stellar binary systems at 5 GHz

The binary systems Sigma CrB, SZ Psc, HR 1099, UX Ari, HR 5110, Algol, and Cyg X-1 are characterized in terms of marcsec-scale radio structure on the basis of dual-polarization observations at 4.969-4.997 GHz, obtained with an international VLBI array comprising the 100-m Effelsberg, 36-m Haystack, 42-m Green Bank, 26-m Fort Davis, 130-m-equivalent VLA, and 40-m Owens Valley telescopes (system temperatures 40-70 K) at 22-14 h UT on July 26-27, 1983. The data are presented in graphs and tables and discussed in detail. Single Gaussian brightness distributions with theta(FWHM) = 0.5-2.0 marcsec and brightness temperatures (2-200) x 10 to the 8th K are determined for four sources; core-halo structures are found for UX Ari and Algol; and an upper limit of 50 microarcsec is established for the angular separation of the regions of left and right circular polarization. The gross features seen in RS CVn systems are explained in terms of a simple expanding-coronal-loop model of flare events.

Hydrogen-alpha observations of RS Canum Venaticorum stars. III - The eclipsing systems AR Lacertae and SZ PISCIUM

view Abstract Citations (32) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hydrogen-alpha observations of RS Canum Venaticorum stars. III. The eclipsing systems AR Lacertae and SZ Piscium. Huenemoerder, D. P. ; Ramsey, L. W. Abstract The authors have spectroscopically monitored two eclipsing double-lined RS CVn binaries, AR Lacertae and SZ Piscium, over many orbital periods at the wavelength of Hα. Excess Hα emission profiles were derived by subtracting composite comparison spectra synthesized from observations of single inactive stars. AR Lac showed no excess Hα emission. SZ Psc was highly active with emission from the cooler stellar component. SZ Psc also underwent a large Hα outburst during and after which profiles were suggestive of a circumstellar origin. Publication: The Astronomical Journal Pub Date: April 1984 DOI: 10.1086/113547 Bibcode: 1984AJ.....89..549H Keywords: Eclipsing Binary Stars; H Alpha Line; Stellar Spectrophotometry; Emission Spectra; Solar Flares; Spectral Energy Distribution; Stellar Envelopes; Stellar Rotation; Stellar Temperature; Temporal Distribution; Astrophysics full text sources ADS | data products SIMBAD (3) Related Materials (2) Part 1: 1984AJ.....89..115R Part 3: 1985AJ.....90..499H

Two-colour photoelectric investigation of SZ Pisces

The RS CVn-type eclipsing binary SZ Psc was observed in two coloursB andV, in 1981. The rate of change of the period was calculated using two different least-squares procedures. The amplitudes of the light variations at outside eclipses are 0 . m 181 and 0 . m 213 inB andV colours, respectively. The light curves of the system have been solved using a new approximation. The radius of the cooler component is only 82% of its Roche-radius and the system is detached one.

V388 Cygni: a binary system in the rapid phase of mass exchange?

Using the Wilson & Devinney approach, we analyse the only existing, as far as we know, photoelectric lightcurve of V388 Cyg (P = 0.859 day, Sp = A3). The absence of any spectroscopic indication of the mass ratio was overcome by the computation of a grid of solutions with many values of q = ℳc/ℳh which fixed a well-determined range of possible q's. For every possible value of q, the primary (more massive and hotter) component fills its lobe, while the secondary, although detached, is not far from contact. It is suggested that V388 Cyg is a semi-detached system in the rapid phase of case A mass exchange, like SZ Psc and BF Aur. This possibility is discussed, taking into account the observed period variations as well. Although only spectroscopic information may solve the problem of the evolutionary stage of V388 Cyg, we find that the inferred configuration is at least very probable and that no evidence exists against it.