We present and discuss the results of our photometric and spectroscopic monitoring of 2SXPS J173508.4-292958 carried out from April to August 2020. This X-ray source, in the foreground with respect to the Galactic center, brightened in X-rays during 2020, prompting our follow-up optical observations. We found the star to contain a K4III giant with a modest but highly variable Halpha emission, composed by a ~470 km/s wide component with superimposed a narrow absorption, offset by a positive velocity with respect to the giant. No orbital motion is detected for the K4III, showing an heliocentric radial velocity stable at -12(+/-1) km/s. No flickering in excess of 0.005 mag in B band was observed at three separate visits of 2SXPS J173508.4-292958. While photometrically stable in 2016 through 2018, in 2019 the star developed a limited photometric variability, that in 2020 took the form of a sinusoidal modulation with a period of 38 days and an amplitude of 0.12 mag in V band. We argue this variability cannot be ascribed to Roche-lobe filling by the K4III star. No correlation is observed between the photometric variability and the amount of emission in Halpha, the latter probably originating directly from the accretion disk around the accreting companion. While no emission from dust is detected at mid-IR wavelengths, an excess in U-band is probably present and caused by direct emission from the accretion disk. We conclude that 2SXPS J173508.4-292958 is a new symbiotic star of the accreting-only variety (AO-SySt).
We present new multicolour (UBVRcIc) photometric observations of classical symbiotic stars, EG And, Z And, BF Cyg, CH Cyg, CI Cyg, V1329 Cyg, TX CVn, AG Dra, Draco C1, AG Peg and AX Per, carried out between 2007.1 and 2011.9. The aim of this paper is to present new data of our monitoring programme, to describe the main features of their light curves and to point problems for their future investigation. The data were obtained by the method of the classical photoelectric and CCD photometry.
We present new multicolour UBVRcIc photometric observations of symbiotic stars, EG And, Z And, BF Cyg, CH Cyg, CI Cyg, V1016 Cyg, V1329 Cyg, AG Dra, RS Oph, AG Peg, AX Per, and the newly discovered (August 2018) symbiotic star HBHA 1704-05, we carried out during the period from 2011.9 to 2018.75. Historical photographic and visual/V data were collected for HBHA 1704-05, FG Ser and AE Ara, AR Pav, respectively. The main aim of this paper is to present our original observations of symbiotic stars and to describe the most interesting features of their light curves. For example, periodic variation…
We present time-series CCD photometry in the $BVRI$ passbands of the recently identified symbiotic nova V1835 Aquilae (NSV 11749) over an interval of 5.1 years with 7-14 day cadence, observed during its quiescence. We find slow light variations with a range of $\sim$0.9 mag in $V$ and $\sim$0.3 mag in $I$. Analysis of these data show strong periodicity at $419 \pm 10$ days, which we interpret to be the system's orbital period. A dip in the otherwise-sinusoidal phased light curve suggests a weak ellipsoidal effect due to tidal distortion of the giant star, which in turn opens the possibility th…
MACHO project photometry shows the candidate Symbiotic Star V5485 Sagittarii's red giant component has a photometric orbital period of 270 days as evidenced by ellipsoidal variation of the lightcurve.
AG Dra is a well known bright symbiotic binary with a white dwarf and a pulsating red giant. The long-term photometry monitoring and a new behaviour of the system are presented. The detailed period analysis of photometry as well as spectroscopy was carried out. In the system of AG Dra, two periods of variability are detected. The longer one around 550 days is related to the orbital motion, and the shorter one around 355 days is interpreted as pulsations of the red giant in our older paper. In addition the active stages change distinctively, but the outbursts are repeated with the periods from …
The symbiotic star AG Dra experienced a double-peaked outburst of 0.6 magnitudes in April and May 2016. Photometry and spectroscopy through the outburst showed the B-V colour index varying linearly with the V magnitude and enabled the temperature variation of the hot star to be calculated from the changing flux in the H beta and He II 4686A emission lines.
FBS0107-082 is an emission line object previously classified as a nova-like cataclysmic variable star. New optical spectroscopy shows very strong hydrogen Balmer lines, along with a nebular forbidden line spectrum and absorption features from an early-F photosphere. When combined with other IR and optical data from the literature, these data point to the object being a symbiotic nova seen in a prolonged outburst. Photometry on time scales of minutes, days, and years show only very weak variability.
We analyse long-term optical photometry for two Galactic recurrent novae (V745 Sco and V3890 Sgr) and one Large Magellanic Cloud object (Nova LMC 1990b) observed over several years by the Optical Gravitational Lensing Experiment (OGLE) sky survey. We do not find variability with the previously claimed orbital period of V745 Sco. This voids previous findings based on this value (e.g. the distance determination). The quiescence variability of this object is dominated by semiregular pulsations of the red giant secondary (with periods of 136.5 and 77.4 d). The photometry of Nova LMC 1990b reveals …
We aimed to verify the nature and derive the basic parameters of the symbiotic star candidate [JD2002] 11. For this purpose, we obtained and analysed an X-Shooter spectrum of [JD2002] 11. We also used optical and infrared photometry available for the object. Emission-line diagnostic ratios are characteristic of a dusty type symbiotic star and reveal a two-component nebula (low- and high-density). The spectral energy distribution is well fitted with a two-component blackbody spectrum with the respective temperatures of 1150 K and 600 K. The total luminosity of $\rm 3000\,L_{\odot}$ is consisten…
We present UBVRI photometry of three symbiotic stars ZZ CMi, TX CVn and AG Peg carried out from 1997 to 2008 in Piwnice Observatory near Torun. To search orbital periods of these stars Fourier analysis was used. For two of them, TX CVn and AG Peg, we have confirmed the earlier known periods. For ZZ CMi we found a relatively short period 218.59 days. Assuming, that the orbital period is twice longer (P=437.18 days), the double sine wave in the light curve can be interpreted by ellipsoidal effect.
We report finding high-velocity components in the Hα emission wings of St 2-22 spectra, obtained in 2005. This discovery have encouraged us to start the present study, aiming to show that this little studied object is a jet producing symbiotic system. We used high-resolution optical and low-resolution near infrared spectra, as well as available optical and infrared photometry, to evaluate some of the physical parameters of the St 2-22 components and the characteristics of the jets. The evaluated parameters of the components confirmed that St 2-22 is a S-type symbiotic star. Our results demonst…
V2756 Sgr is a long-known S-type symbiotic binary that was recently detected in $\sim$ 1 mag eclipse-like fading by the Gaia satellite. This behavior was reported as a Gaia Science Alert under the designation Gaia22eor. V2756 Sgr has not been reported as an eclipsing symbiotic system. In this contribution, we have investigated the recent light curves of this target obtained by Gaia and ASAS-SN survey and supplemented these data by the photometry from the ASAS survey and DASCH archive. In addition, low-resolution BP/RP spectra from Gaia were examined. Based on the presented analysis, we conclud…
A search for new symbiotic stars in the Milky Way: Using machine learning techniques applied to photometric databases
Universidad de La Serena（拉塞雷纳大学）；Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama（阿塔卡马大学天文与行星科学研究所）；Millennium Institute of Astrophysics (MAS)（天体物理千年研究所）；Gemini Observatory/NSF’s NOIRLab（吉米尼观测站/美国国家光学红外天文实验室）；Universidad Nacional de Hurlingham (UNAHUR)（乌尔里汉国立大学）；Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)（国家科学研究委员会）
We report optical CCD photometry of the recently identified symbiotic star EF Aql. Our observations in Johnson V and B bands clearly show the presence of stochastic light variations with an amplitude of about 0.2 mag on a time scale of minutes. The observations point toward a white dwarf (WD) as the hot component in the system. It is the 11-th object among more than 200 symbiotic stars known with detected optical flickering. Estimates of the mass accretion rate onto the WD and the mass loss rate in the wind of the Mira secondary star lead to the conclusion that less than 1 per cent of the wind…
In this work, we present the discovery and characterization of a new southern S-type symbiotic star, DeGaPe 35. We have obtained the low-resolution spectroscopic observations and supplemented them with photometry from Gaia DR3 and other surveys. The optical spectra of this target show prominent emission lines, including highly ionized [Fe VII] and O VI lines. The cool component of this symbiotic binary is an M4-5 giant with effective temperature ~ 3 380 - 3 470 K and luminosity ~ 3 000 L$_\odot$ (for the adopted distance of 3 kpc). The hot component is a shell-burning white dwarf. The photomet…
We performed photometry with a 1 minute time resolution of the symbiotic stars EF Aquilae, AG Pegasi and SU Lyncis in Johnson B and V band. Our observations of the symbiotic Mira-type star EF Aql demonstrate the presence of stochastic light variations with an amplitude of about 0.25 magnitudes on a time scale of 5 minutes. The observations prove the white dwarf nature of the hot component in the binary system. It is the 11th symbiotic star (among more than 200 symbiotic stars known in our Galaxy) which displays optical flickering. For SU Lyn we do not detect flickering with an amplitude above …
New Online Database of Symbiotic Variables includes several poorly characterised objects and candidate symbiotic stars, not only in the Milky Way but also in other galaxies. The goal of the research presented in this paper was to reveal the nature of 2MASS J07363415+6538548, the object discovered as an X-ray source in the field of NGC 2403, and tentatively classified as a symbiotic candidate or a cataclysmic variable. By analysis of available photometric data from ground-based surveys, together with high precision photometry from TESS, remarkable astrometric measurements of the Gaia satellite,…
Highly bipolar planetary nebula Hen 2-57 and its possible symbiotic core
Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文学中心）；Astronomical Observatory, University of Warsaw（华沙大学天文台）
本文通过多波段观测分析高度双极天体 Hen 2-57，发现其具有沙漏形态、中红外过剩及中心核共生星特征，提出其由尘埃包裹的D型共生中央引擎塑造双极星云，是M 2-9的类似体。
Symbiotic stars are the longest orbital period interacting binaries, where nova-like outbursts are generated by the accretion of a high mass loss rate red giant wind onto a white dwarf companion. Long-term photometric monitoring surveys such as OGLE and MACHO are ideal platforms to identify nova-like events in symbiotic stars, however there are only a handful of known systems within the small footprint of these surveys. We introduce a systematic Halpha emission line object survey for new symbiotic stars covering 35 deg^2 towards the Galactic Bulge that combines deep 2dF/AAOmega spectroscopy wi…
Symbiotic binaries in the Gaia data. II. Symbiotic candidates from general variability classification in DR3
Charles University（查理大学）；Astronomical Institute, Faculty of Mathematics and Physics, Charles University（查理大学数学物理学院天文研究所）；Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Universidad de La Laguna（拉古纳大学）；Southern Spectroscopic Project Observatory Team (2SPOT)（南方光谱计划观测团队（2SPOT））；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文学中心）
We analyze $\sim$32 years of optical spectra and photometry for the symbiotic binary PU Vul. Light curves for the He I $λ$4471, He II $λ$4686 and H$β$ $λ$4861 emission lines reveal an illumination effect, where the hot white dwarf ionizes the outflowing wind of the red giant, and evidence for an eccentric orbit with e $\approx$ 0.16. Along with the gradual appearance of high ionization emission from [Fe VII] and O VI, the relative fluxes of these lines suggest an increase in the effective temperature of the hot component, from roughly $10^5$ K on JD 2448000 (1990) to roughly $2\times 10^5$ K o…
Hen 3-160 is reported in Belczynski et al.'s (2000) catalog as a symbiotic binary system with M7 giant donor. Using $V$- and $I$-band photometry collected over 20 years we have found that the giant is a Mira variable pulsating with 242.5-day period. The period-luminosity relation locates Hen 3-160 at the distance of about 9.4 kpc, and its Galactic coordinates ($l=267.7^{\circ}$, $b=-7.9^{\circ}$) place it $\sim$1.3 kpc above the disc. This position combined with relatively high proper motions (pm$_{\rm{RA}}=-1.5$ mas yr$^{-1}$, pm$_{\rm{DEC}}=+2.9$ mas yr$^{-1}$, Gaia DR2) indicates that Hen 3…
Pre-outburst 2MASS and WISE photometry of Nova Sco 2014 (V1534 Sco) have suggested the presence of a cool giant at the location of the nova in the sky. The spectral evolution recorded for the nova did not however support a direct partnership because no flash-ionized wind and no deceleration of the ejecta were observed, contrary to the behavior displayed by other novae which erupted within symbiotic binaries like V407 Cyg or RS Oph. We have therefore obtained an 0.8-2.5 micron spectra of the remnant of Nova Sco 2014 in order to ascertain if a cool giant is indeed present and if it is physically…
Accurate BVRI optical photometry of StHa 169 has been collected during the period 2005-2016. It reveals two outbursts, in 2009 and 2016, both peaking at B=13.6. The mean brightness in quiescence was B=15.29. In response to the 2016 outburst, the integrated absolute flux of the emission lines increased by a factor of 7 for Balmer, 9 for HeI lines, and 4.5 for HeII 4686, the Balmer continuum turned into strong emission, and [NeV] 3526 and OVI Raman 6825 Ang emissions disappeared. We have reconstructed the 1897-1951 B-band lightcurve of StHa 169 from Harvard historical plates. On top of a slow de…
We are performing a search for symbiotic stars using IPHAS, the INT Halpha survey of the northern Galactic plane, and follow-up observations. Candidate symbiotic stars are selected on the basis of their IPHAS and near-IR colours, and spectroscopy and photometry are obtained to determine their nature. We present here observations of the symbiotic star candidate IPHAS J205836.43+503307.2. The optical spectrum shows the combination of a number of emission lines, among which are the high-excitation species of [OIII], HeII, [Ca V], and [Fe VII], and a red continuum with the features of a star at th…
Theoretical predictions of the population of Galactic symbiotic stars (SySts) are highly inconsistent with the current known population. Despite intense effort over the past decades, observations are still far below the predictions. The majority of known SySts so far are identified based on selection criteria established in the optical regime. The recent discovery of SU Lyn with very faint optical emission lines uncloaked a subgroup of SySts with accreting-only white dwarfs. In this particular case, the luminous red giant may overshadow the dimmed white dwarf companion. A new approach to searc…
LAMOST J202629.80+423652.0 has been recently classified as a new symbiotic star containing a long-period Mira, surrounded by dust (D-type) and displaying in the optical spectra high ionization emission lines, including the Raman-scattered OVI at 6825 Ang. We have observed LAMOST J202629.80+423652.0 photometrically in the BVRI bands and spectroscopically over the 3500-8000 Ang range. We have found it to be a normal G8IV sub-giant star, deprived of any emission line in its spectrum, and reddened by E(B-V)=0.35 mag. Combining our photometry with data from all-sky patrol surveys, we find LAMOST J2…
Compared to mass transfer in cataclysmic variables, the nature of accretion in symbiotic binaries in which red giants transfer material to white dwarfs (WDs) has been difficult to uncover. The accretion flows in a symbiotic binary are most clearly observable, however, when there is no quasi-steady shell burning on the WD to hide them. RT Cru is the prototype of such non-burning symbiotics, with its hard (δ-type) X-ray emission providing a view of its innermost accretion structures. In the past 20 yr, RT Cru has experienced two similar optical brightening events, separated by 4000 days and with…
We here report on multiwavelength (X-ray to optical) followup observations of carbon star CGCS 5926. These were motivated by the fact that this star is positionally coincident with a faint X-ray emitting object belonging to the ROSAT catalog of sources, thus suggesting a possible symbiotic X-ray binary (SyXB) nature for it. Our spectrophotometric optical data confirm the giant carbon star nature of the object and allow us to classify its spectral type as C(6,2). This classification places CGCS 5926 at a distance of about 5 kpc from Earth. BVRcIc photometry of the star shows that it displays a …
Searching for outbursts from Symbiotic Binaries in GOTO and ATLAS data
Armagh Observatory & Planetarium（阿马赫天文台与天文馆）；University of Warwick（华威大学）；Monash University（莫纳什大学）；University of Sheffield（谢菲尔德大学）；University of Cambridge（剑桥大学）；University College Cork（科克大学）；The Open University（开放大学）；Radboud University（拉德堡德大学）；University of Manchester（曼彻斯特大学）
Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of nine white dwarf symbiotics that were not previously known to be X-ray sources and one that had previously been detected as a supersoft X-ray source. The nine new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. The Swift/XRT telescope detected all of the …
Besides the astrometric mission of the Gaia satellite, its repeated and high-precision measurements serve also as an all-sky photometric transient survey. The sudden brightenings of the sources are published as Gaia Photometric Science Alerts and are made publicly available allowing the community to photometrically and spectroscopically follow-up the object. The goal of this paper was to analyze the nature and derive the basic parameters of Gaia18aen, transient detected at the beginning of 2018. It coincides with the position of the emission line star WRAY 15-136. The brightening was classifie…
After 26 years from the major event of 1990, in early 2016 the puzzling symbiotic binary MWC 560 has gone into a new and even brighter outburst. We present our tight BVRI photometric monitoring of MWC 560 (451 independent runs distributed over 357 different nights), covering the 2005-2016 interval, and the current outburst in particoular. A stricking feature of the 2016 outburst has been the suppression of the short term chaotic variability during the rise toward maximum brightness, and its dominance afterward with an amplitude in excess of 0.5 mag. Similar to the 1990 event when the object re…
Symbiotic binaries sometimes hide their symbiotic nature for significant periods of time. There is mounting observational evidence that in those symbiotics that are powered solely by accretion of red-giant's wind material onto a white dwarf, without any quasi-steady shell burning on the surface of the white dwarf, the characteristic emission lines in the optical spectrum can vanish, leaving the semblance of an isolated red giant spectrum. Here we present compelling evidence that this disappearance of optical emission lines from the spectrum of RT Cru during 2019 was due to a decrease in the ac…
The VISTA Magellanic Cloud (VMC) survey is assembling a deep, multi-epoch atlas of YJKs photometry across the Magellanic Clouds. Prior to the VMC survey only the brightest Magellanic Cloud PNe (MCPNe) were accessible at near-infrared (NIR) wavelengths. It is now possible for the first time to assemble the NIR properties of MCPNe and to identify contaminating non-PNe mimics which are best revealed at NIR wavelengths (e.g. HII regions and symbiotic stars). To maintain the unique scientific niche that MCPNe occupy these contaminants must be removed. Here we conduct a VMC-led, multi-wavelength stu…
The star V426 Sge (HBHA~1704-05), originally classified as an emission-line object and a semi-regular variable, brightened at the beginning of August 2018, showing signatures of a symbiotic star outburst. We aim to confirm the nature of V426 Sge as a classical symbiotic star, determine the photometric ephemeris of the light minima, and suggest the path from its 1968 symbiotic nova outburst to the following 2018 Z And-type outburst. We re-constructed an historical light curve (LC) of V426 Sge from approximately the year 1900, and used original low- and high-resolution spectroscopy complemented …
We report on the discovery of large-amplitude flickering from V648 Car (= SS73-17), a poorly studied object listed amongst the very few hard X-ray emitting symbiotic stars. We performed milli-magnitude precision optical photometry with the Swope Telescope at the Las Campanas Observatory, Chile, and found that V648 Car shows large U-band variability over time scales of minutes. To our knowledge, it is amongst the largest flickering of a symbiotic star ever reported. Our finding supports the hypothesis that symbiotic WDs producing hard X-rays are predominantly powered by accretion, rather than q…
Millimeter-wave Detections of Symbiotic Stars in SPT and ACT Data
University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Princeton University（普林斯顿大学）；Texas Tech University（德克萨斯理工大学）；Fermi National Accelerator Laboratory（费米国家加速器实验室）
Only one carbon-rich (C-rich, hereinafter) Mira variable has so far been suggested as a member of the Galactic bulge and this is in a symbiotic system. Here we describe a method for selecting C-rich candidates from an infrared colour-colour diagram, (J-Ks) vs ([9]-[18]). Follow-up low-resolution spectroscopy resulted in the detection of 8 C-rich Mira variables from a sample of36 candidates towards the Galactic bulge. Our near-infrared photometry indicates that two of these, including the known symbiotic, are closer than the main body of the bulge while a third is a known foreground object. Of …
Symbiotic stars in which the symbiotic phenomenon is powered solely by accretion, often at an average rate that is higher than in cataclysmic variable stars, provide an important opportunity to diagnose boundary layers around disk-accreting white dwarfs. Here we investigate SU Lyncis, a recently discovered example of a purely accretion-powered symbiotic star, using the first reliable X-ray spectroscopy, obtained with NuSTAR, and UV photometry obtained with Swift. SU Lyn has hard, thermal, X-ray emission that is strongly affected by a variable local absorber - that has little impact on the UV e…
We present photometric and spectroscopic follow-up observations of short-period variables discovered in the OmegaWhite survey: a wide-field high-cadence g-band synoptic survey targeting the Galactic Plane. We have used fast photometry on the SAAO 1.0-m and 1.9-m telescopes to obtain light curves of 27 variables, and use these results to validate the period and amplitude estimates from the OmegaWhite processing pipeline. Furthermore, 57 sources (44 unique, 13 also with new light curves) were selected for spectroscopic follow-up using either the SAAO 1.9-m telescope or the Southern African Large…
Variability of Central Stars of Planetary Nebulae with the Zwicky Transient Facility. I. Methods, Short-Timescale Variables, Binary Candidates, and the Unusual Nucleus of WeSb 1
