- ID:
- ivo://CDS.VizieR/J/A+A/511/A63
- Title:
- V1118 Ori UBVRIJHK outburst light curves
- Short Name:
- J/A+A/511/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The accretion history of low-mass young stars is not smooth but shows spikes of accretion that can last from months and years to decades and centuries. Observations of young stars in outbursts can help us understand the temporal evolution of accreting stars and the interplay between the accretion disk and the stellar magnetosphere. The young late-type star V1118 Orionis was in outburst from 2005 to 2006. We followed the outburst with optical and near-infrared photometry. The X-ray emission was further probed with observations taken with XMM-Newton and Chandra during and after the outburst. In addition, we obtained mid-infrared photometry and spectroscopy with Spitzer at the peak of the outburst and in the post-outburst phase. The spectral energy distribution of V1118 Ori varied significantly over the course of the outburst. The optical flux showed the largest variations, most likely caused by enhanced emission by a hot spot. The hot spot dominated the optical and near-infrared emission at the peak of the outburst, while the disk emission dominated in the mid-infrared. The emission silicate feature in V1118 Ori is flat and does not vary in shape, but was slightly brighter at the peak of the outburst compared to the post-outburst spectrum. The X-ray flux correlated with the optical and infrared fluxes, indicating that accretion affected the magnetically active corona and the stellar magnetosphere. The thermal structure of the corona was variable with some indication of a cooling of the coronal temperature in the early phase of the outburst with a gradual return to normal values. Color-color diagrams in the optical and infrared showed variations during the outburst, with no obvious signature of reddening caused by circumstellar matter. Using Monte-Carlo realizations of star+disk+hotspot models to fit the spectral energy distributions in "quiescence" and at the peak of the outburst, we determined that the mass accretion rate varied from about 2.5x10^-7^M_{sun}_/yr to 1.0x10^-6^M_{sun}_/yr; in addition, the fractional area of the hotspot increased significantly. The multi-wavelength study of the V1118 Ori outburst helped us to understand the variations in spectral energy distributions and demonstrated the interplay between the disk and the stellar magnetosphere in a young, strongly accreting star.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/337/183
- Title:
- V1046 Ori uvby photometry and radial velocities
- Short Name:
- J/A+A/337/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a detailed spectroscopic and photometric study of V1046 Orionis undertaken to resolve uncertainties about the period(s) and causes of the spectroscopic and photometric variations of this helium-strong star. We have detected the lines of the secondary star in an extensive series of photographic and electronic spectra. This eliminates any doubt about the duplicity of this star. The orbital elements we derive from our measures of these spectra confirm the unusually large orbital eccentricity, e=0.433, for the short, P=18.65612d, orbital period. The line profiles, V/R ratio of the double H{alpha} emission, residuals of the primary radial velocities from the orbital velocity curve, brightness and colour of the object, magnetic field, and radio emission of this system all vary with a period of 0.9011836d. We tentatively follow earlier investigators in interpreting this as the rotational period of the primary and summarize the evidence of the phase shifts among the different phenomena, using the accurate value of the 0.9d period, to put tight constraints on any future model of these changes. We postpone our own attempt at a quantitative modelling of the variations with the 0.9d period for a separate study.
- ID:
- ivo://CDS.VizieR/J/AJ/161/102
- Title:
- VPDs and CMDs of Berkeley32, Berkeley98 and King23
- Short Name:
- J/AJ/161/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the photometric and kinematical data from Gaia Data Release 2, three old open clusters namely Berkeley32 (Be32), Berkeley98 (Be98), and King23 are investigated. The latter two of these clusters are poorly studied in the literature. The numbers of the most probable cluster members are 563, 260, and 114 for Be32, Be98, and King23, respectively, with membership probabilities higher than 80% and lying within the clusters limiting radii. Mean proper motions (PMs; {mu}_{alpha}_cos_{delta}_ and {mu}_{delta}_) of the clusters are determined as (-0.34{+/-}0.008, -1.60{+/-}0.006), (-1.34{+/-}0.007, -3.22{+/-}0.008), and (-0.46{+/-}0.009, -0.87{+/-}0.012)mas/yr. The errors mentioned in the PMs are the Gaussian fitting errors. The blue straggler stars (BSS) in all three old clusters were found to exhibit centralized radial distribution. The clusters' radii are determined as 9.4', 12.95', and 6.6' for Be32, Be98, and King23 using radial density profiles. Ages of the clusters determined by isochrone fitting are 4.90{+/-}0.22, 3.23{+/-}0.15, and 1.95{+/-}0.22Gyr. The errors given in the clusters ages are the internal errors. The mass function slopes are found to be flatter than Salpeter's value for all three clusters. All three clusters are found to be dynamically relaxed. Galactic orbits are derived for these clusters, which demonstrate that the studied clusters follow a circular path around the Galactic center.
4554. V505 Per BV light curves
- ID:
- ivo://CDS.VizieR/J/A+A/480/465
- Title:
- V505 Per BV light curves
- Short Name:
- J/A+A/480/465
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The orbit and fundamental physical parameters of the double-lined eclipsing binary V505 Per are derived by means of Echelle high-resolution and high S/N spectroscopy, and B, V photometry. In addition, effective temperatures, gravities, rotational velocities, and metallicities of both components are also obtained from atmospheric chi^2^ analysis, showing an excellent match with the results of the orbital solution.
- ID:
- ivo://CDS.VizieR/J/other/NewA/36.50
- Title:
- V873 Per BVR light curves
- Short Name:
- J/other/NewA/36.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric study of a weak-contact binary V873 Per. New observations in BVR filter bands showed asymmetric light curves to be a negative type of the O'Connell effect, which can be described by magnetic activity of a cool spot on the more massive component. Our photometric solutions showed that V873 Per is a W-type with a mass ratio of q=2.504(+/-0.0029), confirming the results of Samec et al. (2009IBVS.5901....1S). The derived contact degree was found to be f=18.10%(+/-1.36%). Moreover, our analysis found the cyclic variation with the period of about 4yr that could be due to existence of the third companion in the system or the mechanism of magnetic activity cycle in the binary. While available data indicated that the long-term orbital period tends to be stable rather than decreasing.
- ID:
- ivo://CDS.VizieR/J/A+A/408/611
- Title:
- V436 Persei UBV photometry
- Short Name:
- J/A+A/408/611
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An analysis of new spectroscopic and photoelectric UBV observations, satisfactorily covering the whole orbital period of V436 Per, together with existing data allowed us to improve the knowledge of the basic physical characteristics of the binary and its components. In several aspects, our new results differ from the findings of Paper I (Harmanec et al., 1997, Cat. <J/A+A/319/867>) of this series: In particular, we found that it is the star eclipsed in the secondary minimum which is slightly more massive and larger than the optical primary. We also conclude that the apsidal advance -- if present at all -- is much slower than that estimated in a previous study. The orbital period might be increasing by 0.28 s per year but also this finding is very uncertain and needs verification by future observations. It is encouraging to note that two completely independent sets of programs for light-curve solutions lead to identical results. A notable finding is that both binary components rotate with very similar -- if not identical -- rotational periods of 1.45d and 1.40d, much shorter than what would correspond to a 10.9d spin-orbit synchronization period at periastron. Rapid line-profile changes reported earlier could not be confirmed from new, dedicated series of high-resolution and S/N spectra.
4557. VPHAS+ DR2 survey
- ID:
- ivo://CDS.VizieR/II/341
- Title:
- VPHAS+ DR2 survey
- Short Name:
- II/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The primary goal of the VST Photometric H{alpha} Survey of the Southern Galactic Plane and Bulge (VPHAS+) is to collect single-epoch ugri broad-band and Ha narrow-band photometry across the southern Galactic Plane within the latitude range -5{deg}<b<+5{deg} down to point source magnitudes of ~21 or better. The VPHAS+ footprint also includes the inner Galactic Bulge, defined as a 20x20 deg^2^ box around the Galactic Centre: this assures optical coverage of the full VVV footprint. For all massive OBA stars this survey is deep enough to explore all but the most heavily obscured locations of the southern Plane, reaching to >4kpc from the Sun. These data will increase the number of known southern emission line stars by up to an order of magnitude, yielding much better statistics on important short-lived types of object. The wide-area uniform photometry obtained will also facilitate stellar population studies, capable of tracing structure over much of the southern Plane. VPHAS+ will trawl the star-formation history of the Galaxy as seen in stellar remnants of all types.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/2036
- Title:
- VPHAS+ survey synthetic colours
- Short Name:
- J/MNRAS/440/2036
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VST Photometric H{alpha} Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and H{alpha} at ~1arcsec angular resolution. Its footprint spans the Galactic latitude range -5{deg}<b<+5{deg} at all longitudes south of the celestial equator. Extensions around the Galactic Centre to Galactic latitudes +/-10{deg} bring in much of the Galactic bulge. This European Southern Observatory public survey, begun on 2011 December 28, reaches down to ~20th magnitude (10{sigma}) and will provide single-epoch digital optical photometry for ~300 million stars. The observing strategy and data pipelining are described, and an appraisal of the segmented narrow-band H{alpha} filter in use is presented. Using model atmospheres and library spectra, we compute main-sequence (u-g), (g-r), (r-i) and (r-H{alpha}) stellar colours in the Vega system. We report on a preliminary validation of the photometry using test data obtained from two pointings overlapping the Sloan Digital Sky Survey. An example of the (u-g, g-r) and (r-H{alpha}, r-i) diagrams for a full VPHAS+ survey field is given. Attention is drawn to the opportunities for studies of compact nebulae and nebular morphologies that arise from the image quality being achieved. The value of the u band as the means to identify planetary-nebula central stars is demonstrated by the discovery of the central star of NGC 2899 in survey data. Thanks to its excellent imaging performance, the VLT Survey Telescope (VST)/OmegaCam combination used by this survey is a perfect vehicle for automated searches for reddened early-type stars, and will allow the discovery and analysis of compact binaries, white dwarfs and transient sources.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A135
- Title:
- V646 Pup TESS and ground photometry and spectrum
- Short Name:
- J/A+A/644/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate small-scale light variations in V646 Pup occurring in the timescales of days, weeks and years. To check if this variability is similar to that observed in FU Ori. We observed V646 Pup on six occasions at the SAAO and CTIO during 2013-2018 in Johnson and Sloan filters, typically with 1 d cadence maintained for 2-4 weeks. We also utilise the public-domain 1512 day long ASAS-SN light curve and TESS photometry obtained in 2019 during 24.1 days with 30 min cadence. New SAAO low-resolution spectra help to update major disc parameters, while the archival high-resolution Keck spectra are used to search for temporal changes in the disc rotational profiles. The ground-based observations confirm the constantly decreasing brightness of V646 Pup at the rate of 0.018mag per year. Precise i-band sensitive TESS data show that the little 0.005-0.01mag light variations imposed on this general trend do consist of a few independent wave trains of apparently time-coherent nature. Assuming that this is typical situation, from analysis of colour-magnitude diagrams obtained on earlier epochs we preliminarily inferred that the bulk of observed light changes could be owing to rotation of disc photosphere inhomogeneities, arising between 10-12 solar radii from the star. It is not excluded that these inhomogeneities could also manifest themselves in rotational profiles of the disc, as obtained from the high-resolution spectra. Assuming Keplerian rotation of these inhomogeneities, we preliminarily determine the stellar mass at 0.7-0.9 solar masses. At least during certain weeks V646 Pup shows time-coherent light variability pattern(s) that could be explained by rotation of an inhomogeneous disc photosphere. These preliminary results are similar to those better established for FU Ori, what suggests a common driving mechanism(s).
- ID:
- ivo://CDS.VizieR/J/AJ/156/220
- Title:
- V, R and I light curves of 4 new low-mass M-type EBs
- Short Name:
- J/AJ/156/220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed multicolor photometric and spectroscopic observations of four new low-mass M-type eclipsing binaries (HAT 225-03429, CRTS J085623.0+282620, CRTS J110302.4+201611, 2MASS J16344899+3716423) in 2017. We obtained new VRI light curves and minimum times of these four systems. Based on our minimum times, we updated the orbital periods and the linear ephemerides using the least squares method. We analyzed these four systems using the Wilson-Devinney program, and obtained the orbital and starspot parameters. The results of our analysis of the light curves indicate that HAT 225-03429 and CRTS J085623.0+282620 are detached eclipsing binaries, CRTS J110302.4+201611 is a semi-detached eclipsing binary, and 2MASS J16344899+3716423 is a contact binary. We performed LAMOST spectroscopic studies of chromospheric activity indicators (H{alpha}, H{beta}, H{gamma}, H{delta}, and Ca II H&K lines) for these four systems for the first time. We first determined their spectral types and calculated the equivalent widths of their chromospheric active indicators. These indicators show that the four low-mass M-type eclipsing binaries are active. Furthermore, the radii of these stars are notably larger than model predictions for their masses, except for the secondary component of HAT 225-03429 and the primary component of CRTS J110302.4+201611.
