Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/466/L1
- Title:
- VLTI observations of RY Sgr
- Short Name:
- J/A+A/466/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high spatial resolution observations in the mid-infrared of the R CrB star RY Sgr obtained with the Very Large Telescope Interferometer (VLTI) of ESO's Paranal Observatory and MIDI, the MID-infrared Interferometric recombiner. MIDI combines the light of two telescopes and provides spectrally resolved visibilities in the N band atmospheric window. The observations of RY Sgr were conducted with the VLT Unit Telescopes (UTs) UT1, UT3 and UT4, providing projected baselines in the range of 57-129 meters oriented from PA=34{deg} to 135{deg}. The UTs observations were made during the nights of May 25-26th 2005, June 24-25th 2005, June 25-26th 2005 and June 27-28th 2005. All the observations were made under rather good atmospheric conditions. The files include all visibility data recorded from these observations as well as all the characteristics concerning the observations. The log of the observations is shown in Table 1 of the paper (table1.dat).
- ID:
- ivo://CDS.VizieR/J/A+A/546/A24
- Title:
- VLT/NaCo images of HD 142527
- Short Name:
- J/A+A/546/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has long been suggested that circumstellar disks surrounding young stars may be the signposts of planets, and even more so since the recent discoveries of embedded substellar companions. According to models, the planet-disk interaction may create large structures, gaps, rings, or spirals in the disk. In that sense, the Herbig star HD 142527 is particularly compelling, as its massive disk displays intriguing asymmetries that suggest the existence of a dynamical peturber of unknown nature. Our goal was to obtain deep thermal images of the close circumstellar environment of HD 142527 to re-image the reported close-in structures (cavity, spiral arms) of the disk and to search for stellar and substellar companions that could be connected to their presence.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/3131
- Title:
- VMC survey. XXVI. SMC RR Lyrae stars
- Short Name:
- J/MNRAS/473/3131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the analysis of 2997 fundamental mode RR Lyrae variables located in the Small Magellanic Cloud (SMC). For these objects, near-infrared time series photometry from the VISTA survey of the Magellanic Clouds system (VMC) and visual light curves from the OGLE IV (Optical Gravitational Lensing Experiment IV) survey are available. In this study, the multi-epoch Ks-band VMC photometry was used for the first time to derive intensity-averaged magnitudes of the SMC RR Lyrae stars. We determined individual distances to the RR Lyrae stars from the near-infrared period-absolute magnitude-metallicity (PM_Ks_Z) relation, which has some advantages in comparison with the visual absolute magnitude-metallicity (M_V_-[Fe/H]) relation, such as a smaller dependence of the luminosity on interstellar extinction, evolutionary effects and metallicity. The distances we have obtained were used to study the three-dimensional structure of the SMC. The distribution of the SMC RR Lyrae stars is found to be ellipsoidal. The actual line-of-sight depth of the SMC is in the range 1-10kpc, with an average depth of 4.3+/-1.0kpc. We found that RR Lyrae stars in the eastern part of the SMC are affected by interactions of the Magellanic Clouds. However, we do not see a clear bimodality observed for red clump stars, in the distribution of RR Lyrae stars.
- ID:
- ivo://CDS.VizieR/J/A+A/636/A48
- Title:
- VMC Survey. XXXVII. MC AGB stars
- Short Name:
- J/A+A/636/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Variability is a key property of stars on the asymptotic giant branch (AGB). Selection criteria are derived based on colour-colour and colour-magnitude diagrams from the combination of VISTA Magellanic Cloud (VMC) survey, Spitzer IRAC, and AllWISE data. After eliminating LPVs with known periods shorter than 450 days, a sample of 1299 candidate obscured AGB stars is selected. K-band LCs are constructed combining the epoch photometry available in the VMC survey with literature data, analysed for variability and fitted with a single period sine curve to derive mean magnitudes, amplitudes and periods. A subset of 254 stars are either new variables, or known variables where the period we find is better determined than the literature value, or longer than 1000 days. The spectral energy distributions (SEDs) of these stars are fitted to a large number of templates. For this purpose the SEDs and Spitzer IRS spectra of some non-AGB stars (Be stars, Hii regions and young stellar objects [YSOs]) are also fitted to have templates of the most likely contaminants in the sample. A sample of 217 likely LPVs is found. Thirty-four stars have periods longer than 1000 days although some of them have alternative shorter periods.
- ID:
- ivo://CDS.VizieR/J/MNRAS/494/458
- Title:
- VMC XXXVI. Young stellar variability in LMC
- Short Name:
- J/MNRAS/494/458
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of young stellar objects (YSOs) in the Galaxy have found that a significant fraction exhibits photometric variability. However, no systematic investigation has been conducted on the variability of extragalactic YSOs. Here we present the first variability study of massive YSOs in an ~1.5 square degree region of the Large Magellanic Cloud (LMC). The aim is to investigate whether the different environmental conditions in the metal-poor LMC (~0.4-0.5Z_{sun}_) have an impact on the variability characteristics. Multi-epoch near-infrared (NIR) photometry was obtained from the VISTA Survey of the Magellanic Clouds (VMC) and our own monitoring campaign using the VISTA telescope. By applying a reduced {Chi}-square-analysis, stellar variability was identified. We found 3062 candidate variable stars from a population of 362425 stars detected. Based on several Spitzer studies, we compiled a sample of high-reliability massive YSOs: a total of 173 massive YSOs have NIR counterparts (down to Ks~18.5mag) in the VMC catalogue, of which 39 display significant (>3{sigma}) variability. They have been classified as eruptive, fader, dipper, short-term variable, and long-period variable YSOs based mostly on the appearance of their Ks-band light curves. The majority of YSOs are aperiodic; only five YSOs exhibit periodic light curves. The observed amplitudes are comparable or smaller than those for Galactic YSOs (only two Magellanic YSOs exhibit {Delta}Ks>1mag), not what would have been expected from the typically larger mass accretion rates observed in the Magellanic Clouds.
1627. V960 Mon light curves
- ID:
- ivo://CDS.VizieR/J/A+A/582/L12
- Title:
- V960 Mon light curves
- Short Name:
- J/A+A/582/L12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We monitored the recent FUor 2MASS J06593158-0405277 (V960 Mon) since November 2009 at various observatories and multiple wavelengths. After the outburst by nearly 2.9mag in r around September 2014 the brightness gently fades until April 2015 by nearly 1mag in U and 0.5mag in z. Thereafter the brightness at {lambda}>5000{AA} was constant until June 2015 while the shortest wavelengths (U,B) indicate a new rise, similar to that seen for the FUor V2493 Cyg (HBC722). Our near-infrared (NIR) monitoring between December 2014 and April 2015 shows a smaller outburst amplitude (~2mag) and a smaller (0.2-0.3mag) post-outburst brightness decline. Optical and NIR color-magnitude diagrams indicate that the brightness decline is caused by growing extinction. The post-outburst light curves are modulated by an oscillating color-neutral pattern with a period of about 17 days and an amplitude declining from ~0.08mag in October 2014 to ~0.04mag in May 2015. The properties of the oscillating pattern lead us to suggest the presence of a close binary with eccentric orbit.
- ID:
- ivo://CDS.VizieR/J/ApJ/815/4
- Title:
- V899 Mon long-term monitoring
- Short Name:
- J/ApJ/815/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of V899 Mon (a new member in the FUors/EXors family of young low-mass stars undergoing outburst), based on our long-term monitoring of the source starting from 2009 November to 2015 April. Our optical and near-infrared photometric and spectroscopic monitoring recorded the source transitioning from its first outburst to a short-duration quiescence phase (<1yr), and then returning to a second outburst. We report here the evolution of the outflows from the inner region of the disk as the accretion rate evolved in various epochs. Our high-resolution (R~37000) optical spectrum could resolve interesting clumpy structures in the outflow traced by various lines. Change in far-infrared flux was also detected between two outburst epochs. Based on our observations, we constrained various stellar and envelope parameters of V899 Mon, as well as the kinematics of its accretion and outflow. The photometric and spectroscopic properties of this source fall between classical FUors and EXors. Our investigation of V899 Mon hints at instability associated with magnetospheric accretion being the physical cause of the sudden short-duration pause of the outburst in 2011. It is also a good candidate to explain similar short-duration pauses in outbursts of some other FUors/EXors sources.
1629. V694 Mon plate spectra
- ID:
- ivo://CDS.VizieR/J/A+AS/122/43
- Title:
- V694 Mon plate spectra
- Short Name:
- J/A+AS/122/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the photographic spectral observations of MWC560 carried out in the period 1990-1993. The evolution of the spectrum, the changes in the radial velocities of the different line systems, as well as the variations in the equivalent widths of the different Balmer absorption components, are given and briefly discussed. The suggestion that the hot component of MWC560 ejects high-velocity, highly-collimated jets along the line of sight, is in very good agreement with the observations. All the results, including the variations in the shapes, velocities and equivalent widths of the strong-shifted Balmer absorptions, confirm that compact companion in MWC560 ejects matter in two different regimes - discrete and quasi-stationary. It is supposed that the permanent presence of a relatively weak and small-shifted Balmer absorption component in the spectrum, indicates additional persistent, not spherically symmetric matter outflow.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/148
- Title:
- V346 Nor IJHKs photometry & IR spectra
- Short Name:
- J/ApJ/889/148
- Date:
- 17 Jan 2022 11:51:03
- Publisher:
- CDS
- Description:
- FU Orionis-type objects (FUors) are young low-mass stars undergoing powerful accretion outbursts. The increased accretion is often accompanied by collimated jets and energetic, large-scale molecular outflows. The extra heating during the outburst may also induce detectable geometrical, chemical, and mineralogical changes in the circumstellar material, affecting possible planet formation around these objects. V346 Nor is a southern FUor with peculiar spectral characteristics. Decades after the beginning of its outburst, it unexpectedly underwent a fading event around 2010 due to a decrease in the mass accretion rate onto the star by at least two orders of magnitude. Here we present optical and near-infrared photometry and spectroscopy obtained after the minimum. Our light curves show a gradual re-brightening of V346 Nor, with its Ks-band brightness only 1.5mag below the outburst brightness level. Our Very Large Telescope (VLT)/XSHOOTER spectroscopic observations display several strong forbidden emission lines toward the source from various metals and molecular hydrogen, suggesting the launch of a new jet. Our N-band spectrum obtained with VLT/VISIR outlines a deeper silicate absorption feature than before, indicating that the geometry of the circumstellar medium has changed in the post-outburst period compared to peak brightness.
