- 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.
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23932. V396 Mon BVRI light curves
- ID:
- ivo://CDS.VizieR/J/AJ/141/44
- Title:
- V396 Mon BVRI light curves
- Short Name:
- J/AJ/141/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper analyzes the first obtained four-color light curves of V396 Mon using the 2003 version of the W-D code. It is confirmed that V396 Mon is a shallow W-type contact binary system with a mass ratio q=2.554(+/-0.004) and a degree of contact factor f=18.9%(+/-1.2%). A period investigation based on all available data shows that the period of the system includes a long-term decrease (dP/dt=-8.57x10^-8^days/yr) and an oscillation (A3=0.0160day, T3=42.4yr). They are caused by angular momentum loss and light-time effect, respectively. The suspect third body is possibly a small M-type star (about 0.31 solar mass).
23933. 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.
23935. 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.
23936. V838 Mon spectrum in 2009
- ID:
- ivo://CDS.VizieR/J/A+A/532/A138
- Title:
- V838 Mon spectrum in 2009
- Short Name:
- J/A+A/532/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V838 Mon erupted at the beginning of 2002. In the course of the outburst the object evolved to low effective temperatures and declined as a very late M-type supergiant. Among various scenarios proposed to explain the nature of the outburst, the most promising is a stellar merger event. We aim at studying the structure and evolution of the object in the decline from the 2002 eruption. We obtained spectroscopic observations of V838 Mon in January-March 2009 with UVES/VLT. The results are analysed and compared with similar observations obtained in October 2005 with HIRES/Keck. The most striking difference between 2009 and 2005 is a complete absence of the B3 V component and of the [FeII] emission lines in 2009. The present spectrum displays only the spectrum of the 2002 eruption remnant. It resembles that of an ~M6 giant, although the molecular bands in V838 Mon are deeper than those in standard stellar spectra of a similar spectral class. Several atomic lines, which displayed P-Cyg profiles in 2005, are now dominated by pure absorptions. Some of these lines, however, show a narrow emission component, which, as we argue, measures the radial velocity of V838 Mon. The resulting heliocentric velocity is 71km/s, which very well agrees with the velocity obtained from SiO maser observations. The atomic lines and the molecular bands show very complex kinematics. In some atomic lines and high-excitation molecular bands we observe matter infalling in the object atmosphere. The infall components were already observed in 2005, but were less pronounced and present in fewer lines than in 2009. We argue that the most negative radial velocity components seen in the resonance atomic lines and in the low-excitation molecular bands were formed in the ejecta of the 2002 eruption. The B3V companion most probably became engulfed in an opaque dusty matter of the 2002 V838 Mon ejecta.
- 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.
23938. Vocabularies in the VO
- ID:
- ivo://ivoa.net/std/vocabularies
- Title:
- Vocabularies in the VO
- Short Name:
- vocabularies
- Date:
- 02 Jun 2023 00:30:00
- Publisher:
- IVOA
- Description:
- In this document, we discuss practices related to the use of RDF-based consensus vocabularies in the Virtual Observatory, that is the creation, publication, maintenance, and consumption of hierarchical word lists agreed upon within the IVOA. To cover the wide range of use cases envisoned, we define different vocabulary types for informal knowledge organisation on the one hand, and strict hierarchies of classes and properties on the other. While the framework rests on the solid foundations of W3C RDF, provisions are made to facilitate using IVOA vocabularies without specific RDF tooling. Non-normative appendices detail the current vocabulary-related tooling.
- ID:
- ivo://ivoa.net/std/VODML
- Title:
- VO-DML: a consistent modeling language for IVOA data models
- Date:
- 31 May 2018 09:00:00
- Publisher:
- IVOA
- Description:
- This document defines a standard modelling language, or meta-model, for expressing data models in the IVOA. Adopting such a uniform language for all models allows these to be used in a homogeneous manner and allows a consistent definition of reuse of one model by another. The particular language defined here includes a consistent identification mechanism for model which allows these to be referenced in an explicit and uniform manner also from other contexts, in particular from othe IVOA standard formats such as VOTable. The language defined in this specification is named VO-DML (VO Data Modeling Language). VO-DML is a conceptual modeling language that is agnostic of serializations, or physical representations. This allows it to be designed to fit as many purposes as possible. VO-DML is directly based on UML, and can be seen as a particular representation of a UML2 Profile. VO-DML is restricted to describing static data structures and from UML it only uses a subset of the elements defined in its language for describing "Class Diagrams". Its concepts can be easily mapped to equivalent data modelling concepts in other representations such as relational databases, XML schemas and object-oriented computer languages. VO-DML has a representation as a simple XML dialect named VO-DML/XML that must be used to provide the formal representation of a VO-MDL data model. VO-DML/XML aims to be concise, explicit and easy to parse and use in code that needs to interpret annotated data sets. VO-DML as described in this document is an example of a domain specific modeling language, where the domain here is defined as the set of data and meta-data structures handled in the IVOA and Astronomy at large. VO-DML provides a custom representation of such a language and as a side effect allows the creation and use of standards compliant data models outside of the IVOA standards context.
- ID:
- ivo://padc.obspm.planeto/meteor_showers/q/epn_core
- Title:
- VOEvent meteor shower service
- Short Name:
- Meteor Showers
- Date:
- 16 Jul 2024 13:55:03
- Publisher:
- Paris Astronomical Data Centre
- Description:
- The ephemeris were produced by simulating the ejection of meteoroids from the sunlit hemisphere of cometary nuclei, typically from 0 to 3 au, followed by the propagation of orbits of meteoroids in the Solar System, taking into account the gravity of the Sun, the 8 planets, Pluto, and the Moon, as well as the radiation pressure and the Poynting-Robertson drag. Note that asteroid parent bodies were considered as active (i.e. comet-like bodies) even if they are not active today. The showers are predicted when a planet enters a large enough set of meteoroids, at a distance less than typically 0.01 au. See Vaubaillon J., Colas F., Jorda L. 2005 A new method to predict meteor showers. I. Description of the model, Astronomy and Astrophysics, Volume 439/2 p.751-760, as well as: Vaubaillon J. 2017 A confidence index for forecasting of meteor showers, Planetary and Space Science, Volume 143 p.78-82
