| 1. |
- Eyer, L., et al.
(author)
-
Gaia Data Release 2 Variable stars in the colour-absolute magnitude diagram
- 2019
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 623
-
Journal article (peer-reviewed)abstract
- Context. The ESA Gaia mission provides a unique time-domain survey for more than 1.6 billion sources with G less than or similar to 21 mag. Aims. We showcase stellar variability in the Galactic colour-absolute magnitude diagram (CaMD). We focus on pulsating, eruptive, and cataclysmic variables, as well as on stars that exhibit variability that is due to rotation and eclipses. Methods. We describe the locations of variable star classes, variable object fractions, and typical variability amplitudes throughout the CaMD and show how variability-related changes in colour and brightness induce "motions". To do this, we use 22 months of calibrated photometric, spectro-photometric, and astrometric Gaia data of stars with a significant parallax. To ensure that a large variety of variable star classes populate the CaMD, we crossmatched Gaia sources with known variable stars. We also used the statistics and variability detection modules of the Gaia variability pipeline. Corrections for interstellar extinction are not implemented in this article. Results. Gaia enables the first investigation of Galactic variable star populations in the CaMD on a similar, if not larger, scale as was previously done in the Magellanic Clouds. Although the observed colours are not corrected for reddening, distinct regions are visible in which variable stars occur. We determine variable star fractions to within the current detection thresholds of Gaia. Finally, we report the most complete description of variability-induced motion within the CaMD to date. Conclusions. Gaia enables novel insights into variability phenomena for an unprecedented number of stars, which will benefit the understanding of stellar astrophysics. The CaMD of Galactic variable stars provides crucial information on physical origins of variability in a way that has previously only been accessible for Galactic star clusters or external galaxies. Future Gaia data releases will enable significant improvements over this preview by providing longer time series, more accurate astrometry, and additional data types (time series BP and RP spectra, RVS spectra, and radial velocities), all for much larger samples of stars.
|
|
| 2. |
- Pasetti, M., et al.
(author)
-
On the Use of Synchronized LoRaWAN for the Coordination of Distributed Energy Resources in Smart Grids
- 2019
-
In: Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9788887237450
-
Conference paper (peer-reviewed)abstract
- The recent advances in Information and Communication Technology (ICT) are laying down the foundations of future energy systems. The growing availability of reliable and cost-effective ICT solutions are indeed offering the opportunity for the implementation of advanced monitoring and control functions over Distributed Energy Resources (DERs), thus fostering the transition towards decentralized and decarbonized energy systems. The integration of ICT in electrical equipment (such as power converters, metering devices, and protections) is essential for the monitoring and the coordinated control of heterogeneous energy resources, particularly in intermittent and distributed scenarios. Nevertheless, the implementation of such control approaches relies, in the end, on the availability of proper communication infrastructures. The adoption of wired infrastructures (such as field-bus, ethernet, or fiber optic systems) may however imply high installation costs, particularly for complex end-users' systems. To cope with this issue, in this study the use of a wireless network based on the LoRaWAntechnology is proposed to implement the monitoring and the coordinated control of dispersed DERs. A proper communication architecture is proposed and discussed in terms of the required coverage range and latency. Finally, a scalability analysis is also presented, which aims at evaluating the number of devices that can be supervised by a single LoRaWAngateway, by considering the expected data throughput, and the duty cycle limitations. © 2019 AEIT.
|
|
