| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Antoja, T., et al.
(author)
-
Asymmetric metallicity patterns in the stellar velocity space with RAVE
- 2017
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 601
-
Journal article (peer-reviewed)abstract
- Context. The chemical abundances of stars encode information on their place and time of origin. Stars formed together in e.g. a cluster, should present chemical homogeneity. Also disk stars influenced by the effects of the bar and the spiral arms might have distinct chemical signatures depending on the type of orbit that they follow, e.g. from the inner versus outer regions of the Milky Way.Aims. We explore the correlations between velocity and metallicity and the possible distinct chemical signatures of the velocity over-densities of the local Galactic neighbourhood.Methods. We use the large spectroscopic survey RAVE and the Geneva Copenhagen Survey. We compare the metallicity distribution of regions in the velocity plane (upsilon(R), upsilon(phi)) with that of their symmetric counterparts (-upsilon(R), upsilon(phi)). We expect similar metallicity distributions if there are no tracers of a sub-population (e.g. a dispersed cluster, accreted stars), if the disk of the Galaxy is axisymmetric, and if the orbital effects of the bar and the spiral arms are weak.Results. We find that the metallicity-velocity space of the solar neighbourhood is highly patterned. A large fraction of the velocity plane shows differences in the metallicity distribution when comparing symmetric upsilon(R) regions. The typical differences in the median metallicity are of 0 : 05 dex with statistical significant of at least 95% confidence, and with values up to 0 : 6 dex. For stars with low azimuthal velocity v(phi), the ones moving outwards. These include stars in the Hercules and Hyades moving groups and other velocity branch-like structures. For higher v(phi), the stars moving inwards have higher metallicity than those moving outwards. We have also discovered a positive gradient in v(phi) with resp ect to metallicity at high metallicities, apart from the two known positive and negative gradients for the thick and thin disks.Conclusions. The most likely interpretation of the metallicity asymmetry is that it is mainly due to the orbital effects of the Galactic bar and the radial metallicity gradient of the disk. We present a simulation that supports this idea.
|
|
| 5. |
- Kordopatis, G., et al.
(author)
-
In the thick of it: metal-poor disc stars in RAVE
- 2013
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 1365-2966 .- 0035-8711. ; 436, s. 3231-3246
-
Journal article (peer-reviewed)
|
|
| 6. |
|
|
| 7. |
- Kunder, Andrea, et al.
(author)
-
THE RADIAL VELOCITY EXPERIMENT (RAVE) : FIFTH DATA RELEASE
- 2017
-
In: The Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 153:2
-
Journal article (peer-reviewed)abstract
- Data Release 5 (DR5) of the Radial Velocity Experiment (RAVE) is the fifth data release from a magnitude-limited (9 < I < 12) survey of stars randomly selected in the Southern Hemisphere. The RAVE medium-resolution spectra (R ∼ 7500) covering the Ca-triplet region (8410-8795 A) span the complete time frame from the start of RAVE observations in 2003 to their completion in 2013. Radial velocities from 520,781 spectra of 457,588 unique stars are presented, of which 255,922 stellar observations have parallaxes and proper motions from the Tycho-Gaia astrometric solution in Gaia DR1. For our main DR5 catalog, stellar parameters (effective temperature, surface gravity, and overall metallicity) are computed using the RAVE DR4 stellar pipeline, but calibrated using recent K2 Campaign 1 seismic gravities and Gaia benchmark stars, as well as results obtained from high-resolution studies. Also included are temperatures from the Infrared Flux Method, and we provide a catalog of red giant stars in the dereddened color - (J Ks) 0 interval (0.50, 0.85) for which the gravities were calibrated based only on seismology. Further data products for subsamples of the RAVE stars include individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni, and distances found using isochrones. Each RAVE spectrum is complemented by an error spectrum, which has been used to determine uncertainties on the parameters. The data can be accessed via the RAVE Web site or the VizieR database.
|
|
| 8. |
- Reinhold, Ingo, 1981-, et al.
(author)
-
A hybrid approach combining 3D and conductive inkjet printing for the generation of linear ion traps for mass spectrometry applications
- 2014
-
In: International Conference on Digital Printing Technologies. - : Society for Imaging Science and Technology. ; , s. 133-136, s. 133-136
-
Conference paper (peer-reviewed)abstract
- Printed conductors have attracted strong interest in academia as well as the industry. While first applications using printed conductors on flat as well as curved surfaces are establishing in the market, extensive research still is conducted on the postprocessing technologies needed for high-volume fabrication of solution processed conductors. With regards to the potential low-cost, high-throughput manufacturing of conductors on inexpensive polymeric foils, new applications start to evolve that call for an even more elaborate investigation of the printing and post-processing steps included. This paper assesses the potential of inkjet-printed conductors for the use in low-pressure environments, such as linear ion-traps for mass spectrometry. In these environments remainders of trapped air or organic solvents affect the performance and lifetime of the getter pump systems used. Additionally, high frequency characteristics of the processed conductors are investigated as these are essential for the sensitivity of an ion trap. In this contribution we establish the framework for the application of conductive Inkjet printing on curved surfaces for sensing application in low-pressure environments. Inkjet-deposited nanoparticle inks were investigated with respect to their characteristics under vacuum conditions. The deposits on polymeric foils as well as on DLP processed three-dimensional semi-finished parts were subjected to thermal post-processing and measured with respect to their electrical characteristics as well as their outgassing behavior.
|
|
| 9. |
|
|
| 10. |
|
|
