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SkyMapper Southern Survey: Second data release (DR2)
Wolf, Christian; Schmidt, Brian P.; Onken, Christopher A. +6 more
We present the second data release (DR2) of the SkyMapper Southern Survey, a hemispheric survey carried out with the SkyMapper Telescope at Siding Spring Observatory in Australia, using six optical filters: u, v, g, r, i, z. DR2 is the first release to go beyond the ∼18 mag (10σ) limit of the Shallow Survey released in the first data release (DR1)…
Stellar accelerations and the galactic gravitational field
Easther, Richard; Silverwood, Hamish
Typical stars in the Milky Way galaxy have velocities of hundreds of kilometres per second and experience gravitational accelerations of ∼10-10 m s-2, resulting in velocity changes of a few centimetres per second over a decade. Measurements of these accelerations would permit direct tests of the applicability of Newtonian dyn…
Galactic calibration of the tip of the red giant branch
Clementini, Gisella; Da Costa, Gary; Mould, Jeremy
Indications from Gaia data release 2 are that the tip of the red giant branch (a population II standard candle related to the helium flash in low mass stars) is close to -4 in absolute I magnitude in the Cousins photometric system. Our sample is high-latitude southern stars from the thick disk and inner halo, and our result is consistent with long…
Two's company, three's a crowd: SALT reveals the likely triple nature of the nucleus of the extreme abundance discrepancy factor planetary nebula Sp 3
Miszalski, Brent; Manick, Rajeev; Rauch, Thomas +3 more
The substantial number of binary central stars of planetary nebulae (CSPNe) now known (∼50) has revealed a strong connection between binarity and some morphological features including jets and low-ionisation structures. However, some morphological features and asymmetries might be too complex or subtle to ascribe to binary interactions alone. In t…
Analysis of the disc components of our galaxy via kinematic and spectroscopic procedures
Bilir, S.; Karaali, S.; Plevne, O. +1 more
We used the spectroscopic and astrometric data provided from the GALactic Archaeology with HERMES (GALAH) Data Release (DR2) and Gaia DR2, respectively, for a large sample of stars to investigate the behaviour of the [α/Fe] abundances via two procedures, that is, kinematically and spectroscopically. With the kinematical procedure, we investigated …
Difference of source regions between fast and slow coronal mass ejections
Filippov, B.
Coronal mass ejections (CMEs) are tightly related to filament eruptions and usually are their continuation in the upper solar corona. It is common practice to divide all observed CMEs into fast and slow ones. Fast CMEs usually follow eruptive events in active regions near big sunspot groups and associated with major solar flares. Slow CMEs are mor…