SkyMapper stellar parameters for Galactic Archaeology on a grand-scale

Abstract

The SkyMapper photometric surveys provides uvgriz photometry for several millions sources in the Southern sky. We use DR1.1 to explore the quality of its photometry, and develop a formalism to homogenise zero-points across the sky using stellar effective temperatures. Physical flux transformations, and zero-points appropriate for this release are derived, along with relations linking colour indices to stellar parameters. Reddening-free pseudo-colours and pseudo-magnitudes are also introduced. For late-type stars which are best suited for Galactic Archaeology, we show that SkyMapper+2MASS are able to deliver a precision better than 100 K in effective temperatures (depending on the filters), ∼ 0.2 dex for metallicities above −2, and a reliable distinction between M-dwarfs and -giants. Together with astrometric and asteroseismic space mission, SkyMapper promises to be a treasure trove for stellar and Galactic studies.

Characteristics of the Two Sequences Seen in the High-velocity Hertzsprung–Russell Diagram in Gaia DR2*

“…With GALAH DR3 on the horizon the SkyMapper team is set to update their calibration; however, we do not need to wait for this to undertake the current investigation, as by looking at the Gaia colors and magnitudes and using the knowledge about metallicities from the RGB as a prior to our investigation, we can circumnavigate this particular problem. The SkyMapper magnitudes have been corrected for reddening using rescaled E(B − V ) from the Schlegel et al (1998) map as described by Casagrande et al (2019). We use these same E(B − V ) estimates, combined with the mean extinction coefficients given by Casagrande & VandenBerg (2018, Table 2), to correct the Gaia magnitudes for reddening.…”

The Pristine survey – VI. The first three years of medium-resolution follow-up spectroscopy of Pristine EMP star candidates

“…Caffau et al 2013;Aoki et al 2013;Allende Prieto et al 2015;Aguado et al 2016;Li et al 2015;Aguado et al 2017aAguado et al ,b, 2018a, mostly with the help of large spectroscopic surveys such as the Sloan Digital Sky Survey (SDSS, York et al 2000), the Sloan Extension for Galactic Understanding and Exploration (SEGUE, Yanny et al 2009), the Baryonic Oscillations Spectroscopic Survey (BOSS, Eisenstein et al 2011;Dawson et al 2013), and more recently the large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, Deng et al 2012). More targeted searches have also been in use for many years, from early efforts using a Ca H & K objective-prism technique, such as the HK survey (Beers et al 1985(Beers et al , 1992 and the Hamburg ESO survey (Christlieb et al 2002), to more recent efforts using targeted narow/medium-band photometry at blue wavelengths, like the SkyMapper survey (Keller et al 2007;Wolf et al 2018;Casagrande et al 2019;Huang et al 2019), and the Pristine survey (Starkenburg et al 2017b).…”

The K2 Galactic Caps Project – going beyond the Kepler field and ageing the Galactic disc

“…shows. This is potentially true, but the photometric distribution has greater scatter compared to the RAVE and APOGEE survey metallicities (see Casagrande et al 2019). This is demonstrated by the extension to unlikely metallicities of > 0.5 dex for K2 SM.…”

“…To supplement this information, photometric values of T eff and [Fe/H] determined from observations by the SkyMapper survey (Keller et al 2007;Wolf et al 2018) have been used. SkyMapper is designed to take uvgriz photometry, from which stellar parameters can be derived (Casagrande et al 2019). The reported survey parameters have been calibrated using GALAH (Buder et al 2018) spectroscopic metallicities and T eff from the InfraRed Flux Method, and validated against APOGEE DR14 (Abolfathi et al 2018) and RAVE DR5 to ensure reliable parameter determinations.…”