Three-dimensional maps of interstellar dust in the Local Arm: using Gaia, 2MASS, and APOGEE-DR14

Abstract

Context. Gaia data and stellar surveys open the way to the construction of detailed 3D maps of the Galactic interstellar (IS) dust based on the synthesis of star distances and extinctions. Dust maps are tools of broad use, including for Gaia-related Milky Way studies. Aims. Reliable extinction measurements require very accurate photometric calibrations. We show the first step of an iterative process linking 3D dust maps and photometric calibrations and improving them simultaneously. Methods. Our previous 3D map of nearby IS dust was used to select low reddening SDSS/APOGEE-DR14 red giants, and this database served for an empirical effective temperature-and metallicity-dependent photometric calibration in the Gaia G and 2MASS K s bands. This calibration has been combined with Gaia G-band empirical extinction coefficients recently published, G, J and K s photometry and APOGEE atmospheric parameters to derive the extinction of a large fraction of the survey targets. Distances were estimated independently using isochrones and the magnitude-independent extinction K J−Ks . This new dataset has been merged with the one used for the earlier version of dust map. A new Bayesian inversion of distance-extinction pairs has been performed to produce an updated 3D map. Results. We present several properties of the new map. Its comparison with 2D dust emission reveals that all large dust shells seen in emission at mid-and high-latitude are closer than 300pc. The updated distribution constrains the well debated, X-ray bright North Polar Spur to originate beyond 800 pc. We use the Orion region to illustrate additional details and distant clouds. On the large scale the map reveals a complex structure of the Local Arm. 2 to 3 kpc-long chains of clouds appear in planes tilted by 15 • with respect to the Galactic plane. A series of cavities oriented along a l 60-240 • axis crosses the Arm. Conclusions. The results illustrate the on-going synergy between 3D mapping of IS dust and stellar calibrations in the context of Gaia. Dust maps provide prior foregrounds for future calibrations appropriate to different target characteristics or ranges of extinction, allowing in turn to increase extinction data and produce more detailed and extended maps.

THOR 42: A touchstone ∼24 Myr-old eclipsing binary spanning the fully-convective boundary

“…This minimal reddening agrees with recent 3D reddening maps (e.g. Lallement et al 2018). We also imposed a prior on the i-band surface brightness ratio, J LCOGT = F 2 /F 1 = 0.520 ± 0.001 which acts as a temperature constraint but is directly related to the observed light curve.…”

Analysing the spectral energy distributions of Galactic classical Cepheids

“…Two 3D reddening models (STILISM, Lallement et al 2018, andfrom Green et al 2019) have been used to compare the values to the adopted reddening values (see the Appendix). There are systematic differences between these two models of order 15%.…”

“…GAIA_SED_LE_fTables_removedCom (2019), Cols. 6-8 are the results from the 3D model by Lallement et al (2018). The E(B − V) value in Col. 6 is the one in the available grid at the distance closest to distance of the object.…”

Modeling the magnetized Local Bubble from dust data

“…Focusing on the overlapping volume to compare with the 3D map of Lallement et al (2018), LE19 showed that their mean reconstruction gives values of the dust density that range from a few orders of magnitude lower to one order of magnitude higher. The latter corresponds to a cloud size that is one order of magnitude smaller, which is expected given that Lallement et al (2018) used a fixed minimum size for their two co-existent kernels. Comparison with the L19 map leads to the same conclusions, which again is expected since, despite the new hierarchical technique, the L19 final step also has a 25 pc resolution limitation.…”