English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present the physical characterization of FSR 1758, a new large, massiveobject very recently discovered in the Galactic Bulge. The combination ofoptical data from the 2nd Gaia Data Release (GDR2) and the DECam Plane Survey(DECaPS), and near-IR data from the VISTA Variables in the V\'{\i}a L\'acteaExtended Survey (VVVX) led to a clean sample of likely members. Based on thisintegrated dataset, position, distance, reddening, size, metallicity, absolutemagnitude, and proper motion of this object are measured. We estimate thefollowing parameters: $\alpha=17:31:12$, $\delta=-39:48:30$ (J2000), $D=11.5\pm 1.0$ kpc, $E(J-Ks)=0.20 \pm 0.03$ mag, $R_c=10$ pc, $R_t=150$ pc,$[Fe/H]=-1.5 \pm 0.3$ dex, $M_i < -8.6 \pm 1.0$, $\mu_{\alpha} = -2.85$ masyr$^{-1}$, and $\mu_{\delta} = 2.55$ mas yr$^{-1}$. The nature of this objectis discussed. If FRS 1758 is a genuine globular cluster, it is one of thelargest in the Milky Way, with a size comparable or even larger than that of$\omega$ Cen, being also an extreme outlier in the size vs. Galactocentricdistance diagram. The presence of a concentration of long-period RR Lyraevariable stars and blue horizontal branch stars suggests that it is a typicalmetal-poor globular cluster of Oosterhoff type II. Further exploration of alarger surrounding field reveals common proper motion stars, suggesting eithertidal debris or that FRS\,1758 is actually the central part of a largerextended structure such as a new dwarf galaxy, tentatively named as Scorpius.In either case, this object is remarkable, and its discovery graphicallyillustrates the possibility to find other large objects hidden in the GalacticBulge using future surveys.

A Sequoia in the Garden: FSR 1758 - Dwarf Galaxy or Giant Globular Cluster?