We analyze the role of first (leading) author gender on the number ofcitations that a paper receives, on the publishing frequency and on theself-citing tendency. We consider a complete sample of over 200,000publications from 1950 to 2015 from five major astronomy journals. We determinethe gender of the first author for over 70% of all publications. The fractionof papers which have a female first author has increased from less than 5% inthe 1960s to about 25% today. We find that the increase of the fraction ofpapers authored by females is slowest in the most prestigious journals such asScience and Nature. Furthermore, female authors write 19$\pm$7% fewer papers inseven years following their first paper than their male colleagues. At alltimes papers with male first authors receive more citations than papers withfemale first authors. This difference has been decreasing with time and amountsto $\sim$6% measured over the last 30 years. To account for the fact that theproperties of female and male first author papers differ intrinsically, we usea random forest algorithm to control for the non-gender specific properties ofthese papers which include seniority of the first author, number of references,total number of authors, year of publication, publication journal, field ofstudy and region of the first author's institution. We show that papersauthored by females receive 10.4$\pm$0.9% fewer citations than what would beexpected if the papers with the same non-gender specific properties werewritten by the male authors. Finally, we also find that female authors in oursample tend to self-cite more, but that this effect disappears when controlledfor non-gender specific variables.

We present Keck/DEIMOS spectroscopy of individual stars in the relativelyisolated Local Group dwarf galaxies Leo A, Aquarius, and the Sagittarius dwarfirregular galaxy. The three galaxies--but especially Leo A and Aquarius--sharein common delayed star formation histories relative to many other isolateddwarf galaxies. The stars in all three galaxies are supported by dispersion. Wefound no evidence of stellar velocity structure, even for Aquarius, which hasrotating HI gas. The velocity dispersions indicate that all three galaxies aredark matter-dominated, with dark-to-baryonic mass ratios ranging from$4.4^{+1.1}_{-0.8}$ (SagDIG) to $9.6^{+2.5}_{-1.8}$ (Aquarius). Leo A andSagDIG have lower stellar metallicities than Aquarius, and they also havehigher gas fractions, both of which would be expected if Aquarius were fartheralong in its chemical evolution. The metallicity distribution of Leo A isinconsistent with a Closed or Leaky Box model of chemical evolution, suggestingthat the galaxy was pre-enriched or acquired external gas during starformation. The metallicities of stars increased steadily for all threegalaxies, but possibly at different rates. The [$\alpha$/Fe] ratios at a given[Fe/H] are lower than that of the Sculptor dwarf spheroidal galaxy, whichindicates more extended star formation histories than Sculptor, consistent withphotometrically derived star formation histories. Overall, the bulk kinematicand chemical properties for the late-forming dwarf galaxies do not divergesignificantly from those of less delayed dwarf galaxies, including dwarfspheroidal galaxies.

We identify six ultra diffuse galaxies (UDGs) outside clusters in threenearby isolated groups (z<0.026) using very deep imaging in three differentSDSS filters (g, r and i bands) from the IAC Stripe82 Legacy Project. Bycomparing with the abundance of UDGs in rich galaxy clusters, we find that thedensity of UDGs (i.e. their number per unit mass of the host structure wherethey are located) decreases towards the most massive systems. This iscompatible with a scenario where UDGs are formed preferentially outsideclusters. In the periphery (D>250 kpc) of our three groups, we identify apopulation of potential UDG progenitors (two of them confirmedspectroscopically). These progenitors have similar masses, shapes and sizes butare bluer, g-i~0.45, (and for this reason brighter, mu_g(0)<24 mag arcsec -2)than traditional UDGs (g-i~0.76). A passive evolution of these progenitors willtransform them into regular (i.e. mu_g(0)>24 mag arcsec -2) UDGs after ~6 Gyr.If confirmed, our observations support a scenario where UDGs are old, extended,low surface brightness dwarfs (M*~10^8 Msun) galaxies born in the field, arelater on processed in groups and, ultimately, infall into galaxy clusters bygroup accretion.