Zhu, LingLingZhuvan de Ven, GlennGlennvan de Venvan den Bosch, RemcoRemcovan den BoschRix, Hans-WalterHans-WalterRixLyubenova, MariyaMariyaLyubenovaFalcón-Barroso, JesúsJesúsFalcón-BarrosoMartig, MarieMarieMartigMao, ShudeShudeMaoXu, DandanDandanXuJin, YunpengYunpengJinObreja, AuraAuraObrejaGrand, Robert J. J.Robert J. J.GrandDutton, Aaron A.Aaron A.DuttonMacciò, Andrea V.Andrea V.MacciòGómez, Facundo A.Facundo A.GómezWalcher, Jakob C.Jakob C.WalcherGarcía-Benito, RubénRubénGarcía-BenitoZIBETTI, StefanoStefanoZIBETTISánchez, Sebastian F.Sebastian F.Sánchez2020-10-232020-10-2320182397-3366http://hdl.handle.net/20.500.12386/27952Galaxy formation entails the hierarchical assembly of mass, along with the condensation of baryons and the ensuing, self-regulating star formation<SUP>1,2</SUP>. The stars form a collisionless system whose orbit distribution retains dynamical memory that can constrain a galaxy's formation history<SUP>3</SUP>. The orbits dominated by ordered rotation, with near-maximum circularity λ<SUB>z</SUB> ≈ 1, are called kinematically cold, and the orbits dominated by random motion, with low circularity λ<SUB>z</SUB> ≈ 0, are kinematically hot. The fraction of stars on `cold' orbits, compared with the fraction on `hot' orbits, speaks directly to the quiescence or violence of the galaxies' formation histories<SUP>4,5</SUP>. Here we present such orbit distributions, derived from stellar kinematic maps through orbit-based modelling for a well-defined, large sample of 300 nearby galaxies. The sample, drawn from the CALIFA survey<SUP>6</SUP>, includes the main morphological galaxy types and spans a total stellar mass range from 10<SUP>8.7</SUP> to 10<SUP>11.9</SUP> solar masses. Our analysis derives the orbit-circularity distribution as a function of galaxy mass and its volume-averaged total distribution. We find that across most of the considered mass range and across morphological types, there are more stars on `warm' orbits defined as 0.25 ≤ λ<SUB>z</SUB> ≤ 0.8 than on either `cold' or `hot' orbits. This orbit-based `Hubble diagram' provides a benchmark for galaxy formation simulations in a cosmological context.STAMPAenArticle10.1038/s41550-017-0348-12-s2.0-85042698787000429087000020https://www.nature.com/articles/s41550-017-0348-12018NatAs...2..233ZFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_8 Formation and evolution of galaxies