Mostrar registro simples

dc.contributor.authorSimon, Josh D.pt_BR
dc.contributor.authorSantiago, Basilio Xavierpt_BR
dc.contributor.authorDES Collaborationpt_BR
dc.date.accessioned2020-08-04T03:39:10Zpt_BR
dc.date.issued2020pt_BR
dc.identifier.issn0004-637Xpt_BR
dc.identifier.urihttp://hdl.handle.net/10183/212589pt_BR
dc.description.abstractWe present Magellan/IMACS spectroscopy of three recently discovered ultra-faint Milky Way satellites, Grus II, Tucana IV, and Tucana V. We measure systemic velocities of vhel =-  110.0 0.5 - km s 1 , = - + vhel 15.9 1.7 1.8 - km s 1, and = - - + vhel 36.2 2.2 2.5 - km s 1 for the three objects, respectively. Their large relative velocities demonstrate that the satellites are unrelated despite their close physical proximity. We determine a velocity dispersion for Tuc IV of s = - + 4.3 1.0 1.7 - km s 1 , but we cannot resolve the velocity dispersions of the other two systems. For Gru II, we place an upper limit (90% confidence) on the dispersion of σ < 1.9 - km s 1, and for Tuc V, we do not obtain any useful limits. All three satellites have metallicities below [Fe H 2.1 ] = - , but none has a detectable metallicity spread. We determine proper motions for each satellite based on Gaia astrometry and compute their orbits around the Milky Way. Gru II is on a tightly bound orbit with a pericenter of - + 25 7 6 kpc and orbital eccentricity of - + 0.45 0.05 0.08. Tuc V likely has an apocenter beyond 100 kpc and could be approaching the Milky Way for the first time. The current orbit of Tuc IV is similar to that of Gru II, with a pericenter of - + 25 8 11 kpc and an eccentricity of - + 0.36 0.06 0.13. However, a backward integration of the position of Tuc IV demonstrates that it collided with the Large Magellanic Cloud at an impact parameter of 4 kpc ∼120 Myr ago, deflecting its trajectory and possibly altering its internal kinematics. Based on their sizes, masses, and metallicities, we classify Gru II and Tuc IV as likely dwarf galaxies, but the nature of Tuc V remains uncertain.en
dc.format.mimetypeapplication/pdfpt_BR
dc.language.isoengpt_BR
dc.relation.ispartofThe astrophysical journal. Bristol. Vol. 892, no. 2 (Apr. 2020), 137, 16 p.pt_BR
dc.rightsOpen Accessen
dc.subjectLocal groupen
dc.subjectGaláxias anãspt_BR
dc.subjectDwarf galaxiesen
dc.subjectNuvens de magalhaespt_BR
dc.subjectVia lácteapt_BR
dc.subjectMagellanic cloudsen
dc.subjectMilky way galaxyen
dc.subjectMatéria escurapt_BR
dc.subjectDark matteren
dc.titleBirds of a Feather? : Magellan/IMACS spectroscopy of the ultra-faint satellites Grus II, Tucana IV, and Tucana Vpt_BR
dc.typeArtigo de periódicopt_BR
dc.identifier.nrb001115270pt_BR
dc.type.originEstrangeiropt_BR


Thumbnail
   

Este item está licenciado na Creative Commons License

Mostrar registro simples