Counter-dispersed slitless-spectroscopy technique: planetary nebula velocities in the halo of NGC 1399 - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: Using a counter-dispersed slitless spectroscopy technique, we detect andmeasure the line-of-sight velocities of 187 planetary nebulae PNe around oneof the nearest cD galaxies, NGC 1399, with FORS1 on the VLT. We describe themethod for identifying and classifying the emission-line sources and theprocedure for computing their J2000 coordinates and velocities. The number ofPN detections and the errors in the velocity measurements 37 km-s indicatethat this technique is comparable to other methods, such as that described byTeodorescu et al. 2005. We present the spatial distribution of the PNe and abasic analysis of their velocities. The PN two-dimensional velocity field showsmarginal rotation consistent with other studies. We also find a low-velocitysubstructure in the halo and a flatter velocity-dispersion profile compared toprevious observations that extends to ~400 arcsec. The detection of alow-velocity subcomponent underscores the importance of discrete velocitytracers for the detection of un-mixed components. The new velocity-dispersionprofile is in good agreement with revised velocity dispersions for the redglobular clusters in NGC 1399, using the data of Schuberth et al. 2009. Theouter parts of this profile are consistent with one of the dynamical models ofKronawitter et al. 2000, which corresponds to a circular velocity of ~340km-s and a rescaled B-band mass-to-light ratio of ~20 at 7- radius. Thesemeasurements trace the kinematics of the outer halo and disentangle theheterogenous populations in the Fornax Cluster core. The new data set the stagefor a revised dynamical model of the outer halo of NGC 1399.



Autor: Emily McNeil, Magda Arnaboldi, Ken Freeman, Ortwin Gerhard, Lodovico Coccato, Payel Das

Fuente: https://arxiv.org/







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