We present new empirical estimates of the ΔV bump HB parameter for 15 Galactic globular clusters (GGCs) using accurate and homogeneous ground-based optical data...
Open Cluster Chemical Homogeneity throughout the Milky Way
The chemical homogeneity of surviving stellar clusters contains important clues about interstellar medium (ISM) mixing efficiency, star formation, and the...
Optical and Infrared Observations of the Bipolar Proto-Planetary Nebula Henize 401
Based on optical and near-infrared ground-based spectroscopy and optical and near-infrared Hubble Space Telescope (HST) images, we confirm the classification of...
Optical and Near-infrared Spectra of σ Orionis Isolated Planetary-mass Objects
We have obtained low-resolution optical (0.7–0.98 μm) and near-infrared (1.11–1.34 μm and 0.8–2.5 μm) spectra of 12 isolated planetary-mass candidates (J = 18.2...
Optical Counterparts of Ultraluminous X-Ray Sources
We present the optical identification and characterization of counterparts of four objects previously cataloged as ultraluminous X-ray (ULX) sources. The...
Optical Emission of the Ultraluminous X-Ray Source NGC 5408 X-1: Donor Star or Irradiated Accretion Disk?
We obtained three epochs of simultaneous Hubble Space Telescope (HST)/Wide Field Camera 3 and Chandra observations of the ultraluminous X-ray source (ULX) NGC...
Optical Linear Polarization of Late M and L Type Dwarfs
We report on the linear polarimetric observations in the Johnson I-band filter of 44 ultracool dwarfs with spectral types between M6 and L7.5, corresponding to...
Optical Microvariability in Quasars: Spectral Variability
We present a method that we developed to discern where the optical microvariability (OM) in quasars originates: in the accretion disk (related to thermal...
Optical Observations of Psr J2021+3651 in the Dragonfly Nebula With the GTC
PSR J2021+3651 is a 17 kyr old rotation powered pulsar detected in the radio, X-rays, and γ-rays. It powers a torus-like pulsar wind nebula with jets, dubbed...