Search Publications
Panchromatic calibration of Ca II triplet luminosity dependence
Dias, B.; Parisi, M. C.
Context. The line strength of the near-infrared Ca II triplet (CaT) lines are a proxy for measuring metallicity from integrated and individual stellar spectra of bright red giant stars. In the latter case it is a mandatory step to remove the magnitude (proxy for gravity, temperature, and luminosity) dependence from the equivalent width (EW) of the…
Did Martian valley networks substantially modify the landscape?
Grau Galofre, Anna; Jellinek, A. Mark; Bahia, Rickbir Singh +2 more
Valley networks are ancient drainage systems incised on the southern hemisphere of Mars, and stand as evidence that liquid water once sculpted its surface. The duration of valley network activity and the sources of water are key questions in deciphering the timing of water stability on early Mars, but remain poorly constrained. In this study we ad…
A search for young exoplanets in Sectors 1-5 of the TESS full-frame images
Armstrong, David J.; Pollacco, Don; Battley, Matthew P.
Young (<1 Gyr) exoplanets represent a critically important area of exoplanet research, as they offer the opportunity to learn about the formation and early dynamic history of exoplanetary systems. However, finding young exoplanets is significantly complicated by the fast rotation and complex activity of their young host stars, which are often n…
Optical spectra of FO Aquarii during low and high accretion rates
Garnavich, P. M.; Marsh, T. R.; Breton, R. P. +7 more
Between 2016 May and 2018 September, the intermediate polar (IP) FO Aquarii exhibited two distinct low states and one failed low state. We present optical spectroscopy of FO Aquarii throughout this period, making this the first detailed study of an accretion disc during a low state in any IP. Analysis of these data confirm that the low states are …
High-resolution spectroscopy of red giants and 'yellow stragglers' in the southern open cluster NGC 2539
Pereira, C. B.; Holanda, N.; Drake, N. A. +1 more
We present a detailed high-resolution spectroscopic analysis of 12 red giant stars, in single and binaries or multiples systems, classified as members of the intermediate-age (631 Myr) open cluster NGC 2539. We used FEROS echelle spectra and the standard LTE analysis to derive the atmospheric parameters for the stars and the abundance ratios of li…
Towards studying hierarchical assembly in real time: a Milky Way progenitor galaxy at z = 2.36 under the microscope
Johnson, Benjamin D.; Bouwens, Rychard; Weisz, Daniel R. +4 more
We use Hubble Space Telescope (HST) imaging and near-infrared spectroscopy from Keck/Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) to study the substructure around the progenitor of a Milky Way-mass galaxy in the Hubble Frontier Fields (HFF). Specifically, we study an $r_\mathrm{ e} = 40^{+70}_{-30}$ pc, $M_{\star } \sim 10^{8.2} \…
Multiepoch VLBI of L Dwarf Binary 2MASS J0746+2000AB: Precise Mass Measurements and Confirmation of Radio Emission from Both Components
Hallinan, Gregg; Zhang, Qicheng; Golden, Aaron +2 more
Surveys have shown that up to 1/10th of all ultracool dwarfs (UCDs) are appreciable radio emitters, with their emission attributed to a combination of gyrosynchrotron radiation and the electron cyclotron maser instability. 2M J0746+2000AB is a close stellar binary comprised of an L0 and L1.5 dwarf that was previously identified as a source of 5 GH…
The Most Probable 3D Orbit for Spectroscopic Binaries
Docobo, José A.; Campo, Pedro P.; Abushattal, Ahmad A.
Binary stars are a very important source of astronomical information. Those short-period binaries observed by means of both spectroscopy and interferometry can provide, through their corresponding orbits, precise values regarding individual masses as well as orbital parallaxes. For this reason, it is fundamental to attempt to optically resolve dou…
Heliospheric Structure as Revealed by the 3-88 keV H ENA Spectra
Schwadron, N. A.; Pogorelov, N. V.; Zank, G. P. +8 more
Energetic neutral atoms (ENAs) are an important tool for investigating the structure of the heliosphere. Recently, it was observed that fluxes of ENAs (with energy ≤55 keV) coming from the upwind and downwind regions of the heliosphere are similar in strength. This led the authors of these observations to hypothesize that the heliosphere is bubble…
Molecular gas in distant brightest cluster galaxies
Castignani, G.; Combes, F.; Salomé, P. +1 more
The mechanisms governing the stellar mass assembly and star formation history of brightest cluster galaxies (BCGs) are still being debated. By means of new and archival molecular gas observations we investigate the role of dense megaparsec-scale environments in regulating the fueling of star formation in distant BCGs, through cosmic time. We obser…