Search Publications
Reconciling Optical and Radio Observations of the Binary Millisecond Pulsar PSR J1640+2224
Deller, Adam T.; Kaplan, David L.; Istrate, Alina G. +3 more
Previous optical and radio observations of the binary millisecond pulsar PSR J1640+2224 have come to inconsistent conclusions about the identity of its companion, with some observations suggesting that the companion is a low-mass helium-core (He-core) white dwarf (WD), while others indicate that it is most likely a high-mass carbon-oxygen (CO) WD.…
Detailed chemical abundance analysis of the thick disk star cluster Gaia 1
Kunder, Andrea; Hansen, Terese T.; Koch, Andreas
Star clusters, particularly those objects in the disk-bulge-halo interface are as yet poorly charted, despite the fact that they carry important information about the formation and the structure of the Milky Way. Here, we present a detailed chemical abundance study of the recently discovered object Gaia 1. Photometry has previously suggested it as…
Actions Are Weak Stellar Age Indicators in the Milky Way Disk
Bedell, Megan; Ness, Melissa K.; Beane, Angus
The orbital properties of stars in the Milky Way disk are signatures of their formation, but they are also expected to change over time due to the dynamical evolution of the Galaxy. Stellar orbits can be quantified by the three dynamical actions, J r , L z , and J z , which provide measures of the orbital eccent…
Herschel Spectroscopy of the Taffy Galaxies (UGC 12914/12915 = VV 254): Enhanced [C II] Emission in the Collisionally Formed Bridge
Boulanger, F.; Falgarone, E.; Helou, G. +17 more
Using the PACS and SPIRE spectrometers on board Herschel, we obtained observations of the Taffy galaxies (UGC 12914/12915) and bridge. The Taffy system is believed to be the result of a face-on collision between two gas-rich galaxies, in which the stellar disks passed through each other, but the gas was dispersed into a massive H I and molecular b…
An atlas of cool supergiants from the Magellanic Clouds and typical interlopers. A guide for the classification of luminous red stars
Negueruela, Ignacio; González-Fernández, Carlos; Dorda, Ricardo +1 more
We present an atlas composed of more than 1500 spectra of late-type stars (spectral types from G to M) observed simultaneously in the optical and calcium triplet spectral ranges. These spectra were obtained as part of a survey to search for cool supergiants in the Magellanic Clouds and were taken over four epochs. We provide the spectral and lumin…
Mars Initial Reference Ionosphere (MIRI) Model: Updates and Validations Using MAVEN, MEX, and MRO Data Sets
Withers, Paul; Mayyasi, Majd; Mendillo, Michael +7 more
The Mars Initial Reference Ionosphere (MIRI) model is a semiempirical formulation designed to provide climatological estimates of key parameters of the Martian ionosphere. For the new MIRI-2018 version, an expanded database is used from the Mars Express/Mars Advanced Radar for Subsurface and Ionosphere Sounding/Active Ionospheric Sounding (MEX/MAR…
Spectroscopic and photometric study of the eclipsing interacting binary V495 Centauri
Mennickent, R. E.; Djurašević, G.; Curé, M. +2 more
Double Periodic Variables (DPV) are among the new enigmas of semidetached eclipsing binaries. These are intermediate-mass binaries characterized by a long photometric period lasting on average 33 times the orbital period. We present a spectroscopic and photometric study of the DPV V495 Cen based on new high-resolution spectra and the ASAS V-band l…
Stellar Variability at the Main-sequence Turnoff of the Intermediate-age LMC Cluster NGC 1846
Contreras Ramos, R.; Vivas, A. K.; Strader, J. +2 more
Intermediate-age (IA) star clusters in the Large Magellanic Cloud (LMC) present extended main-sequence turn-offs (MSTO) that have been attributed to either multiple stellar populations or an effect of stellar rotation. Recently it has been proposed that these extended main sequences can also be produced by ill-characterized stellar variability. He…
The root of a comet tail: Rosetta ion observations at comet 67P/Churyumov-Gerasimenko
Behar, E.; Nilsson, H.; Goetz, C. +7 more
Context. The first 1000 km of the ion tail of comet 67P/Churyumov-Gerasimenko were explored by the European Rosetta spacecraft, 2.7 au away from the Sun.
Aims: We characterised the dynamics of both the solar wind and the cometary ions on the night-side of the comet's atmosphere.
Methods: We analysed in situ ion and magnetic field measure…
An Anisotropic Cosmic-Ray Enhancement Event on 07-June-2015: A Possible Origin
Usoskin, Ilya G.; Gil, Agnieszka; Mishev, Alexander +3 more
A usual event, called anisotropic cosmic-ray enhancement (ACRE), was observed as a small increase (≤5 % ) in the count rates of polar neutron monitors during 12 - 19 UT on 07 June 2015. The enhancement was highly anisotropic, as detected only by neutron monitors with asymptotic directions in the southwest quadrant in geocentric solar ecliptic (GSE…