Search Publications
Unveiling kinematic structure in the starburst heart of NGC 253
Turner, Jean L.; Consiglio, S. Michelle; Cohen, Daniel P.
We observed the Brackett α emission line (4.05 µm) within the nuclear starburst of NGC 253 to measure the kinematics of ionized gas, and distinguish motions driven by star formation feedback from gravitational motions induced by the central mass structure. Using NIRSPEC on Keck II, we obtained 30 spectra through a 0.5 arcsec slit stepped acr…
K2-280 b - a low density warm sub-Saturn around a mildly evolved star
Cochran, William D.; Endl, Michael; Jordán, Andrés +57 more
We present an independent discovery and detailed characterization of K2-280 b, a transiting low density warm sub-Saturn in a 19.9-d moderately eccentric orbit (e = $0.35_{-0.04}^{+0.05}$ ) from K2 campaign 7. A joint analysis of high precision HARPS, HARPS-N, and FIES radial velocity measurements and K2 photometric data indicates that K2-280 b has…
Li-rich giant stars under scrutiny: binarity, magnetic activity, and the evolutionary status after Gaia DR2
Castro, M.; da Costa, J. S.; de Almeida, L. +2 more
We present a study of the evolutionary state of a few lithium-rich giant stars based on the Gaia Data Release 2 (DR2) parallaxes and photometry. We also investigate the chromospheric activity, the presence of a surface magnetic field, and the radial velocity for our sample stars. We analysed both archive and new data. We gathered archive spectra f…
High-velocity interstellar absorption associated with the supernova remnant W28
Ritchey, Adam M.
We present an analysis of moderately high-resolution optical spectra obtained for the sightline to CD-23 13777, an O9 supergiant that probes high-velocity interstellar gas associated with the supernova remnant W28. Absorption components at both high positive and high negative velocity are seen in the interstellar Na I D and Ca II H and K lines tow…
Which stars can see Earth as a transiting exoplanet?
Kaltenegger, L.; Pepper, J.
Transit observations have found the majority of exoplanets to date. Also spectroscopic observations of transits and eclipses are the most commonly used tool to characterize exoplanet atmospheres and will be used in the search for life. However, an exoplanet's orbit must be aligned with our line of sight to observe a transit. Here, we ask, from whi…
Absolute parameters of three southern eclipsing binaries: DQ Car, BK Ind, and V4396 Sgr
Erdem, Ahmet; Sürgit, Derya; Engelbrecht, Chris A. +1 more
We present combined photometric and spectroscopic analyses of the three southern eclipsing binary stars: DQ Car, BK Ind, and V4396 Sgr. Radial velocity curves of these three systems were obtained at the South African Astronomical Observatory, and their light curves from the available data bases and surveys were used for the analysis. 75 new times …
The effect of pulsation on the near-ultraviolet spectrum of AGB stars
Guerrero, Martín A.; Ortiz, Roberto
Pulsating and non-pulsating asymptotic giant branch (AGB) stars exhibit a variable near-ultraviolet (near-UV) spectrum, which suggest that mechanisms other than pulsation may affect their near-UV spectrum. In this work, we analyse the near-UV spectra of two groups of AGB stars: (1) regularly pulsating and (2) irregular, small-amplitude stars. Near…
H-He collision-induced satellite in the Lyman α profile of DBA white dwarf stars
Xu, Siyi; Hubeny, Ivan; Kielkopf, John F. +6 more
The spectra of helium-dominated white dwarf stars with hydrogen in their atmosphere present a distinctive broad feature centred around 1160 Å in the blue wing of the Lyman α line. It is extremely apparent in WD 1425+540 recently observed with Hubble Space Telescope(HST) Cosmic Origins Spectrograph (COS). With new theoretical line profiles based on…
Modelling of 35-d superorbital cycle of B and V light curves of IMXB HZ Her/Her X-1
Klochkov, D.; Bikmaev, I. F.; Wilms, J. +13 more
The X-ray binary Her X-1 consists of an accreting neutron star and the optical component HZ Her. The 35-d X-ray superorbital variability of this system is known, since its discovery in 1972 by the Uhuru satellite and is believed to be caused by forced precession of a warped accretion disc tilted to the orbital plane. We argue that the observed fea…
Wide-field study of the peculiar globular cluster system hosted by the field lenticular NGC 1172
Salinas, Ricardo; Gómez, Matías; Caso, Juan Pablo +2 more
We present a wide-field study of the globular cluster system (GCS) of the field lenticular galaxy NGC 1172, based on observations from Gemini Multi-Object Spectrograph/Gemini (optical), FourStar/Magellan (NIR), and archival data from ACS/Hubble Space Telescope (optical). This analysis covers the full extension of the GCS, and results in a value of…