Search Publications
A New Window into the Nature of X-Ray Binaries in M101 from Their Optical Emission
Chandar, Rupali; Mok, Angus; Gallo, Elena +3 more
The high-energy emission from nearby, star-forming galaxies is dominated by X-ray binaries, where a neutron star or black hole is accreting mass from either a low-mass (≲3 M⊙) or high-mass (≳8 M⊙) star. Donor stars with intermediate masses ≈3-7 M⊙ are also possible, but rarer in our Galaxy. Since it is not possible…
VLT/X-Shooter Spectroscopy of Lyman Break Analogs: Direct-method O/H Abundances and Nitrogen Enhancements
Heckman, Timothy M.; Overzier, Roderik A.; Loaiza-Agudelo, Maryory
We used Very Large Telescope/X-Shooter to target a sample of nearby analogs of Lyman break galaxies (LBGs). These Lyman break analogs are similar to the LBGs in many of their physical properties. We determine electron temperatures using the weak [O III] λ4363 emission line and determine the oxygen abundance (O/H) using the direct and strong-line m…
An Ejecta Kinematics Study of Kepler's Supernova Remnant with High-resolution Chandra HETG Spectroscopy
Sato, Toshiki; Hughes, John P.; Slane, Patrick +6 more
We report our measurements of the bulk radial velocity from a sample of small, metal-rich ejecta knots in Kepler's supernova remnant (SNR). We measure the Doppler shift of the He-like Si Kα line-center energy in the spectra of these knots based on our Chandra High-Energy Transmission Grating Spectrometer observation to estimate their radial veloci…
Assessment of Systematic Uncertainties in the Cosmological Analysis of the SDSS Supernovae Photometric Sample
Scolnic, Dan; Kessler, Richard; Popovic, Brodie
Improvements to the precision of measurements of cosmological parameters with Type Ia supernovae (SNe Ia) are expected to come from large photometrically identified (photometric) supernova (SN) samples. Here we reanalyze the Sloan Digital Sky Survey (SDSS) photometric SN sample, with roughly 700 high-quality, likely but unconfirmed SNe Ia light cu…
Comprehensive photometric investigation of an active early K-type contact system—IL Cancri
Sarotsakulchai, Thawicharat; Liu, Nian-Ping; Rattanasoon, Somsawat +1 more
Comprehensive photometric investigation of the early K-type contact binary IL Cnc was carried out. A few light curves from both ground-based telescopes and the Kepler space telescope were obtained (or downloaded) and then analyzed in detail. They are mostly found to be asymmetric and there are even continuously changing O'Connell effects in the li…
A chromosome map to unveil stellar populations with different magnesium abundances. The case of ω Centauri
Milone, A. P.; Cordoni, G.; Marino, A. F. +7 more
Historically, photometry has been largely used to identify stellar populations [multiple populations (MPs)] in globular clusters (GCs) by using diagrams that are based on colours and magnitudes that are mostly sensitive to stars with different metallicities or different abundances of helium, carbon, nitrogen, and oxygen. In particular, the pseudo-…
Blueshifted absorption lines from X-ray reflection in IRAS 13224-3809
Young, A. J.; Fabian, A. C.; Miller, J. M. +17 more
We explore a disc origin for the highly blueshifted, variable absorption lines seen in the X-ray spectrum of the narrow-line Seyfert 1 galaxy IRAS 13224-3809. The blueshift corresponds to a velocity of ∼0.25c. Such features in other active galactic nuclei are often interpreted as ultrafast outflows. The velocity is of course present in the orbital…
A Gas Giant Planet in the OGLE-2006-BLG-284L Stellar Binary System
Udalski, Andrzej; Mróz, Przemek; Szymański, Michał K. +34 more
We present the analysis of microlensing event OGLE-2006-BLG-284, which has a lens system that consists of two stars and a gas giant planet with a mass ratio of qp = (1.26 ± 0.19) × 10-3 to the primary. The mass ratio of the two stars is qs = 0.289 ± 0.011, and their projected separation is ss = 2.1 ± 0.7…
Discovery of a complex spiral-shell structure around the oxygen-rich AGB star GX Monocerotis
Wittkowski, M.; Kim, H.; Randall, S. K. +4 more
The circumstellar envelopes of asymptotic giant branch (AGB) stars exhibit a wide range of morphologies and chemical compositions that can be exploited to unravel their mass-loss history as well as binary status. Here, we present ALMA Band 6 observations centred upon the oxygen-rich, high mass-loss rate AGB star GX Mon. The resulting CO (2-1) map …
The residence-time of Jovian electrons in the inner heliosphere
Heber, B.; Herbst, K.; Vogt, A. +3 more
Context. Jovian electrons serve an important role in test-particle distribution in the inner heliosphere. They have been used extensively in the past to study the (diffusive) transport of cosmic rays in the inner heliosphere. With new limits on the Jovian source function, that is, the particle intensity just outside the Jovian magnetosphere, and a…