Search Publications

The failed state transition of the ATOLL source GRS 1724-308

Capitanio, F.; Tarana, A.; Cocchi, M.

The 2004-2012 X-ray time history of the NS LMXB GRS 1724-308 shows, along with the episodic brightenings associated with the low-high state transitions typical of the ATOLL sources, a peculiar, long lasting (∼300 d) flaring event, observed in 2008. This rare episode, characterized by a high-flux hard state, has never been observed before for GRS 1…

Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud - III. Horizontal branch morphology

Cohen, Roger E.; Wagner-Kaiser, R.; Sarajedini, Ata +5 more

We leverage new high-quality data from Hubble Space Telescope program GO-14164 to explore the variation in horizontal branch morphology among globular clusters in the Large Magellanic Cloud (LMC). Our new observations lead to photometry with a precision commensurate with that available for the Galactic globular cluster population. Our analysis ind…

Flexion in Abell 2744

Bird, J. P.; Goldberg, D. M.

We present the first flexion-focused gravitational lensing analysis of the Hubble Frontier Field observations of Abell 2744 (z = 0.308). We apply a modified Analytic Image Model technique to measure source galaxy flexion and shear values at a final number density of 82 arcmin^-2. By using flexion data alone, we are able to identify the p…

Discovery of two bright DO-type white dwarfs

Geier, S.; Reindl, Nicole; Østensen, R. H.

We discovered two bright DO-type white dwarfs, GALEX J053628.3+544854 (J0536+5448) and GALEX J231128.0+292935(J2311+2929), which rank among the eight brightest DO-type white dwarfs known. Our non-LTE model atmosphere analysis reveals effective temperatures and surface gravities of {T_eff} = 80000± 4600 K and log g = 8.25± 0.15 for J0536+5448 and {…

The unusual ISM in blue and dusty gas-rich galaxies (BADGRS)

Ivison, R. J.; de Zotti, G.; Dunne, L. +12 more

The Herschel-ATLAS unbiased survey of cold dust in the local Universe is dominated by a surprising population of very blue (FUV-K < 3.5), dust-rich galaxies with high gas fractions (f_H I=M_{H I}/(M_{\ast }+M+_{H I})>0.5). Dubbed `Blue and Dusty Gas-Rich Sources' (BADGRS) they have cold diffuse dust temperatures, and the highest dust-to-stel…

Erratum: Rapid Optical Variations Correlated with X-rays in the 2015 Second Outburst of V404 Cygni (GS 2023+338)

Nogami, Daisaku; Shidatsu, Megumi; Kato, Taichi +24 more

Discovery of two embedded massive YSOs and an outflow in IRAS 18144-1723

Davis, C. J.; Wouterloot, J. G. A.; Varricatt, W. P. +1 more

Massive stars are rarely seen to form in isolation. It has been proposed that association with companions or clusters in the formative stages is vital to their mass accumulation. In this paper, we study IRAS 18144-1723, a massive young stellar object (YSO) that had been perceived in early studies as a single source. In the CO(3-2) line, we detect …

An unusual transient in the extremely metal-poor Galaxy SDSS J094332.35+332657.6 (Leoncino Dwarf)

Sánchez Almeida, J.; Filho, Mercedes E.

We have serendipitously discovered that Leoncino Dwarf, an ultrafaint, low-metallicity record-holder dwarf galaxy, may have hosted a transient source, and possibly exhibited a change in morphology, a shift in the centre of brightness, and peak variability of the main (host) source in images taken approximately 40 yr apart; it is highly likely that…

The onset of convective coupling and freezing in the white dwarfs of 47 Tucanae

Caiazzo, Ilaria; Heyl, Jeremy; Richer, Harvey +3 more

Using images from the Hubble Space Telescope Advanced Camera for Surveys, we measure the rate of cooling of white dwarfs in the globular cluster 47 Tucanae and compare it to modelled cooling curves. We examine the effects of the outer convective envelope reaching the nearly isothermal degenerate core and the release of latent heat during core crys…

General circular velocity relation of a test particle in a 3D gravitational potential: application to the rotation curves analysis and total mass determination of UGC 8490 and UGC 9753

Rosado, M.; Gabbasov, R.; Repetto, P. +1 more

In this paper, we derive a novel circular velocity relation for a test particle in a 3D gravitational potential applicable to every system of curvilinear coordinates, suitable to be reduced to orthogonal form. As an illustration of the potentiality of the determined circular velocity expression, we perform the rotation curves analysis of UGC 8490 …