Recent studies of the near-infrared (NIR) properties of dwarf irregular galaxies (dIs) and blue compact dwarfs (BCDs) have provided improved estimates for the NIR luminosity of old stellar ...populations in these galaxies. These can be used to derive gas fractions, and thereby to evaluate how BCDs have evolved with respect to dIs. Oxygen abundances have been derived for four BCDs in the Virgo Cluster from a run at Gemini-North in 2003. Combining these new abundances with published values, we study the correlations among the metallicity, Ks luminosity, gas mass, baryonic mass, and gas fraction. Within errors, the two types of dwarfs appear to share a common relation between the oxygen abundance and the luminosity in Ks. The correlation between metallicity and the gas fraction is the same for BCDs as for dIs, indicating that BCD evolution has been similar to dIs. Since dIs appear to have evolved as isolated systems, the BCD bursts are unlikely to be a consequence of gas infall or merging.
We report on the follow-up and recovery of 100 program NEAs, PHAs and VIs
using the ESO/MPG 2.2m, Swope 1m and INT 2.5m telescopes equipped with large
field cameras. The 127 fields observed during 11 ...nights covered 29 square
degrees. Using these data, we present the incidental survey work which includes
558 known MBAs and 628 unknown moving objects mostly consistent with MBAs from
which 58 objects became official discoveries. We planned the runs using six
criteria and four servers which focus mostly on faint and poorly observed
objects in need of confirmation, follow-up and recovery. We followed 62 faint
NEAs within one month after discovery and we recovered 10 faint NEAs having big
uncertainties at their second or later opposition. Using the INT we eliminated
4 PHA candidates and VIs. We observed in total 1,286 moving objects and we
reported more than 10,000 positions. All data were reduced by the members of
our network in a team effort, and reported promptly to the MPC. The positions
of the program NEAs were published in 27 MPC and MPEC references and used to
improve their orbits. The O-C residuals for known MBAs and program NEAs are
smallest for the ESO/MPG and Swope and about four times larger for the INT
whose field is more distorted. The incidental survey allowed us to study
statistics of the MBA and NEA populations observable today with 1--2m
facilities. We calculate preliminary orbits for all unknown objects,
classifying them as official discoveries, later identifications and unknown
outstanding objects. The orbital elements a, e, i calculated by FIND_ORB
software for the official discoveries and later identified objects are very
similar with the published elements which take into account longer
observational arcs; thus preliminary orbits were used in statistics for the
whole unknown dataset. (CONTINUED)
The dust ejecta of Main-Belt Comet P/2010 A2 (LINEAR) have been observed with several telescopes at the at the Observatorio del Roque de los Muchachos on La Palma, Spain. Application of an inverse ...dust tail Monte Carlo method to the images of the dust ejecta from the object indicates that a sustained, likely water-ice driven, activity over some eight months is the mechanism responsible for the formation of the observed tail. The total amount of dust released is estimated to be 5E7 kg, which represents about 0.3% of the nucleus mass. While the event could have been triggered by a collision, this cannot be decided from the currently available data.
We present comprehensive multiwavelength observations of three gamma-ray bursts (GRBs) with durations of several thousand seconds. We demonstrate that these events are extragalactic transients; in ...particular we resolve the long-standing conundrum of the distance of GRB 101225A (the "Christmas-day burst"), finding it to have a redshift z=0.847, and showing that two apparently similar events (GRB 111209A and GRB 121027A) lie at z=0.677 and z=1.773 respectively. The systems show extremely unusual X-ray and optical lightcurves, very different from classical GRBs, with long lasting highly variable X-ray emission and optical light curves that exhibit little correlation with the behaviour seen in the X-ray. Their host galaxies are faint, compact, and highly star forming dwarf galaxies, typical of "blue compact galaxies". We propose that these bursts are the prototypes of a hitherto largely unrecognized population of ultra-long GRBs, that while observationally difficult to detect may be astrophysically relatively common. The long durations may naturally be explained by the engine driven explosions of stars of much larger radii than normally considered for GRB progenitors which are thought to have compact Wolf-Rayet progenitor stars. However, we cannot unambiguously identify supernova signatures within their light curves or spectra. We also consider the alternative possibility that they arise from the tidal disruption of stars by supermassive black holes.
A sample of 16 blue compact dwarf galaxies (BCDs) in the Virgo Cluster has been imaged in the near-infrared (NIR) in \(J\) and \(K_s\) on the 2.1m telescope at OAN-SPM in Mexico. Isophotes as faint ...as \(\mu_J\) = 24 mag arcsec\(^{-2}\) and \(\mu_{K_s}\) = 23 mag arcsec\(^{-2}\) have been reached in most of the targets. Surface brightness profiles can be fitted across the whole range of radii by the sum of two components: a hyperbolic secant (sech) function, which is known to fit the light profiles of dIs, and a Gaussian component, which quantifies the starburst near the centre. Isophotal and total fitted NIR magnitudes have been calculated, along with semimajor axes at \(\mu_J\) = 23 mag arcsec\(^{-2}\) and \(\mu_{K_s}\) = 22 mag arcsec\(^{-2}\). The diffuse underlying component and the young starburst have been quantified using the profile fitting. Most color profiles show a constant color, between \(J-K_s\)=0.7 to 0.9 mag. The diffuse component represents the overwhelming majority of the NIR light for most BCDs, the starburst enhancing the flux by less than about 0.3 mag. Linear correlations were found between the sech scale length and the sech magnitude, and between the sech semimajor axis and the sech magnitude. Overall, galaxies with more luminous diffuse components are larger and brighter in the centre. The central burst correlates with the diffuse component, with brighter BCDs having stronger star-bursts, suggesting that more massive objects are forming stars more efficiently. BCDs lie on the ``fundamental plane'' defined by dwarf irregulars (dISs) in Paper I, following the same relation between sech absolute magnitude, sech central surface brightness, and the hydrogen line-width \(W_{20}\), although the scatter is larger than for the dIs. one sentence cut
Asteroid pairs sharing similar heliocentric orbits were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide ...additional insight into their formation mechanism. A previously hypothesized rotational fission process4 may explain their formation - critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs revealing that primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system which subsequently disrupts under its own internal system dynamics soon after formation.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
In advanced stages of dilated cardiomyopathy (DCM), both atrial function and left ventricle (LV) myocardial mechanics are ...blunted. Left atrial reservoir strain (LASr) is a sensitive parameter for left atrial (LA) function evaluation. Our study aimed to find a correlation between LASr depression and rotational parameters damage in patients with DCM, using 4-Dimensional automated LA and LV quantification.
Methods
We enrolled 75 patients with DCM and narrow QRS and 30 healthy volunteers. The evaluation consisted of clinical examination, laboratory tests, 12 leads electrocardiography. All participants underwent a complete transthoracic echocardiogram to determine cardiac structure and function according to the current guidelines. Measurement of LA and LV strain was performed using 4D Auto-quantification software. The study evaluated LASr by 4D Auto Atrial Quantification. 4D LV Quantification measured twist and torsion.
Results
1. We divided the patients into two groups: 27 with DCM and atrial fibrillation (AF) and 48 with DCM and sinus rhythm (SR). 2. Mean values of LASr were 10.20 in patients with DCM and 30.36 in the healthy volunteers’ group. (P<0.0001). Rotational parameters were LV twist=1.66, LV torsion=0.44 in DCM patients, LV twist=10.1, and LV torsion=1,73 in the healthy group. (P<0.0001). In DCM patients with AF, mean values were lower ( LASr =9.52, LV twist=0.97, LV torsion=0.28, LV torsion=0.4) than in patients with SR (LASr=10.59, LVtwist=1.93, LV torsion=0.5) 3. A correlation was found between LASr and LV twist (r=-0.8), between LASr and torsion (r=-0.78), in patients with AF, and also in those with DCM and SR ( r=-0.74 for the twist, r=-0.73 for torsion).
Conclusions
1. LASr reduction was related to rotational damage of the left ventricle in DCM patients. 2. LASr, LV twist, and LV torsion were lower in cases with AF. 3. LA function is a parameter of chronic increased LV filling pressure. The correlation between LASr decrease and anomalies of twist and torsion may suggest a link between increased LV filling pressure and rotational dysfunction in patients with dilated cardiomyopathy phenotype.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
4D echocardiography is a useful tool to identify both decreasing of mitral annular excursion (MAE) and left ventricle (LV) ...strain damage in patients with dilated cardiomyopathy (DCM). Our study aimed to identify a correlation between MAE decreasing and LV strain parameters in patients with DCM.
Methods
We enrolled 75 patients with DCM and 30 healthy volunteers. The evaluation consisted of clinical examination, laboratory tests, 12 leads electrocardiography. All participants underwent a complete transthoracic echocardiogram to determine cardiac structure and function according to the current guidelines. The study evaluated MAE by 4D Auto Mitral Valve Quantification (4D - MVQ). 4D LV Quantification (4D-LVQ) measured global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS), and global radial strain (GRS).
Results
1. We divided the patients into two groups: 27 with DCM and atrial fibrillation (AF) and 48 with DCM and sinus rhythm (SR). 2. Mean values of MAE were 3.89 (SD=2.2, CV=0.56) in patients with DCM and 11.1 (SD 1.08, CV 0.09) in the healthy volunteers’ group. (P<0.0001). In patients with DCM and RS MAE mean value was 4.24 (SD=2.34, CV=0.54), and in the AF group was 2.98 (SD=1.38, CV=0.45) (p = 0.0125). 3. Mean values of strain in patients with DCM and RS compared with those in AF were: GLS −6,63 vs. −4,1 (P = 0.0005), GCS −6.08 vs. −5,2 (P = 0.1931), GAS −11.22 vs. −8.47 (P = 0.0181), GRS = 14.5 vs. 10.89 (P = 0.0493). 4. The correlations obtained between MAE and LV strain in patients with DCM were: GLS (r=-0.67), GAS (r=-0.61), GRS (r=0.5), and GCS (r=-0.39).
Conclusions
1. MAE was significantly reduced in patients with DCM compared with healthy volunteers. 2. The patients with DCM and AF presented the lowest values of MAE and LV global strain parameters. 3. MAE correlated better with GLS and GAS, moderate with GRS, and weak with GAS in patients with dilated cardiomyopathy phenotype.
