530 research outputs found
Outburst evolution, historic light curve and a flash-ionized nebula around the WZ Sge-type object PNV J03093063+2638031
We have monitored the 2014 superoutburst of the WZ Sge-type transient PNV
J03093063+2638031 for more than four months, from V=11.0 maximum brightness
down to V=18.4 mag, close to quiescence value, by obtaining BVRI photometry and
low resolution fluxed spectroscopy. The evolution was normal and no late-time
`echo' outbursts were observed. The absolute integrated flux of emission lines
kept declining along the superoutburst, and their increasing contrast with the
underlying continuum was simply the result of the faster decline of the
continuum compared to the emission lines. Inspection of historical Harvard
plates covering the 1899-1981 period did not reveal previous outbursts, neither
`normal' nor 'super'. We discovered an extended emission nebula (radius ~1
arcmin) around PNV J03093063+2638031, that became visible for a few months as
the result of photo-ionization from the superoutburst of the central star. It
is not present on Palomar I and II sky survey images and it quickly disappeared
when the outburst was over. From the rate at wich the inization front swept
through the nebula, we derive a distance of ~120 pc to the system. The nebula
is density bounded with an outer radius of 0.03 pc, and the absolute magnitude
of the central star in quiescence is M(V)~14.2 mag. The electron density in the
nebula is estimated to be 10(+5) cm(-3) from the observed recombination time
scale. Given the considerable substructures seen across the nebula, a low
filling factor is inferred. Similar nebulae have not been reported for other WZ
Sge objects and the challenges posed to models are considered.Comment: Astronomy & Astrophysic
Electrospray ion beam deposition plus low-energy electron holography as a tool for imaging individual biomolecules
Inline low-energy electron holography (LEEH) in conjunction with sample preparation by electrospray ion beam deposition (ES-IBD) has recently emerged as a promising method for the sub-nanometre-scale single-molecule imaging of biomolecules. The single-molecule nature of the LEEH measurement allows for the mapping of the molecules' conformational space and thus for the imaging of structurally variable biomolecules, thereby providing valuable complementary information to well-established biomolecular structure determination methods. Here, after briefly tracing the development of inline LEEH in bioimaging, we present the state-of-the-art of native ES-IBD + LEEH as a method of single-protein imaging, discuss its applications, specifically regarding the imaging of structurally flexible protein systems and the amplitude and phase information encoded in a low-energy electron hologram, and provide an outlook regarding the considerable possibilities for the future advancement of the approach
Variable stars in one open cluster within the Kepler/K2-Campaign-5 field: M 67 (NGC 2682)
In this paper we continue the release of high-level data products from the
multiyear photometric survey collected at the 67/92 cm Schmidt Telescope in
Asiago. The primary goal of the survey is to discover and to characterise
variable objects and exoplanetary transits in four fields containing five
nearby open clusters spanning a broad range of ages. This second paper releases
a photometric catalogue, in five photometric bands, of the Solar-age,
Solar-metallicity open cluster M 67 (NGC 2682). Proper motions are derived
comparing the positions observed in 2013 at the Asiago's Schmidt Telescope with
those extracted from [email protected] MPG/ESO images in 2000. We also analyse the
variable sources within M 67. We detected 68 variables, 43 of which are new
detection. Variable periods and proper-motion memberships of a large majority
of sources in our catalogue are improved with respect to previous releases. The
entire catalogue will be available in electronic format. Besides the general
interest on an improved catalogue, this work will be particularly useful
because of: (1) the imminent release of Kepler/K2 Campaign-5 data of this
cluster, for which our catalogue will provide an excellent, high spatial
resolution input list, and (2) characterisation of the M 67 stars which are
targets of intense HARPS and HARPS-N radial-velocity surveys for planet search.Comment: 8 pages, 6 figures (2 at low resolution), 2 tables. Accepted for
publication in MNRAS on October 17, 2015. Electronic materials available at
the url http://groups.dfa.unipd.it/ESPG/M67.html , and later on the Journal
and at the CD
Interstellar Comet 2I/Borisov exhibits a structure similar to native Solar System comets
We processed images taken with the Hubble Space Telescope (HST) to
investigate any morphological features in the inner coma suggestive of a
peculiar activity on the nucleus of the interstellar comet 2I/Borisov. The coma
shows an evident elongation, in the position angle (PA) ~0-180d direction,
which appears related to the presence of a jet originating from a single active
source on the nucleus. A counterpart of this jet directed towards PA ~10d was
detected through analysis of the changes of the inner coma morphology on HST
images taken in different dates and processed with different filters. These
findings indicate that the nucleus is probably rotating with a spin axis
projected near the plane of the sky and oriented at PA ~100d-280d, and that the
active source is lying in a near-equatorial position. Subsequent observations
of HST allowed us to determine the direction of the spin axis at
RA=17h20m+/-15d and Dec = -35d+\-10d.Comment: 5 pages, 6 figures (low resolution). Full-resolution figures and
bonus material at this url
https://web.oapd.inaf.it/bedin/files/PAPERs_eMATERIALs/BORISOV_comet/
Accepted for publication in MNRAS Letters on 2020 April 1st (not a joke ;
The two Ultraluminous X-ray sources in the galaxy NGC 925
NGC 925 ULX-1 and ULX-2 are two ultraluminous X-ray sources in the galaxy NGC
925, at a distance of 8.5 Mpc. For the first time, we analyzed high quality,
simultaneous XMM-Newton and NuSTAR data of both sources. Although at a first
glance ULX-1 resembles an intermediate mass black hole candidate (IMBH) because
of its high X-ray luminosity ( erg s) and its
spectral/temporal features, a closer inspection shows that its properties are
more similar to those of a typical super-Eddington accreting stellar black hole
and we classify it as a `broadened disc' ultraluminous X-ray source. Based on
the physical interpretation of this spectral state, we suggest that ULX-1 is
seen at small inclination angles, possibly through the evacuated cone of a
powerful wind originating in the accretion disc. The spectral classification of
ULX-2 is less certain, but we disfavour an IMBH accreting at sub-Eddington
rates as none of its spectral/temporal properties can be associated to either
the soft or hard state of Galactic accreting black hole binaries.Comment: Accepted on MNRAS with very minor comments, 7 pages, 5 figures, 1
tabl
Asymmetric brain activation: Relation to binge eating in overweight subjects
Right-sided frontal asymmetry has been related to negative affect and an “avoidant” personality type. Research has demonstrated a relationship between right-sided frontal asymmetry and restrained eating in normal weight individuals. It has previously been shown that normal weight restrained eaters display similar frequencies of negative affect and patterns of eating as overweight binge eaters. This study tested the hypothesis that overweight individuals high in binge eating would exhibit greater right-sided frontal asymmetry than would overweight individuals low in binge eating. 30 overweight participants were recruited from a weight maintenance, or binge eating, study. Participants were assessed using the Binge Eating Scale (BES), Mood and Anxiety Symptom Questionnaire (MASQ), Positive and Negative Affect Schedule (PANAS), Power of Food Scale (PFS) and the Three Factor Eating Questionnaire (TFEQ). Asymmetrical brain activation in the frontal and parietal cortices was assessed using resting electroencephalogram (EEG) recordings.Participants were grouped according to BES scores (low binge vs. high binge). ANOVAs were used to examine group differences in asymmetry by region (frontal vs. parietal) with and without controlling for state affect. Pearson correlations were used to examine the relationships between all self-report measures and asymmetrical activation. Results did not support the main hypothesis, indicating that binge eating was not related to asymmetry in this sample. High bingers scored significantly higher in MASQ Anxious Arousal, however, state affect was not related to asymmetry. Post hoc analyses revealed that PFS scores were negatively correlated with positive affect, positively correlated with left-sided frontal asymmetry, and positively correlated with right-sided parietal asymmetry. An inverse correlation was also found between frontal and parietal asymmetry. Post hoc results encourage further investigation into the affect model of frontal asymmetry. It is suggested that the BIS-BAS model of asymmetry may better account for frontal asymmetry results, however data collected in this study did not allow for an evaluation of construct validity of differing theories. Future research is needed to unify asymmetrical activation models and further explore relationships between appetitive responsiveness, frontal asymmetry, and parietal asymmetry.Ph.D., Clinical Psychology -- Drexel University, 200
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