130,664 research outputs found
On the 3–5 μm variability of young variables in Vela-D through Spitzer-WISE observations
No full textFlux variability is a common feature of Young Stellar Objects (YSOs),
which is often related to intermittent events of disk accretion (EXors events in case of
3–4 magnitudes variations). Recently, thanks to the surveys
carried out by the space missions Spitzer and WISE, it has
become possible to perform statistical studies on the mid-IR
variability on large samples of YSOs. As a follow-up
of our recent statistical study on five star forming regions
(Antoniucci et al., Astrophys. J. 782:51, 2014), we present
the 3–5 μm variability study of the YSOs population of the
Vela-D star forming region. We have compared the 3.6 μm
and 4.5 μm Spitzer-IRAC fluxes of 181 YSOs in Vela-D with
their WISE fluxes at 3.4 μm and 4.6 μm and selected those
objects simultaneously varying in both bands. We have iden-
tified a robust sample of 34 variables. On the base of the in-
frared excess of the Spectral Energy Distribution (SED) and
the magnitude vs. color variations, we select 5 EXors can-
didates, which will be systematically monitored to firmly
ascertain their nature. The selected 34 variables represent
∼18 % of the YSOs detected with Spitzer and WISE, a per-
centage higher than that of other young star forming regions.
Conversely, the percentage of candidate EXors (2.7 %) is
quite similar to that measured in Perseus, Ophiuchus and
Serpens, and also equals that found in Vela-D on the base
of Spitzer variability (Giannini et al., Astrophys. J. 704:606,
2009). Consistently with our finding presented in Antoni-
ucci et al. (2014), this fraction equals the probability of ob-
serving the source once in burst and once in quiescence, un-
der the hypothesis that the time elapsed between the two
events is of about 0.5–1 year. Of the 5 selected EXors candi-
dates, 3 are Class I sources, and 2 are flat-spectrum sources,
a circumstance that suggests that accretion-driven variabil-
ity is a common phenomenon during the earlier phases of
the protostellar evolution. In the light of the new WISE data,
we also re-examine a sample of 10 variables, which we had
already selected in Giannini et al. (2009). From the inspec-
tion of their light curves, we select two flat-spectrum sources
as the best EXors candidates
Transient left ventricular apical ballooning syndrome after inadvertent epidural administration of potassium chloride
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Mechanisms affecting platelet response to antiplatelet therapy in patients with ST-segment elevation myocardial infarction.
No full textDeterminans of final infarct size and incidence of aborted infarction in patients treated with primary coronary intervention and adjunctive abciximab therapy
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Left ventricular remodeling and heart failure in diabetic patients treated with primary angioplasty for acute myocardial infarction
No full textLeft ventricular tract obstruction and severe mitral regurgitation in stress-induced cardiomyopathy
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