اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدDiscovery of the spectroscopic binary nature of the classical Cepheids FN Aql and V1344 Aql
203
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We present the analysis of photometric and spectroscopic data of two classical Cepheids, FN Aquilae and V1344 Aquilae. Based on the joint treatment of the new and earlier radial velocity data, both Galactic Cepheids have been found to be a member in a spectroscopic binary system. To match the phases of the earlier radial velocity data correctly with the new ones, we also determined the temporal behaviour of the pulsation period of these Cepheids based on all available photometric data. The O-C graph covering about half century shows slight changes in the pulsation period due to stellar evolution for both Cepheids.
قيم البحث
اقرأ أيضاً
We present new spectroscopic observations of the early type, double-lined eclipsing binary V1441,Aql. The radial velocities and the available photometric data obtained by $ASAS$ is analysed for deriving the parameters of the components. The component
s of V1441,Aql are shown to be a B3,IV primary with a mass M$_p$=8.02$pm$0.51 M$_{odot}$ and radius R$_p$=7.33$pm$0.19 R$_{odot}$ and a B9 III secondary with a mass M$_s$=1.92$pm$0.14 M$_{odot}$ and radius R$_s$=4.22$pm$0.11 R$_{odot}$. Our analyses show that V1441,Aql is a double-contact system with rapidly rotating components. Based on the position of the components plotted on the theoretical Hertzsprung-Russell diagram, we estimate that the ages of V1441,Aql is about 30,Myr, neglecting the effects of mass exchange between the components. Using the UBVJHK magnitudes and interstellar absorption we estimated the mean distance to the system V1441,Aql as 550$pm$25,pc.
X-ray bursts have recently been discovered in the Cepheids $delta$ Cep and $beta$ Dor modulated by the pulsation cycle. We have obtained an observation of the Cepheid $eta$ Aql with the XMM-Newton satellite at the phase of maximum radius, the phase a
t which there is a burst of X-rays in $delta$ Cep. No X-rays were seen from the Cepheid $eta$ Aql at this phase, and the implications for Cepheid upper atmospheres are discussed. We have also used the combination of X-ray sources and Gaia and 2MASS data to search for a possible grouping around the young intermediate mass Cepheid. No indication of such a group was found.
We present an in-depth photometric study of the 2013 superoutburst of the recently discovered cataclysmic variable V1838 Aql and subsequent photometry near its quiescent state. A careful examination of the development of the superhumps is presented.
Our best determination of the orbital period is Porb = 0.05698(9) days, based on the periodicity of early superhumps. Comparing the superhump periods at stages A and B with the early superhump value we derive a period excess of {epsilon} = 0.024(2) and a mass ratio of q = 0.10(1). We suggest that V1838 Aql is approaching the orbital period minimum and thus has a low-mass star as a donor instead of a sub-stellar object.
We report on the recovery of the six old novae EL Aql, V606 Aql, V908 Oph, V1149 Sgr, V1583 Sgr and V3964 Sgr, using photometric and spectroscopic data. Analysing several properties, we find that EL Aql is a good candidate for an intermediate polar.
Furthermore, the system inclination of EL Aql, V606 Aql, V1583 Sgr and V3964 Sgr appears to be sufficiently high to suggest them as good targets for time series observations. We also eliminate some previously suggested candidates for the post-novae V1301 Aql and V1151 Sgr.
The importance of shocks in nova explosions has been highlighted by Fermis discovery of gamma-ray producing novae. Over three years of multi-band VLA radio observations of the 2010 nova V1723 Aql show that shocks between fast and slow flows within th
e ejecta led to the acceleration of particles and the production of synchrotron radiation. Soon after the start of the eruption, shocks in the ejecta produced an unexpected radio flare, resulting in a multi-peaked radio light curve. The emission eventually became consistent with an expanding thermal remnant with mass $2 times 10^{-4} M_odot$ and temperature $10^4$ K. However, during the first two months, the $gtrsim 10^6$ K brightness temperature at low frequencies was too high to be due to thermal emission from the small amount of X-ray producing shock-heated gas. Radio imaging showed structures with velocities of 400 km s$^{-1}$ (d/6 kpc) in the plane of the sky, perpendicular to a more elongated 1500 km s$^{-1}$ (d/6 kpc) flow. The morpho-kinematic structure of the ejecta from V1723 Aql appears similar to nova V959 Mon, where collisions between a slow torus and a faster flow collimated the fast flow and gave rise to gamma -ray producing shocks. Optical spectroscopy and X-ray observations of V1723 Aql during the radio flare are consistent with this picture. Our observations support the idea that shocks in novae occur when a fast flow collides with a slow collimating torus. Such shocks could be responsible for hard X-ray emission, gamma -ray production, and double-peaked radio light curves from some classical novae.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
