ترغب بنشر مسار تعليمي؟ اضغط هنا

Eclipsing Binaries in the Young LMC Cluster NGC 1850

101   0   0.0 ( 0 )
 نشر من قبل Stuart Taylor
 تاريخ النشر 2004
  مجال البحث فيزياء
والبحث باللغة English
 تأليف Stuart F. Taylor




اسأل ChatGPT حول البحث

I present light curves for two detached eclipsing binary stars in the region of the LMC cluster NGC 1850, which is possibly a young globular cluster still in formation. One, a likely spectral type O star, is a newly detected eclipsing binary in the region of the very young subcluster NGC 1850A. This binary is among a small number of highly massive O-type stars in binary systems found in LMC clusters. These two eclipsing binaries are the first discovered in the well studied NGC 1850, and the O-type star is the first eclisping binary found in NGC 1850A. Light curves for two NGC 1850 region Cepheid variables are also shown. Discovering two eclipsing binaries in the young globlular-like cluster NGC 1850 is discussed in terms of the importance of the binary fraction to globular cluster evolution.

قيم البحث

اقرأ أيضاً

83 - M. Simon , J. Toraskar 2017
The ages of the components in very short period pre-main sequence (PMS) binaries are essential to an understanding of their formation. We considered a sample of 7 PMS eclipsing binaries (EBs) with ages 1 to 6.3 MY and component masses 0.2 to 1.4 Msun The very high precision with which their masses and radii have been measured, and the capability provided by the {it Modules for Experiments in Stellar Astrophysics (MESA)} to calculate their evolutionary tracks at exactly the measured masses, allows the determination of age differences of the components independent of their luminosities and effective temperatures. We found that the components of 5 EBs, ASAS J052821+0338.5, Parenago 1802, JW 380, CoRoT 223992193, and UScoCTIO 5, formed within 0.3 MY of each other. The parameters for the components of V1174 Ori, imply an implausible large age difference of 2.7 MY and should be reconsidered. The 7th EB in our sample, RX J0529.4+0041 fell outside the applicability of our analysis.
We use photometric and spectroscopic observations of the detached eclipsing binaries V40 and V41 in the globular cluster NGC 6362 to derive masses, radii, and luminosities of the component stars. The orbital periods of these systems are 5.30 and 17.8 9 d, respectively. The measured masses of the primary and secondary components ($M_p$, $M_s$) are (0.8337$pm$0.0063, 0.7947$pm$0.0048) M$_odot$ for V40 and (0.8215$pm$0.0058, 0.7280$pm$0.0047) M$_odot$ for V41. The measured radii ($R_p$, $R_s$) are (1.3253$pm$0.0075, 0.997$pm$0.013) R$_odot$ for V40 and (1.0739$pm$0.0048, 0.7307$pm$0.0046) R$_odot$ for V41. Based on the derived luminosities, we find that the distance modulus of the cluster is 14.74$pm$0.04 mag -- in good agreement with 14.72 mag obtained from CMD fitting. We compare the absolute parameters of component stars with theoretical isochrones in mass-radius and mass-luminosity diagrams. For assumed abundances [Fe/H] = -1.07, [$alpha$/Fe] = 0.4, and Y = 0.25 we find the most probable age of V40 to be 11.7$pm$0.2 Gyr, compatible with the age of the cluster derived from CMD fitting (12.5$pm$0.5 Gyr). V41 seems to be markedly younger than V40. If independently confirmed, this result will suggest that V41 belongs to the younger of the two stellar populations recently discovered in NGC 6362. The orbits of both systems are eccentric. Given the orbital period and age of V40, its orbit should have been tidally circularized some $sim$7 Gyr ago. The observed eccentricity is most likely the result of a relatively recent close stellar encounter.
129 - A. K. Dupree 2017
High-resolution spectroscopic observations were taken of 29 extended main sequence turn-off (eMSTO) stars in the young ($sim$200 Myr) LMC cluster, NGC 1866 using the Michigan/Magellan Fiber System and MSpec spectrograph on the Magellan-Clay 6.5-m tel escope. These spectra reveal the first direct detection of rapidly rotating stars whose presence has only been inferred from photometric studies. The eMSTO stars exhibit H-alpha emission (indicative of Be-star decretion disks), others have shallow broad H-alpha absorption (consistent with rotation $gtrsim $150 km s$^{-1}$), or deep H-alpha core absorption signaling lower rotation velocities ($ lesssim $150 km s$^{-1}$ ). The spectra appear consistent with two populations of stars - one rapidly rotating, and the other, younger and slowly rotating.
Accurate stellar parameters of stars in open clusters can help constrain models of stellar structure and evolution. Here we wish to determine the age and metallicity content of the open cluster NGC 2506. To this end we investigated three detached ecl ipsing binaries (DEBs; V2032, V4, and V5) for which we determined their masses and radii, as well as four red giant branch stars for which we determined their effective temperatures, surface gravities, and metallicities. Three of the stars in the DEBs have masses close to the cluster turn-off mass, allowing for extremely precise age determination. Comparing the values for the masses and radii of the binaries to BaSTI isochrones we estimated a cluster age of $2.01 pm 0.10$ Gyr. This does depend on the models used in the comparison, where we have found that the inclusion of convective core-overshooting is necessary to properly model the cluster. From red giant branch stars we determined values for the effective temperatures, the surface gravities, and the metallicities. From these we find a cluster metallicity of $-0.36 pm 0.10$ dex. Using this value and the values for the effective temperatures we determine the reddening to be E$(b - y) = 0.057 pm 0.004$ mag. Furthermore, we derived the distance to the cluster from Gaia parallaxes and found $3.101 pm 0.017$ kpc, and we have performed a radial velocity membership determination for stars in the field of the cluster. Finally, we report on the detection of oscillation signals in $gamma$ Dor and $delta$ Scuti members in data from the TESS mission, including the possible detection of solar-like oscillations in two of the red giants.
We present a method for solving the lightcurve of an eclipsing binary system which contains a Cepheid variable as one of its components as well as the solutions for three eclipsing Cepheids in the Large Magellanic Cloud (LMC). A geometric model is co nstructed in which the component stars are assumed to be spherical and on circular orbits. The emergent system flux is computed as a function of time, with the intrinsic variations in temperature and radius of the Cepheid treated self-consistently. Fitting the adopted model to photometric observations, incorporating data from multiple bandpasses, yields a single parameter set best describing the system. This method is applied to three eclipsing Cepheid systems from the MACHO Project LMC database: MACHO IDs 6.6454.5, 78.6338.24 and 81.8997.87. A best-fit value is obtained for each systems orbital period and inclination and for the relative radius, color and limb-darkening coefficients of each star. Pulsation periods and parameterizations of the intrinsic color variations of the Cepheids are also obtained and the amplitude of the radial pulsation of each Cepheid is measured directly. The system 6.6454.5 is found to contain a 4.97-day Cepheid, which cannot be definitely classified as Type I or Type II, with an unexpectedly brighter companion. The system 78.6338.24 consists of a 17.7-day, W Vir Class Type II Cepheid with a smaller, dimmer companion. The system 81.8997.87 contains an intermediate-mass, 2.03-day overtone Cepheid with a dimmer, red giant secondary.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا