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Register a new userAbsolute Parameters of Young Stars: PU Pup
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We present combined photometric and spectroscopic analyses of the southern binary star PU Pup. High-resolution spectra of this system were taken at the University of Canterbury Mt. John Observatory in the years 2008 and again in 2014-15. We find the light contribution of the secondary component to be only $sim$2% of the total light of the system in optical wavelengths, resulting in a single-lined spectroscopic binary. Recent TESS data revealed grazing eclipses within the light minima, though the tidal distortion, examined also from HIPPARCOS data, remains the predominating light curve effect. Our model shows PU Pup to have the more massive primary relatively close to filling its Roche lobe. PU Pup is thus approaching the rare `fast phase of interactive (Case B) evolution. Our adopted absolute parameters are as follows: $M_1$ = 4.10 ($pm$0.20) M$_{odot}$, $M_2$ = 0.65 ($pm$0.05) M$_{odot}$, $R_{1}$ = 6.60 ($pm$0.30) R$_{odot}$, $R_2$ = 0.90 ($pm$0.10) R$_{odot}$; $T_{1}$ = 11500 ($pm$500) K, $T_{2}$ = 5000 ($pm$350) K; photometric distance = 186 ($pm$20) pc, age = 170 ($pm$20) My. The less-massive secondary component is found to be significantly oversized and overluminous compared to standard Main Sequence models. We discuss this discrepancy referring to heating from the reflection effect.
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New spectrometric data on V Pup are combined with satellite photometry (HIPPARCOS and recent TESS) to allow a revision of the absolute parameters with increased precision. We find: $M_1$ = 14.0$pm$0.5, $M_2$ = 7.3$pm$0.3 (M$_odot$); $R_{1}$ = 5.48$pm$0.18, $R_2$ = 4.59$pm$0.15 (R$_odot$); $T_{1}$ 26000$pm 1000$, $T_2$ 24000 $pm$1000 (K), age 5 $pm$1 (Myr), photometric distance 320 $pm$10 (pc). The TESS photometry reveals low-amplitude ($sim$0.002 mag) variations of the $beta$ Cep kind, consistent with the deduced evolutionary condition and age of the optical primary. This fact provides independent support to our understanding of the system as in a process of Case A type interactive evolution that can be compared with $mu^1$ Sco. The $sim$10 M$_{odot}$ amount of matter shed by the over-luminous present secondary must have been mostly ejected from the system rather than transferred, thus taking angular momentum out of the orbit and keeping the pair in relative close proximity. New times of minima for V Pup have been studied and the results compared with previous analyses. The implied variation of period is consistent with the Case A evolutionary model, though we offer only a tentative sketch of the original arrangement of this massive system. We are not able to confirm the previously reported cyclical variations having a 5.47 yr period with the new data, though a direct comparison between the HIPPARCOS and TESS photometry points to the presence of third light from a star that is cooler than those of the close binary, as mentioned in previous literature.
We constructed a Hubble Space Telescope (HST) astro-photometric catalog of the central region of the Galactic globular cluster NGC 1261. This catalog, complemented with Gaia DR2 data sampling the external regions, has been used to estimate the structural parameters of the system (i.e., core, half-mass, tidal radii and concentration) from its resolved star density profile. We computed high-precision proper motions thanks to multi-epoch HST data and derived the cluster velocity dispersion profile in the plane of the sky for the innermost region, finding that the system is isotropic. The combination with line-of-sight information collected from spectroscopy in the external regions provided us with the cluster velocity dispersion profile along the entire radial extension. We also measured the absolute proper motion of NGC 1261 using a few background galaxies as a reference. The radial distribution of the Blue Straggler Star population shows that the cluster is in a low/intermediate phase of dynamical evolution.
The photometric and spectroscopic data for three double-lined detached eclipsing binaries were collected from the photometric and spectral surveys. The light and radial velocity curves of each binary system were simultaneously analyzed by using Wilson-Devinney (WD) code, and the absolute physical and orbital parameters of these binaries were derived. The masses of both components of ASASSN-V J063123.82+192341.9 were found to be $M_1 = 1.088 pm 0.016$ and $M_2 = 0.883 pm 0.016 M_{odot}$; and those of ASAS J011416+0426.4 were determined to be $M_1 = 0.934 pm 0.046$ and $M_2 = 0.754 pm 0.043 M_{odot}$; those of MW Aur were derived to be $M_1 = 2.052 pm 0.196$ and $M_2 = 1.939 pm 0.193 M_{odot}$. At last, the evolutionary status of these detached binaries was discussed based on their absolute parameters and the theoretical stellar models. Keywords: Stars: binaries: eclipsing $-$ stars: fundamental parameters$-$ stars: evolution $-$ stars: individual: ASASSN-V J063123.82+192341.9, ASAS J011416+0426.4 and MW Aur
High-resolution spectroscopy is a powerful tool to study the dynamical structure of pulsating stars atmosphere. We aim at comparing the line asymmetry and velocity of the two delta Sct stars rho Pup and DX Cet with previous spectroscopic data obtained on classical Cepheids and beta Cep stars. We obtained, analysed and discuss HARPS high-resolution spectra of rho Pup and DX Cet. We derived the same physical quantities as used in previous studies, which are the first-moment radial velocities and the bi-Gaussian spectral line asymmetries. The identification of f=7.098 (1/d) as a fundamental radial mode and the very accurate Hipparcos parallax promote rho Pup as the best standard candle to test the period-luminosity relations of delta Sct stars. The action of small-amplitude nonradial modes can be seen as well-defined cycle-to-cycle variations in the radial velocity measurements of rho Pup. Using the spectral-line asymmetry method, we also found the centre-of-mass velocities of rho Pup and DX Cet, V_gamma = 47.49 +/- 0.07 km/s and V_gamma = 25.75 +/- 0.06 km/s, respectively. By comparing our results with previous HARPS observations of classical Cepheids and beta Cep stars, we confirm the linear relation between the atmospheric velocity gradient and the amplitude of the radial velocity curve, but only for amplitudes larger than 22.5 km/s. For lower values of the velocity amplitude (i.e., < 22.5 km/s), our data on rho Pup seem to indicate that the velocity gradient is null, but this result needs to be confirmed with additional data. We derived the Baade-Wesselink projection factor p = 1.36 +/- 0.02 for rho Pup and p = 1.39 +/- 0.02 for DX Cet. We successfully extended the period-projection factor relation from classical Cepheids to delta Scuti stars.
We report the results of a long-term spectroscopic monitoring of the A-type supergiant with the B[e] phenomenon 3 Pup = HD 62623. We confirm earlier findings that it is a binary system. The orbital parameters were derived using cross-correlation of the spectra in a range of 4460-4632 A, which contains over 30 absorption lines. The orbit was found circular with a period of $137.4pm0.1$ days, radial velocity semi-amplitude $K_{1} = 5.0pm0.8$ km s$^{-1}$, systemic radial velocity $gamma = +26.4pm2.0$ km s$^{-1}$, and the mass function $f(m) = (1.81^{+0.97}_{-0.76})times10^{-3}$ M$_{odot}$. The object may have evolved from a pair with initial masses of $sim$6.0 M$_{odot}$ and $sim$3.6 M$_{odot}$ with an initial orbital period of $sim$5 days. Based on the fundamental parameters of the A-supergiant (luminosity $log$ L/L$_{odot} = 4.1pm$0.1 and effective temperature T$_{rm eff} = 8500pm$500 K) and evolutionary tracks of mass-transferring binaries, we found current masses of the gainer M$_{2} = 8.8pm$0.5 M$_{odot}$ and donor M$_{1} = 0.75pm0.25$ M$_{odot}$. We also modeled the objects IR-excess and derived a dust mass of $sim 5,times10^{-5}$ M$_{odot}$ in the optically-thin dusty disk. The orbital parameters and properties of the H$alpha$ line profile suggest that the circumstellar gaseous disk is predominantly circumbinary. The relatively low mass of the gainer led us to a suggestion that 3 Pup should be excluded from the B[e] supergiant group and moved to the FS CMa group. Overall these results further support our original suggestion that FS CMa objects are binary systems, where an earlier mass-transfer caused formation of the circumstellar envelope.
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