The {\gamma} Dor stars as revealed by Kepler : A key to reveal deep-layer rotation in A and F stars

The {\gamma} Dor pulsating stars present high-order gravity modes, which make them important targets in the intermediate-and low-mass main-sequence region of the Hertzsprung-Russell diagram. Whilst we have only access to rotation in the envelope of the Sun, the g modes of {\gamma} Dor stars can in principle deliver us constraints on the inner layers. With the puzzling discovery of unexpectedly low rotation rates in the core of red giants, the {\gamma} Dor stars appear now as unique targets to explore internal angular momentum transport in the progenitors of red giants. Yet, the {\gamma} Dor pulsations remain hard to detect from the ground for their periods are close to 1 day. While the CoRoT space mission first revealed intriguing frequency spectra, the almost uninterrupted 4-year photometry from the Kepler mission eventually shed a new light on them. It revealed regularities in the spectra, expected to bear signature of physical processes, including rotation, in the shear layers close to the convective core. We present here the first results of our effort to derive exploitable seismic diagnosis for mid- to fast rotators among {\gamma} Dor stars. We confirm their potential to explore the rotation history of this early phase of stellar evolution.Comment: 4 pages, 1 figure, proceedings of the 22nd Los Alamos Stellar Pulsation Conference, "Wide-field variability surveys: a 21st-century perspective" held in San Pedro de Atacama, Chile, Nov. 28-Dec. 2, 201

TESS unveils the phase curve of WASP-33b. Characterization of the planetary atmosphere and the pulsations from the star

We present the detection and characterization of the full-orbit phase curve and secondary eclipse of the ultra-hot Jupiter WASP-33b at optical wavelengths, along with the pulsation spectrum of the host star. We analyzed data collected by the Transiting Exoplanet Survey Satellite (TESS) in sector 18. WASP-33b belongs to a very short list of highly irradiated exoplanets that were discovered from the ground and were later visited by TESS. The host star of WASP-33b is of delta Scuti-type and shows nonradial pulsations in the millimagnitude regime, with periods comparable to the period of the primary transit. These completely deform the photometric light curve, which hinders our interpretations. By carrying out a detailed determination of the pulsation spectrum of the host star, we find 29 pulsation frequencies with a signal-to-noise ratio higher than 4. After cleaning the light curve from the stellar pulsations, we confidently report a secondary eclipse depth of 305.8 +/- 35.5 parts-per-million (ppm), along with an amplitude of the phase curve of 100.4 +/- 13.1 ppm and a corresponding westward offset between the region of maximum brightness and the substellar point of 28.7 +/- 7.1 degrees, making WASP-33b one of the few planets with such an offset found so far. Our derived Bond albedo, A_B = 0.369 +/- 0.050, and heat recirculation efficiency, epsilon = 0.189 +/- 0.014, confirm again that he behavior of WASP-33b is similar to that of other hot Jupiters, despite the high irradiation received from its host star. By connecting the amplitude of the phase curve to the primary transit and depths of the secondary eclipse, we determine that the day- and nightside brightness temperatures of WASP-33b are 3014 +/- 60 K and 1605 +/- 45 K, respectively. From the detection of photometric variations due to gravitational interactions, we estimate a planet mass of M_P = 2.81 +/- 0.53 M$_J.Comment: 19 pages, 15 figure

The retroperitoneal sarcomas – the experience of single centre

Catedra de Oncologie, Universitatea de Stat de Medicină și Farmacie ”Nicolae Testemițanu”, IMSP Institutul Oncologic, Chișinău, Republica Moldova, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Sarcoamele retroperitoneale (SRP) constituie un grup heterogenic de tumori maligne. Criteriile comune ale acestor tumori sunt: regiunea anatomică în care se dezvoltă; proveniența mezenchimală; clinică silențioasă; rata înaltă a recurenței. RPS constituie 1/3 dintre toate tumorile retroperitoneumului și constituie aproximativ 15% dintre toate sarcoamele țesuturilor moi. Succesul tratamentului constă în diagnosticul precoce și radicalitatea actului chirurgical. Material și metode: lotul de studiu a fost constituit din 217 pacienți ai serviciului Gastrologie a IMSP IO, Chișinău, între anii 2005- 2019. Materialul histologic a fost examinat de un expert morfopatolog, Rezultate: Pentru diagnostic au fost utilizate USG, CT, MRI și examinarea histologică a materialului histologic obținut prin biopsie sau înlăturarea tumorii în întregime. Din totalul de 217 pacienți cu TRP, în 82 cazuri (36 bărbați și 46 femei, vârsta medie constituind 54,52 ani) au fost determinate una din formele histologice de SRP ceea ce a constituit 37,20%. Formele histologice identificate: liposarcom -23 cazuri (28,04%), leiomiosarcom – 20 cazuri (24,39%), histiocitom fibros malign 16 cazuri (19,51%), fibrosarcom – 6 cazuri (7,31%), angiosarcom 4 cazuri (4,87%), hemangiopericitom - 3 cazuri (3,65%), sarcom nediferențiat - 10 cazuri (12,19%). Tratamentul chirurgical radiacal a fost posibil de efectuat în 70 cazuri (85,36%), într-un caz s-a efectuat intervenție chirurgicală citoreductivă (1,21%), și în 10 cazuri (12,19%) s-a efectuat laparotomie de diagnostic. Pentru asigurarea radicalității în 27 cazuri (32,92%) s-a efectuat excizia ”en bloc”: în 17 cazuri (24,28%) cu un organ, în 8 cazuri (9,75 %) – 2 organe și într-un caz (1,42%) – 3 organe. Cele mai sacrificate organe au fost: rinichi – 10 cazuri (14,28%), colon - 6 cazuri (8,57%), intestin subțire - 6 cazuri (8,57%), splină - 4 cazuri (4,87%), glanda suprarenală - 2 cazuri (2,85%), pancreas - 2 cazuri (2,43%), stomac - 1 caz (1,42%). Rata recurențelor a constituit 25,61%. Concluzii: Sarcoamele retroperitoneale constituie cea mai întânită entitate nozologică dintre TRP în corpul uman, se caracterizează prin heterogenitate morfologică și are un tablou clinic nespecific. Deseori, asigurarea radicalități tratamentului chirurgical este necesară sacrificarea unui organ adiacent ca rinichi, colon, intestin subțire, splină.Background: Retroperitoneal sarcomas (RPS) represent a heterogenic group of malignant tumors. The common criteria of this group are: the common anatomical base; the mesenchymal origin of the tumor; the silent clinical manifestation; the high frequency of recurrence. RPS constitutes one-third of the malignant tumors occurring in retroperitoneum and accounting for approximately 15% of the soft tissue sarcomas of the human body. The success of treatment depends on early diagnosis and radical surgery. Methods and materials: the study group consists of 217 patients with primitive retroperitoneal tumors (PRT), reviewed by an expert pathologist, during the period 2005-2019 from the Gastrology clinic of IMSP IO Chisinău. Results: For diagnostic purpose following investigations were applied: USG, CT, MRI and histological exam of biopsy specimen of removed tumor. From the group of 217 patients with PRT we identified one of the histological forms of sarcoma in 82 cases (37,20%; 36 men and 46 women, average age 54,52 years). Identified histological forms are: liposarcoma - 23 cases (28,04%), leiomyosarcoma – 20 cases (24,39%), malign fibrous histiocytoma - 16 cases (19,51%), fibrosarcoma – 6 cases (7,31%), angiosarcoma - 4 cases (4,87%), hemangiopericytoma - 3 cases (3,65%), unclassified sarcoma - 10 cases ( 12,19%). Radical surgical treatment was performed in 70 cases (85,36%), in one case was performed cytoreductive surgery (1,21%), and in 10 cases (12,19%) was performed laparotomy of evaluation. To ensure the radicality in 27 cases (32,92%) was performed excision ”en bloc”: in 17 cases (24,28%) one organ, 8 cases (9,75 %) – 2 organs and 1 case (1,42%) – 3 organs. Slaughtered organs were: kidney – 10 cases (14,28%), colon - 6 cases (8,57%), small intestine - 6 cases (8,57%), spleen - 4 cases (4,87%), adrenal gland - 2 cases (2,85%), pancreas - 2 case (2,43%), stomach - 1 case (1,42%). The rate of recidivism recorded is 25,61%. Conclusion: The retroperitoneal sarcoma is the most common primitive retroperitoneal tumor in human body, that is characterized by morphological heterogeneity and it has an unspecific clinical manifestation. Often to ensure the radicality of surgery, it is necessary to sacrifice some adjacent organs (kidney, colon, small intestine, spleen)

The role of turbulent pressure as a coherent pulsational driving mechanism: the case of the delta Scuti star HD 187547

HD 187547 was the first candidate that led to the suggestion that solar-like oscillations are present in delta Scuti stars. Longer observations, however, show that the modes interpreted as solar-like oscillations have either very long mode lifetimes, longer than 960 days, or are coherent. These results are incompatible with the nature of `pure' stochastic excitation as observed in solar-like stars. Nonetheless, one point is certain: the opacity mechanism alone cannot explain the oscillation spectrum of HD 187547. Here we present new theoretical investigations showing that convection dynamics can intrinsically excite coherent pulsations in the chemically peculiar delta Scuti star HD 187547. More precisely, it is the perturbations of the mean Reynold stresses (turbulent pressure) that drives the pulsations and the excitation takes place predominantly in the hydrogen ionization zone.Comment: 8 pages, 4 figures, accepted to Ap

44 Tau: Discrimination between MS and post-MS models

For the Delta Scuti star 44 Tau 13 independent frequencies have been detected in previous studies. This star is unusual among the Delta Scuti stars because of its very low v sin i value of 2 +/- 1 km/s, indicating that it is either an extremely slow rotator or seen pole-on. 44 Tau shows unusually high amplitudes for a typical nonradially pulsating Delta Scuti star and is believed to be a connecting link between the high-amplitude Delta Scuti stars (HADS) and the low-amplitude Delta Scuti stars. We performed an asteroseimic study to find the appropriate theoretical model for this star. The fact that the radial fundamental and first overtone frequencies have been identified allows for reducing the number of possible solutions significantly. Standard post-main sequence models with inefficient convection in the envelope seem to be preferable in comparison with various models on the main sequence. They fit both observed global parameters of 44 Tau and most of identified radial and nonradial frequencies.Comment: 2 pages, 1 figure, to appear in Communications in Asteroseismology, vol.150, 2007 (Proc. Vienna Workshop on the Future of Asteroseismology, held in Vienna, Sept. 20-22, 2006, eds. G. Handler and G. Houdek

Searching for solar-like oscillations in the delta Scuti star rho Puppis

Despite the shallow convective envelopes of delta Scuti pulsators, solar-like oscillations are theoretically predicted to be excited in those stars as well. To search for such stochastic oscillations we organised a spectroscopic multi-site campaign for the bright, metal-rich delta Sct star rho Puppis. We obtained a total of 2763 high-resolution spectra using four telescopes. We discuss the reduction and analysis with the iodine cell technique, developed for searching for low-amplitude radial velocity variations, in the presence of high-amplitude variability. Furthermore, we have determined the angular diameter of rho Puppis to be 1.68 \pm 0.03 mas, translating into a radius of 3.52 \pm 0.07Rsun. Using this value, the frequency of maximum power of possible solar-like oscillations, is expected at ~43 \pm 2 c/d (498 \pm 23 muHz). The dominant delta Scuti-type pulsation mode of rho Puppis is known to be the radial fundamental mode which allows us to determine the mean density of the star, and therefore an expected large frequency separation of 2.73 c/d (31.6 muHz). We conclude that 1) the radial velocity amplitudes of the delta Scuti pulsations are different for different spectral lines; 2) we can exclude solar-like oscillations to be present in rho Puppis with an amplitude per radial mode larger than 0.5 m/s.Comment: 14 pages, 12 figure, accepted for MNRA

Classical gravitational spin-spin interaction

I obtain an exact, axially symmetric, stationary solution of Einstein's equations for two massless spinning particles. The term representing the spin-spin interaction agrees with recently published approximate work. The spin-spin force appears to be proportional to the inverse fourth power of the coordinate distance between the particles.Comment: six pages, no figures, journal ref:accepted for Classical and Quantum Gravit