Article
Astronomy & Astrophysics
A. Frasca, H. M. J. Boffin, C. F. Manara, J. M. Alcala, P. Abraham, E. Covino, M. Fang, M. Gangi, G. J. Herczeg, A. Kospal, L. Venuti, F. M. Walter, J. Alonso-Santiago, K. Grankin, M. Siwak, E. Alecian, S. Cabrit
Summary: In this study, the close pre-main sequence spectroscopic binary CVSO 104 in Ori OB1 was analyzed, revealing the orbital elements and stellar parameters of the system, as well as a significant infrared excess related to a circumbinary disk. Both components were found to be accreting at a similar level, with excess emission observed in Hα and Hβ possibly connected to accretion structures. The optical companion CVSO 104 B was identified as a background Sun-like star not physically associated with the PMS system.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
T. Steindl, K. Zwintz, T. G. Barnes, M. Muellner, E. Vorobyov
Summary: The study aims to constrain the physics of accretion on protostellar seeds by using observed spectroscopic parameters and stellar pulsations. It discovered several previously unknown pulsating pre-main-sequence stars, with evolutionary tracks showing that a mass accretion rate of 5 x 10(-6) M-circle dot yr(-1) provides the best results.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
R. Carini, K. Biazzo, G. De Marchi, N. Panagia, G. Beccari, E. Brocato
Summary: In this study, the accretion properties of low-mass pre-main sequence stars in the LH 91 association within the Large Magellanic Clouds are investigated using optical multiband photometry obtained with the Hubble Space Telescope. The age distribution suggests a period of active star formation ranging from a few million years up to approximately 60 million years, with a gap between 5 million years and 10 million years. The masses of the pre-main sequence candidates range from 0.2 solar masses to 1.0 solar mass, with an average of approximately 0.80 solar mass. The results also show variations in accretion luminosity and mass accretion rate with the age of the stars. Comparison with LH 95 reveals that LH 91 appears to be in a more evolved stage. Additionally, the pre-main sequence candidates are found to be uniformly distributed without any evidence of clumps around more massive stars.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
T. Steindl, K. Zwintz, M. Muellner
Summary: This study investigates the asteroseismic modeling of pre-main-sequence delta Scuti stars and highlights the importance of including early stellar evolution physics in the calculations. The results show that insufficient input physics and imperfect modeling approaches lead to underestimated uncertainties and systematic errors in the extracted stellar parameters. A comparison between different modeling approaches suggests that a six-dimensional model with fixed accretion parameters is preferred over the previous ten-dimensional model. The modeling approach presented in this study can provide narrow constraints on the stellar parameters and has the potential to be applied in future research.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Jacob Cleaver, Lee Hartmann, Jaehan Bae
Summary: We investigate the role of the magnetorotational instability (MRI) in explaining the diverse range of observed accretion outbursts in protoplanetary discs. Our results suggest that short-lived, low accretion rate events are likely triggered in the inner disc and cannot be explained by MRI triggering through gravitational instability. By using time-dependent accretion disc models and comparing with observations, we find that the lag time between infrared and optical bursts in Gaia 17bpi can be explained by an outside-in propagation with an α > 0.1 in the MRI-active region. Our findings highlight the importance of near-infrared monitoring and call for more sophisticated simulations to better understand the observed phenomena.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Teresa A. M. Braun, Hsi-Wei Yen, Patrick M. Koch, Carlo F. Manara, Anna Miotello, Leonardo Testi
Summary: Analyzing archival molecular line data of PMS stars in Lupus and Taurus star-forming regions, researchers found that Feiden's magnetic model provides the best estimate for stellar masses in a certain mass range, showing the mass dependence of the accuracy of stellar evolutionary models.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
F. Backs, J. Poorta, Ch. Rab, A. R. Derkink, A. de Koter, L. Kaper, M. C. Ramirez-Tannus, I. Kamp
Summary: This study investigates the physical properties of the inner regions of the circumstellar disks of two young stellar objects. The results show the presence of hot gaseous inner disks and the possibility of cold outer gas and dust. The structures of these disks suggest that they might be undergoing clearing processes through boundary-layer accretion, photo-evaporation, or companion activity.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
N. T. Kurtovic, P. Pinilla, F. Long, M. Benisty, C. F. Manara, A. Natta, I Pascucci, L. Ricci, A. Scholz, L. Testi
Summary: The discovery of giant planets orbiting very low mass stars (VLMS) and observed substructures in disks around VLMS challenge existing planet formation models. Observations show the presence of cavities, rings, and gaps in disks around VLMS, providing insights into radial drift. Additionally, the comparison of gas and dust emission in these disks reveals valuable information about radial extent and structural formation.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Paola Pinilla, Antonio Garufi, Matias Garate
Summary: The frequency of giant planets may decrease for intermediate-mass stars, and the mechanism behind this phenomenon remains unclear. Through theoretical analysis, it is found that the radial drift velocity of dust particles sharply increases after 1-2 million years around intermediate-mass stars, potentially hindering planet formation. This high radial drift could explain the lack of disk detections around older intermediate-mass stars. Future high-resolution images can help us understand why planets around intermediate-mass stars are rare.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Lynne A. Hillenbrand, Kishalay De, Matthew Hankins, Mansi M. Kasliwal, Luisa M. Rebull, Ryan M. Lau, Roc M. Cutri, Michael C. B. Ashley, Viraj R. Karambelkar, Anna M. Moore, T. Travouillon, A. K. Mainzer
Summary: We report the discovery of a likely outbursting Class I young stellar object associated with the star-forming region NGC 281-W. The source is currently seen only at infrared wavelengths, and recent observations reveal a new, extended scattered light nebula.
ASTRONOMICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
J. Poorta, M. C. Ramirez-Tannus, A. de Koter, F. Backs, A. Derkink, A. Bik, L. Kaper
Summary: This study aims to constrain the physical properties of the inner parts of the circumstellar disks of massive young stellar objects B243 and B331. The results show that B243 features a hot gaseous inner disk with an inner radius of approximately 3 AU and an outer radius of around 6.5 AU. B331 also has a hot gaseous inner disk, with a gap separating it from a colder dusty outer disk starting at up to approximately 100 AU.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
S. K. Betti, K. Follette, S. Jorquera, G. Duchene, J. Mazoyer, M. Bonnefoy, G. Chauvin, L. M. Perez, A. Boccaletti, C. Pinte, A. J. Weinberger, C. Grady, L. M. Close, D. Defrere, E. C. Downey, P. M. Hinz, F. Menard, G. Schneider, A. J. Skemer, A. Vaz
Summary: The study utilized the LMIRCam imagery from the Large Binocular Telescope to explore the disk around the suspected Herbig Ae/Be star AB Aurigae, revealing morphological differences between different bands that could be related to the presence of icy grains. The analysis suggests that the scattering surfaces at different wavelengths are not colocated, leading to varying optical depth effects and indicating potential differences in grain population at different depths of the disk surface.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
D. Dmitriev, T. A. Ermolaeva, V. P. Grinin, I. S. Potravnov
Summary: During the burst of accretion activity observed in 2013, the accretion rate of RZ Psc increased significantly, indicating the instability of the accretion process during late stages of pre-main sequence evolution. By studying the magnetospheric emission in the H alpha line, we calculated the parameters of the magnetosphere and considered the recombination delay effect during gas motion in the stellar magnetosphere. The absence of magnetospheric absorption in the D Na I resonance lines allowed us to estimate a lower limit on the magnetosphere temperature and improve the precision of the accretion rate estimate. The best-fitting model suggests a logarithm of accretion rate of logM≈-10.1 +/- 0.3 (≈7x10-11 M⊙yr-1) and an inclination angle of RZ Psc of 43 degrees +/- 3 degrees, which is lower than the typical inclination angle for UX Ori stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
J. Erkal, C. F. Manara, P. C. Schneider, M. Vincenzi, B. Nisini, D. Coffey, J. M. Alcala, D. Fedele, S. Antoniucci
Summary: The study used the He I λ0830 angstrom line to probe the material in the inner regions of protostellar disks in young stars from Lupus and Upper Scorpius, finding variations in profile types and line properties, indicating changes in accretion and outflow signatures over time and with source properties.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Timmy N. N. Delage, Matias Garate, Satoshi Okuzumi, Chao-Chin Yang, Paola Pinilla, Mario Flock, Sebastian Markus Stammler, Tilman Birnstiel
Summary: This study aims to investigate the influence of dust evolution on magnetorotational instability (MRI) activity in protoplanetary disks. The results show that dust coagulation and settling lead to an increase in gas ionization degree and enhance MRI activity, while fragmentation has the opposite effect. Dust evolution alone does not completely reactivate the dead zone. For typical T-Tauri stars, the outer edge of the dead zone is expected to be located between 10 au and 50 au during the disk lifetime. The MRI activity evolution is also sensitive to the choice of minimum grain size in the dust distribution.
ASTRONOMY & ASTROPHYSICS
(2023)