256 citations · 489 across the 27 of their papers we have counts for
23 papers · 1 filter
ABYSS. IV. Identifying signatures of stellar youth in APOGEE spectra
Valentina Bonilla Villalobos, Marina Kounkel, Joseph Mullen +9
We develop a convolutional neural network classifier that performs spectroscopic identification of stellar youth (<40 Myr) in APOGEE spectra. This classifier is sensitive to severa…
On the degeneracy of solutions from stellar spectropolarimetric data
J. C. Ramirez Velez, J. M. Raygoza-Romero, I. H. Lopez-Nava +3
In this work we investigate the inversion accuracy of stellar magnetic fields through the analysis of spectropolarimetric data. We performed several noise free tests to untangle th…
A Probabilistic Framework for Population Studies of the Solar Neighborhood: Application to SDSS-V and Gaia
Ilija Medan, Keivan G. Stassun, Zachary Way +8
Studies of the Solar Neighborhood require spectroscopic follow-up of stars identified in astrometric surveys to fully characterize their physical properties. The SDSS-V Solar Neigh…
Stellar Parameters of BOSS M dwarfs in SDSS-V DR19
Dan Qiu, Jennifer A. Johnson, Chao Liu +15
We utilized the Stellar LAbel Machine (SLAM), a data-driven model based on Support Vector Regression, to derive stellar parameters ([Fe/H], , and ) for SDSS-V…
Atmospheric parameters and chemical abundances of young stars with APOGEE. I. Orion star-forming region
Ricardo López-Valdivia, Lucía Adame, Carlos G. Román-Zúñiga +19
We derive atmospheric parameters and chemical abundances in young G-, K-, and M-type stars (temperatures between 6500 and 3100 K) using infrared APOGEE-2 spectra. Atmospheric param…
Extreme Lithium Depletion in Solar Twins: Challenging Non-Standard Mixing Models
Isabelle Winnick, Jhon Yana Galarza, Henrique Reggiani +12
Lithium (Li) is a powerful tracer of stellar mixing, gradually depleted in solar twins by non-standard transport below the convective zone. Here, we identify six new solar twins wi…
ABYSS III: Observing accretion activity in young stars through empirical veiling measurements
Serat Saad, Marina Kounkel, Keivan G. Stassun +5
Stellar accretion plays an important role in the early stages of stellar evolution, particularly in Classical T Tauri Stars (CTTSs). Accretion of a CTTS can be related to different…
HIP 8522: A Puzzling Young Solar Twin with the Lowest Detected Lithium
Jhon Yana Galarza, Diego Lorenzo-Oliveira, Thiago Ferreira +8
We present HIP 8522, a young solar twin with the lowest detected lithium, potentially a field blue straggler or the result of episodic early accretion. Its stellar parameters ($T_{…
Atmospheric parameters and chemical abundances within 100 pc. A sample of G, K, and M main-sequence stars
Ricardo López-Valdivia, Lucía Adame, Eduardo Zagala Lagunas +9
To date, we have access to enormous inventories of stellar spectra that allow the extraction of atmospheric parameters and chemical abundances essential in stellar studies. However…
Rotational Evolution of Classical T Tauri Stars: Models and Observations
Javier Serna, Giovanni Pinzón, Jesús Hernández +17
We developed a grid of stellar rotation models for low-mass and solar-type Classical T Tauri stars (CTTS) (). These models incorporate the star-…
ABYSS II: Identification of young stars in optical SDSS spectra and their properties
Serat Saad, Kaitlyn Lane, Marina Kounkel +9
We developed a tool that measures equivalent widths of various lines in low resolution optical spectra, and it was applied to stellar spectra obtained as part of SDSS-V and LAMOST…
Effective Temperature Estimations from Line Depth Ratios in the \H\ and \K-band Spectra of IGRINS
Melike Afşar, Zeynep Bozkurt, Gamze Böcek Topcu +5
Determining accurate effective temperatures of stars buried in the dust-obscured Galactic regions is extremely difficult from photometry. Fortunately, high-resolution infrared spec…
The IGRINS YSO Survey III: Stellar parameters of pre-main sequence stars in Ophiuchus and Upper Scorpius
Ricardo López-Valdivia, Gregory N. Mace, Eunkyu Han +9
We used the Immersion GRating Infrared Spectrometer (IGRINS) to determine fundamental parameters for 61 K- and M-type young stellar objects (YSOs) located in the Ophiuchus and Uppe…
Pre-main Sequence Brackett Emitters in the APOGEE DR17 Catalog: Line Strengths and Physical Properties of Accretion Columns
Hunter Campbell, Elliott Khilfeh, Kevin R. Covey +21
Very young (t 10 Myrs) stars possess strong magnetic fields that channel ionized gas from the interiors of their circumstellar discs to the surface of the star. Upon imp…
Rocky planet engulfment in the binary system HIP 71726-37
J. Yana Galarza, R. López-Valdivia, J. Meléndez +1
Binary stars are supposed to be chemically homogeneous, as they are born from the same molecular cloud. However, high precision chemical abundances show that some binary systems di…
The IGRINS YSO Survey I. Stellar parameters of pre-main sequence stars in Taurus-Auriga
Ricardo López-Valdivia, Kimberly R. Sokal, Gregory N. Mace +19
We present fundamental parameters for 110 canonical K- & M-type (1.30.13) Taurus-Auriga young stellar objects (YSOs). The analysis produces a simultaneous determination…
Searching for new solar twins: The Inti survey for the Northern Sky
J. Y. Galarza, R. López-Valdivia, D. Lorenzo-Oliveira +9
Solar twins are key in different areas of astrophysics, however only just over a hundred were identified and well-studied in the last two decades. In this work, we take advantage o…
Projected Rotational Velocities and Fundamental Properties of Low-Mass Pre-Main Sequence Stars in the Taurus-Auriga Star Forming Region
Larissa A. Nofi, Christopher M. Johns-Krull, Ricardo López-Valdivia +11
The projected stellar rotational velocity () is critical for our understanding of processes related to the evolution of angular momentum in pre-main sequence stars. We pr…
Compact Disks in a High Resolution ALMA Survey of Dust Structures in the Taurus Molecular Cloud
Feng Long, Gregory J. Herczeg, Daniel Harsono +24
We present a high-resolution (, au, mean sensitivity of Jy~beam at 225 GHz) snapshot survey of 32 protoplanetary disks around young stars with spe…
Effective Temperatures of Low-Mass Stars from High-Resolution H-band Spectroscopy
Ricardo López-Valdivia, Gregory N. Mace, Kimberly R. Sokal +9
High-resolution, near-infrared spectra will be the primary tool for finding and characterizing Earth-like planets around low-mass stars. Yet, the properties of exoplanets can not b…
Mg, Al, Si, Ca, Ti, Fe, and Ni abundance for a sample of solar analogues
Ricardo López-Valdivia, Emanuele Bertone, Miguel Chávez
We report on the determination of chemical abundances of 38 solar analogues, including 11 objects previously identified as super metal-rich stars. We have measured the equivalent w…
Lithium abundance in a sample of solar-like stars
R. López-Valdivia, J. B. Hernández-Águila, E. Bertone +3
We report on the determination of the lithium abundance [A(Li)] of 52 solar-like stars. For 41 objects the A(Li) here presented corresponds to the first measurement. We have measur…
Supersolar metallicity in G0-G3 main sequence stars with V<15
R. López-Valdivia, E. Bertone, M. Chávez +4
The basic stellar atmospheric parameters (effective temperature, surface gravity and global metallicity) were simultaneously determined for a sample of 233 stars, limited in magnit…