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WIYN Open Cluster Study: The Old Open Cluster, NGC 188, and a Re-evaluation of Lithium-Richness Among Red Giants
Qinghui Sun, Constantine P. Deliyannis, Bruce A. Twarog +3
We present WIYN/Hydra spectra of 34 red giant candidate members of NGC 188, which, together with WOCS and Gaia data yield 23 single members, 6 binary members, 4 single nonmembers,…
When Do Stars Go BOOM?
Harvey B. Richer, Roger E. Cohen, Matteo Correnti +10
The maximum mass of a star that can produce a white dwarf (WD) is an important astrophysical quantity. One of the best approaches to establishing this limit is to search for WDs in…
A Fresh Look at AGB stars in Galactic Open Clusters with Gaia: Impact on Stellar Models and the Initial-Final Mass Relation
Paola Marigo, Diego Bossini, Michele Trabucchi +7
Benefiting from the GAIA second and early third releases of photometric and astrometric data we examine the population of asymptotic giant branch (AGB) stars that appear in the fie…
Intermediate-Mass Stars Become Magnetic White Dwarfs
Ilaria Caiazzo, Jeremy Heyl, Harvey Richer +8
When a star exhausts its nuclear fuel, it either explodes as a supernova or more quiescently becomes a white dwarf, an object about half the mass of our Sun with a radius of about…
Carbon star formation as seen through the non-monotonic initial-final mass relation
Paola Marigo, Jeffrey D. Cummings, Jason Lee Curtis +13
The initial-final mass relation (IFMR) links the birth mass of a star to the mass of the compact remnant left at its death. While the relevance of the IFMR across astrophysics is u…
Double white dwarf merger products among high-mass white dwarfs
Sihao Cheng, Jeffrey D. Cummings, Brice Ménard +1
Double white dwarf (double-WD) binaries may merge within a Hubble time and produce high-mass WDs. Compared to other high-mass WDs, the double-WD merger products have higher velocit…
A Massive Magnetic Helium Atmosphere White Dwarf Binary in a Young Star Cluster
Harvey B. Richer, Ronan M. Kerr, Jeremy Heyl +4
We have searched the Gaia DR2 catalogue for previously unknown hot white dwarfs in the direction of young open star clusters. The aim of this experiment was to try and extend the i…
TESS reveals that the nearby Pisces-Eridanus stellar stream is only 120 Myr old
Jason Lee Curtis, Marcel A. Agüeros, Eric E. Mamajek +2
Pisces-Eridanus (Psc-Eri), a nearby ( 80-226 pc) stellar stream stretching across 120 degrees of the sky, was recently discovered with Gaia data. The stream wa…
A cooling anomaly of high-mass white dwarfs
Sihao Cheng, Jeffrey D. Cummings, Brice Ménard
Recently, the power of Gaia data has revealed an enhancement of high-mass white dwarfs (WDs) on the Hertzsprung--Russell diagram, called the Q branch. This branch is located at the…
A Novel Approach to Constrain Rotational Mixing & Convective-Core Overshoot in Stars Using the Initial-Final Mass Relation
Jeffrey D. Cummings, Jason S. Kalirai, Jieun Choi +3
The semi-empirical initial-final mass relation (IFMR) connects spectroscopically analyzed white dwarfs in star clusters to the initial masses of the stars that formed them. Most cu…
The White Dwarf Initial-Final Mass Relation for Progenitor Stars From 0.85 to 7.5 M
Jeffrey D. Cummings, Jason S. Kalirai, P. -E. Tremblay +2
We present the initial-final mass relation (IFMR) based on the self-consistent analysis of Sirius B and 79 white dwarfs from 13 star clusters. We have also acquired additional sign…
Improved Main Sequence Turnoff Ages of Young Open Clusters: Multicolor UBV Techniques & the Challenges of Rotation
Jeffrey D. Cummings, Jason S. Kalirai
Main sequence turnoff ages in young open clusters are complicated by turnoffs that are sparse, have high binarity fractions, can be affected by differential reddening, and typicall…
A Data Release 2 catalogue of white dwarfs and a comparison with SDSS
Nicola Pietro Gentile Fusillo, Pier-Emmanuel Tremblay, Boris T. Gänsicke +11
We present a catalogue of white dwarf candidates selected from the second data release of (DR2). We used a sample of spectroscopically confirmed white dwarfs from the Sloan…
Can magnetic fields suppress convection in the atmosphere of cool white dwarfs? A case study on WD2105-820
Nicola Pietro Gentile Fusillo, Pier-Emmanuel Tremblay, Stefan Jordan +3
Around 10% of white dwarfs exhibit global magnetic structures with fields ranging from 1 kG to hundreds of MG. Recently, the first radiation magnetohydrodynamics simulations of the…
Multiple Populations in NGC 1851: Abundance Variations and UV Photometric Synthesis in the Washington and HST/WFC3 Systems
Jeffrey D. Cummings, Douglas Geisler, Sandro Villanova
The analysis of multiple populations (MPs) in globular clusters, both spectroscopically and photometrically, is key in understanding their formation and evolution. The relatively n…
WIYN Open Cluster Study. LXXV. Testing the Metallicity Dependence of Stellar Lithium Depletion Using Hyades-Aged Clusters. 1. Hyades & Praesepe
Jeffrey D. Cummings, Constantine P. Deliyannis, Ryan M. Maderak +1
WIYN/Hydra spectroscopy (at R~15,000) of the moderately metal-rich Praesepe and Hyades open clusters was used to study their main sequence (MS) iron ([Fe/H]) and lithium (A(Li)) ab…
The Field White Dwarf Mass Distribution
P. -E. Tremblay, J. Cummings, J. S. Kalirai +3
We revisit the properties and astrophysical implications of the field white dwarf mass distribution in preparation of Gaia applications. Our study is based on the two samples with…
An Ultramassive 1.28 M White Dwarf in NGC 2099
Jeffrey D. Cummings, Jason S. Kalirai, P. -E. Tremblay +2
With the Keck I Low-Resolution Imaging Spectrometer we have observed nine white dwarf candidates in the very rich open cluster NGC 2099 (M37). The spectroscopy shows seven to be DA…
Two Massive White Dwarfs from NGC 2323 and the Initial-Final Mass Relation for Progenitors of 4 to 6.5 M
Jeffrey D. Cummings, Jason S. Kalirai, P. -E. Tremblay +1
We have observed a sample of 10 white dwarf candidates in the rich open cluster NGC 2323 (M50) with the Keck Low-Resolution Imaging Spectrometer. The spectroscopy shows eight to be…
Initial-Final Mass Relation for 3 to 4 M Progenitors of White Dwarfs from the Single Cluster NGC 2099
Jeffrey D. Cummings, Jason S. Kalirai, P. -E. Tremblay +1
We have expanded the sample of observed white dwarfs in the rich open cluster NGC 2099 (M37) with the Keck Low-Resolution Imaging Spectrometer. Of 20 white dwarf candidates, the sp…
White Dwarf Cosmochronology in the Solar Neighborhood
P. -E. Tremblay, J. S. Kalirai, D. R. Soderblom +2
The study of the stellar formation history in the solar neighborhood is a powerful technique to recover information about the early stages and evolution of the Milky Way. We presen…
Uncovering Multiple Populations with Washington Photometry: I. The Globular Cluster NGC 1851
Jeffrey D. Cummings, D. Geisler, S. Villanova +1
The analysis of multiple populations (MPs) in globular clusters (GCs) has become a forefront area of research in astronomy. Multiple red giant branches (RGBs), subgiant branches (S…
Lithium Abundances of the Super-Metal-Rich Open Cluster NGC 6253
Jeffrey D. Cummings, Constantine P. Deliyannis, Barbara Anthony-Twarog +2
High-resolution CTIO 4-m/HYDRA spectroscopy of the super-metal-rich open cluster NGC 6253 ([Fe/H]=+0.43+/-0.01) has been used to study the stellar lithium (Li) abundances near the…
Lithium in the Intermediate-Age Open Cluster, NGC 3680
B. J. Anthony-Twarog, C. P. Deliyannis, B. A. Twarog +2
High-dispersion spectra centered on the Li 6708 A line have been obtained for 70 potential members of the open cluster NGC 3680, with an emphasis on stars in the turnoff region. A…