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Articles 1 - 24 of 24
Full-Text Articles in Physical Sciences and Mathematics
Toi-1468: A System Of Two Transiting Planets, A Super-Earth And A Mini-Neptune, On Opposite Sides Of The Radius Valley, P. Chaturvedi, P. Bluhm, E. Nagel, A. P. Hatzes, G. Morello, M. Brady, J. Korth, K. Molaverdikhani, D. Kossakowski, J. A. Caballero, E. W. Guenther, E. Pallé, N. Espinoza, A. Seifahrt, N. Lodieu, C. Cifuentes, E. Furlan, P. J. Amado, T. Barclay, J. Bean, V. J. S. Béjar, G. Bergond, A. W. Boyle, D. Ciardi, K. A. Collins, K. I. Collins, E. Esparza-Borges, A. Fukui, C. L. Gnilka, R. Goeke, P. Guerra, T. Henning, E. Herrero, S. B. Howell, S. V. Jeffers, J. M. Jenkins, Eric L.N. Jensen, D. Kasper, T. Kodama, D. W. Latham, M. J. López-González, R. Luque, D. Montes, J. C. Morales, M. Mori, F. Murgas, N. Narita, G. Nowak, H. Parviainen, V. M. Passegger, A. Quirrenbach, S. Reffert, A. Reiners, I. Ribas, G. R. Ricker, E. Rodriguez, C. Rodríguez-López, M. Schlecker, R. P. Schwarz, A. Schweitzer, S. Seager, G. Stefánsson, C. Stockdale, L. Tal-Or, J. D. Twicken, S. Vanaverbeke, G. Wang, D. Watanabe, J. N. Winn, M. Zechmeister
Toi-1468: A System Of Two Transiting Planets, A Super-Earth And A Mini-Neptune, On Opposite Sides Of The Radius Valley, P. Chaturvedi, P. Bluhm, E. Nagel, A. P. Hatzes, G. Morello, M. Brady, J. Korth, K. Molaverdikhani, D. Kossakowski, J. A. Caballero, E. W. Guenther, E. Pallé, N. Espinoza, A. Seifahrt, N. Lodieu, C. Cifuentes, E. Furlan, P. J. Amado, T. Barclay, J. Bean, V. J. S. Béjar, G. Bergond, A. W. Boyle, D. Ciardi, K. A. Collins, K. I. Collins, E. Esparza-Borges, A. Fukui, C. L. Gnilka, R. Goeke, P. Guerra, T. Henning, E. Herrero, S. B. Howell, S. V. Jeffers, J. M. Jenkins, Eric L.N. Jensen, D. Kasper, T. Kodama, D. W. Latham, M. J. López-González, R. Luque, D. Montes, J. C. Morales, M. Mori, F. Murgas, N. Narita, G. Nowak, H. Parviainen, V. M. Passegger, A. Quirrenbach, S. Reffert, A. Reiners, I. Ribas, G. R. Ricker, E. Rodriguez, C. Rodríguez-López, M. Schlecker, R. P. Schwarz, A. Schweitzer, S. Seager, G. Stefánsson, C. Stockdale, L. Tal-Or, J. D. Twicken, S. Vanaverbeke, G. Wang, D. Watanabe, J. N. Winn, M. Zechmeister
Physics & Astronomy Faculty Works
We report the discovery and characterization of two small transiting planets orbiting the bright M3.0V star TOI-1468 (LSPM J0106+1913), whose transit signals were detected in the photometric time series in three sectors of the TESS mission. We confirm the planetary nature of both of them using precise radial velocity measurements from the CARMENES and MAROON-X spectrographs, and supplement them with ground-based transit photometry. A joint analysis of all these data reveals that the shorter-period planet, TOI-1468 b (Pb = 1.88 d), has a planetary mass of Mb = 3.21 ± 0.24 M⊕ and a radius of …
An Ultra-Short-Period Transiting Super-Earth Orbiting The M3 Dwarf Toi-1685, P. Bluhm, E. Pallé, K. Molaverdikhani, J. Kemmer, A. P. Hatzes, D. Kossakowski, S. Stock, J. A. Caballero, J. Lillo-Box, V. J. S. Béjar, M. G. Soto, P. J. Amado, P. Brown, C. Cadieux, R. Cloutier, K. A. Collins, K. I. Collins, M. Cortés-Contreras, R. Doyon, S. Dreizler, N. Espinoza, A. Fukui, E. González-Álvarez, T. Henning, K. Horne, S. V. Jeffers, J. M. Jenkins, Eric L.N. Jensen, A. Kaminski, J. F. Kielkopf, N. Kusakabe, M. Kürster, D. Lafrenière, R. Luque, F. Murgas, D. Montes, J. C. Morales, N. Narita, V. M. Passegger, A. Quirrenbach, P. Schöfer, S. Reffert, A. Reiners, I. Ribas, G. R. Ricker, S. Seager, A. Schweitzer, R. P. Schwarz, M. Tamura, T. Trifonov, R. Vanderspek, J. Winn, M. Zechmeister, M. R. Zapatero Osorio
An Ultra-Short-Period Transiting Super-Earth Orbiting The M3 Dwarf Toi-1685, P. Bluhm, E. Pallé, K. Molaverdikhani, J. Kemmer, A. P. Hatzes, D. Kossakowski, S. Stock, J. A. Caballero, J. Lillo-Box, V. J. S. Béjar, M. G. Soto, P. J. Amado, P. Brown, C. Cadieux, R. Cloutier, K. A. Collins, K. I. Collins, M. Cortés-Contreras, R. Doyon, S. Dreizler, N. Espinoza, A. Fukui, E. González-Álvarez, T. Henning, K. Horne, S. V. Jeffers, J. M. Jenkins, Eric L.N. Jensen, A. Kaminski, J. F. Kielkopf, N. Kusakabe, M. Kürster, D. Lafrenière, R. Luque, F. Murgas, D. Montes, J. C. Morales, N. Narita, V. M. Passegger, A. Quirrenbach, P. Schöfer, S. Reffert, A. Reiners, I. Ribas, G. R. Ricker, S. Seager, A. Schweitzer, R. P. Schwarz, M. Tamura, T. Trifonov, R. Vanderspek, J. Winn, M. Zechmeister, M. R. Zapatero Osorio
Physics & Astronomy Faculty Works
Dynamical histories of planetary systems, as well as the atmospheric evolution of highly irradiated planets, can be studied by characterizing the ultra-short-period planet population, which the TESS mission is particularly well suited to discover. Here, we report on the follow-up of a transit signal detected in the TESS sector 19 photometric time series of the M3.0 V star TOI-1685 (2MASS J04342248+4302148). We confirm the planetary nature of the transit signal, which has a period of Pb = 0.6691403−0.0000021+0.0000023 d, using precise radial velocity measurements taken with the CARMENES spectrograph. From the joint photometry and radial velocity analysis, we estimate the …
The Carmenes Search For Exoplanets Around M Dwarfs: Lp 714-47 B (Toi 442.01): Populating The Neptune Desert, S. Dreizler, I. J. M. Crossfield, D. Kossakowski, P. Plavchan, S. V. Jeffers, J. Kemmer, R. Luque, N. Espinoza, E. Pallé, K. Stassun, E. Matthews, B. Cale, J. A. Caballero, M. Schlecker, J. Lillo-Box, M. Zechmeister, S. Lalitha, A. Reiners, A. Soubkiou, B. Bitsch, M. R. Zapatero Osorio, P. Chaturvedi, A. P. Hatzes, G. Ricker, R. Vaderspek, D. W. Latham, S. Seager, J. Winn, J. M. Jenkins, J. Aceituno, P. J. Amado, K. Barkaoui, M. Barbieri, N. M. Batalha, F. F. Bauer, B. Benneke, Z. Benkhaldoun, C. Beichman, J. Berberian, J. Burt, R. P. Butler, D. A. Caldwell, A. Chintada, A. Chontos, J. L. Christiansen, D. R. Ciardi, C. Cifuentes, K. A. Collins, K. I. Collins, D. Combs, M. Cortés-Contreras, J. D. Crane, T. Daylan, D. Dragomir, E. Esparza-Borges, P. Evans, F. Feng, E. E. Flowers, A. Fukui, B. Fulton, E. Furlan, E. Gaidos, C. Geneser, S. Giacalone, M. Gillon, E. Gonzales, V. Gorjian, C. Hellier, D. Hidalgo, A. W. Howard, S. Howell, D. Huber, H. Isaacson, E. Jehin, Eric L.N. Jensen, A. Kaminski, S. R. Kane, K. Kawauchi, J. F. Kielkopf, H. Klahr, M. R. Kosiarek, L. Kreidberg, M. Kürster, M. Lafarga, J. Livingston, D. Louie, A. Mann, A. Madrigal-Aguado, R. A. Matson, T. Mocnik, J. C. Morales, P. S. Muirhead, F. Murgas, S. Nandakumar, N. Narita, G. Nowak, M. Oshagh, P. Parviainen, V. M. Passegger, D. Pollacco, F. J. Pozuelos, A. Quirrenbach, M. Reefe, I. Ribas, P. Robertson, C. Rodríguez-López, M. E. Rose, A. Roy, A. Schweitzer, J. Schlieder, S. Shectman, A. Tanner, H. V. Şenavci, J. Teske, J. D. Twicken, J. Villasenor, S. X. Wang, L. M. Weiss, J. Wittrock, M. Yilmaz, F. Zohrabi
The Carmenes Search For Exoplanets Around M Dwarfs: Lp 714-47 B (Toi 442.01): Populating The Neptune Desert, S. Dreizler, I. J. M. Crossfield, D. Kossakowski, P. Plavchan, S. V. Jeffers, J. Kemmer, R. Luque, N. Espinoza, E. Pallé, K. Stassun, E. Matthews, B. Cale, J. A. Caballero, M. Schlecker, J. Lillo-Box, M. Zechmeister, S. Lalitha, A. Reiners, A. Soubkiou, B. Bitsch, M. R. Zapatero Osorio, P. Chaturvedi, A. P. Hatzes, G. Ricker, R. Vaderspek, D. W. Latham, S. Seager, J. Winn, J. M. Jenkins, J. Aceituno, P. J. Amado, K. Barkaoui, M. Barbieri, N. M. Batalha, F. F. Bauer, B. Benneke, Z. Benkhaldoun, C. Beichman, J. Berberian, J. Burt, R. P. Butler, D. A. Caldwell, A. Chintada, A. Chontos, J. L. Christiansen, D. R. Ciardi, C. Cifuentes, K. A. Collins, K. I. Collins, D. Combs, M. Cortés-Contreras, J. D. Crane, T. Daylan, D. Dragomir, E. Esparza-Borges, P. Evans, F. Feng, E. E. Flowers, A. Fukui, B. Fulton, E. Furlan, E. Gaidos, C. Geneser, S. Giacalone, M. Gillon, E. Gonzales, V. Gorjian, C. Hellier, D. Hidalgo, A. W. Howard, S. Howell, D. Huber, H. Isaacson, E. Jehin, Eric L.N. Jensen, A. Kaminski, S. R. Kane, K. Kawauchi, J. F. Kielkopf, H. Klahr, M. R. Kosiarek, L. Kreidberg, M. Kürster, M. Lafarga, J. Livingston, D. Louie, A. Mann, A. Madrigal-Aguado, R. A. Matson, T. Mocnik, J. C. Morales, P. S. Muirhead, F. Murgas, S. Nandakumar, N. Narita, G. Nowak, M. Oshagh, P. Parviainen, V. M. Passegger, D. Pollacco, F. J. Pozuelos, A. Quirrenbach, M. Reefe, I. Ribas, P. Robertson, C. Rodríguez-López, M. E. Rose, A. Roy, A. Schweitzer, J. Schlieder, S. Shectman, A. Tanner, H. V. Şenavci, J. Teske, J. D. Twicken, J. Villasenor, S. X. Wang, L. M. Weiss, J. Wittrock, M. Yilmaz, F. Zohrabi
Physics & Astronomy Faculty Works
We report the discovery of a Neptune-like planet (LP 714-47 b, P = 4.05204 d, mb = 30.8 ± 1.5M⊕, Rb = 4.7 ± 0.3 R⊕) located in the “hot Neptune desert”. Confirmation of the TESS Object of Interest (TOI 442.01) was achieved with radial-velocity follow-up using CARMENES, ESPRESSO, HIRES, iSHELL, and PFS, as well as from photometric data using TESS, Spitzer, and ground-based photometry from MuSCAT2, TRAPPIST-South, MONET-South, the George Mason University telescope, the Las Cumbres Observatory Global Telescope network, the El Sauce telescope, the TÜBİTAK National Observatory, the University of Louisville Manner Telescope, and WASP-South. We also present …
Precise Mass And Radius Of A Transiting Super-Earth Planet Orbiting The M Dwarf Toi-1235: A Planet In The Radius Gap?, P. Bluhm, R. Luque, N. Espinoza, E. Pallé, J. A. Caballero, S. Dreizler, J. H. Livingston, S. Mathur, A. Quirrenbach, S. Stock, V. Van Eylen, G. Nowak, E. D. López, S. Csizmadia, M. R. Zapatero Osorio, P. Schöfer, J. Lillo-Box, M. Oshagh, E. González-Álvarez, P. J. Amado, D. Barrado, V. J. S. Béjar, B. Cale, P. Chaturvedi, M. El Mufti, A. Ercolino, M. Fridlund, E. Gaidos, R. A. García, I. Georgieva, L. González-Cuesta, P. Guerra, A. P. Hatzes, T. Henning, E. Herrero, D. Hidalgo, G. Isopi, S. V. Jeffers, J. M. Jenkins, Eric L.N. Jensen, P. Kábath, A. Kaminski, J. Kemmer, J. Korth, D. Kossakowski, M. Kürster, M. Lafarga, F. Mallia, D. Montes, J. C. Morales, M. Morales-Calderón, F Murgas, N. Narita, V. M. Passegger, S. Pedraz, C. M. Persson, P. Plavchan, H. Rauer, S. Redfield, S. Reffert, A. Reiners, I. Ribas, G. R. Ricker, C. Rodríguez-López, A. R. G. Santos, S. Seager, M. Schlecker, A. Schweitzer, Y. Shan, M. G. Soto, J. Subjak, L. Tal-Or, T. Trifonov, S. Vanaverbeke, R. Vanderspek, J. Wittrock, M. Zechmeister, F. Zohrabi
Precise Mass And Radius Of A Transiting Super-Earth Planet Orbiting The M Dwarf Toi-1235: A Planet In The Radius Gap?, P. Bluhm, R. Luque, N. Espinoza, E. Pallé, J. A. Caballero, S. Dreizler, J. H. Livingston, S. Mathur, A. Quirrenbach, S. Stock, V. Van Eylen, G. Nowak, E. D. López, S. Csizmadia, M. R. Zapatero Osorio, P. Schöfer, J. Lillo-Box, M. Oshagh, E. González-Álvarez, P. J. Amado, D. Barrado, V. J. S. Béjar, B. Cale, P. Chaturvedi, M. El Mufti, A. Ercolino, M. Fridlund, E. Gaidos, R. A. García, I. Georgieva, L. González-Cuesta, P. Guerra, A. P. Hatzes, T. Henning, E. Herrero, D. Hidalgo, G. Isopi, S. V. Jeffers, J. M. Jenkins, Eric L.N. Jensen, P. Kábath, A. Kaminski, J. Kemmer, J. Korth, D. Kossakowski, M. Kürster, M. Lafarga, F. Mallia, D. Montes, J. C. Morales, M. Morales-Calderón, F Murgas, N. Narita, V. M. Passegger, S. Pedraz, C. M. Persson, P. Plavchan, H. Rauer, S. Redfield, S. Reffert, A. Reiners, I. Ribas, G. R. Ricker, C. Rodríguez-López, A. R. G. Santos, S. Seager, M. Schlecker, A. Schweitzer, Y. Shan, M. G. Soto, J. Subjak, L. Tal-Or, T. Trifonov, S. Vanaverbeke, R. Vanderspek, J. Wittrock, M. Zechmeister, F. Zohrabi
Physics & Astronomy Faculty Works
We report the confirmation of a transiting planet around the bright weakly active M0.5 V star TOI-1235 (TYC 4384–1735–1, V ≈ 11.5 mag), whose transit signal was detected in the photometric time series of sectors 14, 20, and 21 of the TESS space mission. We confirm the planetary nature of the transit signal, which has a period of 3.44 d, by using precise RV measurements with the CARMENES, HARPS-N, and iSHELL spectrographs, supplemented by high-resolution imaging and ground-based photometry. A comparison of the properties derived for TOI-1235 b with theoretical models reveals that the planet has a rocky composition, with …
The Strange Evolution Of The Large Magellanic Cloud Cepheid Ogle-Lmc-Cep1812, Hilding R. Neilson, Robert G. Izzard, Nobert Langer, Richard Ignace
The Strange Evolution Of The Large Magellanic Cloud Cepheid Ogle-Lmc-Cep1812, Hilding R. Neilson, Robert G. Izzard, Nobert Langer, Richard Ignace
Richard Ignace
Classical Cepheids are key probes of both stellar astrophysics and cosmology as standard candles and pulsating variable stars. It is important to understand Cepheids in unprecedented detail in preparation for upcoming Gaia, James Webb Space Telescope (JWST) and extremely-large telescope observations. Cepheid eclipsing binary stars are ideal tools for achieving this goal, however there are currently only three known systems. One of those systems, OGLE-LMC-CEP1812, raises new questions about the evolution of classical Cepheids because of an apparent age discrepancy between the Cepheid and its red giant companion. We show that the Cepheid component is actually the product of a …
Spectrophotometrically Identified Stars In The Pears-N And Pears-S Fields., N. Pirzkal, A. J. Burgasser, S. Malhotra, Benne W. Holwerda, K. C. Sahu, J. E. Rhoads, C. Xu, J. J. Bochanski, J. R. Walsh, R. A. Windhorst, N. P. Hathi, S. H. Cohen
Spectrophotometrically Identified Stars In The Pears-N And Pears-S Fields., N. Pirzkal, A. J. Burgasser, S. Malhotra, Benne W. Holwerda, K. C. Sahu, J. E. Rhoads, C. Xu, J. J. Bochanski, J. R. Walsh, R. A. Windhorst, N. P. Hathi, S. H. Cohen
Benne Holwerda
Deep ACS slitless grism observations and identification of stellar sources are presented within the Great Observatories Origins Deep Survey North and South fields which were obtained in the Probing Evolution And Reionization Spectroscopically (PEARS) program. It is demonstrated that even low-resolution spectra can be a very powerful means of identifying stars in the field, especially low-mass stars with stellar types M0 and later. The PEARS fields lay within the larger GOODS fields, and we used new, deeper images to further refine the selection of stars in the PEARS field, down to a magnitude of z850 = 25 using a newly …
How Hospitable Are Space Weather Affected Habitable Zones? The Role Of Ion Escape, Vladimir S. Airapetian, Alex Glocer, George V. Khazanov, Robert O Parke Loyd, Kevin France, Jan Josef Sojka, William C. Danchi, Michael W. Liemohn
How Hospitable Are Space Weather Affected Habitable Zones? The Role Of Ion Escape, Vladimir S. Airapetian, Alex Glocer, George V. Khazanov, Robert O Parke Loyd, Kevin France, Jan Josef Sojka, William C. Danchi, Michael W. Liemohn
All Physics Faculty Publications
Atmospheres of exoplanets in the habitable zones around active young G-K-M stars are subject to extreme X-ray and EUV (XUV) fluxes from their host stars that can initiate atmospheric erosion. Atmospheric loss affects exoplanetary habitability in terms of surface water inventory, atmospheric pressure, the efficiency of greenhouse warming, and the dosage of the UV surface irradiation. Thermal escape models suggest that exoplanetary atmospheres around active K-M stars should undergo massive hydrogen escape, while heavier species including oxygen will accumulate forming an oxidizing atmosphere. Here, we show that non-thermal oxygen ion escape could be as important as thermal, hydrodynamic H escape …
The Strange Evolution Of The Large Magellanic Cloud Cepheid Ogle-Lmc-Cep1812, Hilding R. Neilson, Robert G. Izzard, Nobert Langer, Richard Ignace
The Strange Evolution Of The Large Magellanic Cloud Cepheid Ogle-Lmc-Cep1812, Hilding R. Neilson, Robert G. Izzard, Nobert Langer, Richard Ignace
ETSU Faculty Works
Classical Cepheids are key probes of both stellar astrophysics and cosmology as standard candles and pulsating variable stars. It is important to understand Cepheids in unprecedented detail in preparation for upcoming Gaia, James Webb Space Telescope (JWST) and extremely-large telescope observations. Cepheid eclipsing binary stars are ideal tools for achieving this goal, however there are currently only three known systems. One of those systems, OGLE-LMC-CEP1812, raises new questions about the evolution of classical Cepheids because of an apparent age discrepancy between the Cepheid and its red giant companion. We show that the Cepheid component is actually the product of a …
Boss Ultracool Dwarfs I: Colors And Magnetic Activity Of M And L Dwarfs, Sarah J. Schmidt, Suzanne L. Hawley, Andrew A. West, John J. Bochanski, James R. A. Davenport, Jian Ge, Doanld P. Schneider
Boss Ultracool Dwarfs I: Colors And Magnetic Activity Of M And L Dwarfs, Sarah J. Schmidt, Suzanne L. Hawley, Andrew A. West, John J. Bochanski, James R. A. Davenport, Jian Ge, Doanld P. Schneider
Physics & Astronomy
We present the colors and activity of ultracool (M7–L8) dwarfs from the Tenth Data Release of the Sloan Digital Sky Survey (SDSS). We combine previous samples of SDSS M and L dwarfs with new data obtained from the Baryon Oscillation Sky Survey (BOSS) to produce the BOSS Ultracool Dwarf (BUD) sample of 11820 M7–L8 dwarfs. By combining SDSS data with photometry from 2MASS and the Wide-field Infrared Sky Explorer (WISE) mission, we present ultracool dwarf colors from to as a function of spectral type, and extend the SDSS–2MASS–WISE color locus to include ultracool dwarfs. The , , …
Possible Identification Of A Metal-Rich Old Moving Group: High-Resolution Spectroscopy Of Candidate Members, Abigail R. Daane, Jeremy R. King, Simon C. Schuler
Possible Identification Of A Metal-Rich Old Moving Group: High-Resolution Spectroscopy Of Candidate Members, Abigail R. Daane, Jeremy R. King, Simon C. Schuler
Jeremy R King
Using new high-resolution spectroscopic observations from both the McDonald Observatory 2.7 m and Kitt Peak National Observatory 4 m telescopes, we observed four candidate members of the Ursa Major moving group previously suggested to instead belong to a significantly older kinematic assemblage. The Fe abundances we measure strongly suggest that these stars are not UMa members but form a more metal-rich group of stars (+0.10 ≤ [Fe/H] ≤ +0.18) with an age near 3 Gyr. Our [Ca/H] determinations corroborate this result. The apparent similarities in metallicity and previously discovered UVW space motions lend credence to prior suggestions that these stars …
Spectroscopic Abundances And Membership In The Wolf 630 Moving Group, Eric J. Bubar, Jeremy R. King
Spectroscopic Abundances And Membership In The Wolf 630 Moving Group, Eric J. Bubar, Jeremy R. King
Jeremy R King
The concept of kinematic assemblages evolving from dispersed stellar clusters has remained contentious since Eggen’s initial formulation of moving groups in the 1960s. With high-quality parallaxes from the Hipparcos space astrometry mission, distance measurements for thousands of nearby, seemingly isolated stars are currently available. With these distances, a high-resolution spectroscopic abundance analysis can be brought to bear on the alleged members of these moving groups. If a structure is a relic of an open cluster, the members can be expected to be monolithic in age and abundance in as much as homogeneity is observed in young open clusters. In this …
Lithium In The Upper Centaurus Lupus And Lower Centaurus Crux Subgroups Of Scorpius-Centaurus, Eric J. Bubar, Marc Schaeuble, Jeremy R. King, Eric E. Mamajek, John R. Stauffer
Lithium In The Upper Centaurus Lupus And Lower Centaurus Crux Subgroups Of Scorpius-Centaurus, Eric J. Bubar, Marc Schaeuble, Jeremy R. King, Eric E. Mamajek, John R. Stauffer
Jeremy R King
We utilize spectroscopically derived model atmosphere parameters and the Li i λ6104 subordinate line and the λ6708 doublet to derive lithium abundances for 12 members of the Upper Centaurus Lupus and Lower Centaurus Crux subgroups of the Scorpius–Centaurus OB Association. The results indicate any intrinsic Li scatter in our 0.9–1.4 M stars is limited to ∼0.15 dex, consistent with the lack of dispersion in 1.0 M stars in the 100 Myr Pleiades and 30–50 Myr IC 2391 and 2602 clusters. Both ab initio uncertainty estimates and the derived abundances themselves indicate that the λ6104 line yields abundances with equivalent or …
Oxygen In Open Cluster Dwarfs: Pleiades And M34, Simon C. Schuler, Jeremy R. King, L M. Hobbs, Marc H. Pinsonneault
Oxygen In Open Cluster Dwarfs: Pleiades And M34, Simon C. Schuler, Jeremy R. King, L M. Hobbs, Marc H. Pinsonneault
Jeremy R King
We analyze the high-excitation O I lambda7774 triplet in high-resolution, moderate signal-to-noise ratio spectra of 15 Pleiades and eight M34 open cluster dwarfs over the effective temperature range of 5048-6172 K. Relative O abundances have been derived using model atmospheres interpolated from four different sets of ATLAS9 grids. In contrast to existing non-LTE (NLTE) predictions, a dramatic increase in the O I triplet abundance with decreasing temperature is seen for both clusters, regardless of the atmospheric model. S I abundances of three Pleiades stars derived from the high-excitation lambda6053 feature mimic the O I abundance behavior. O abundances have also …
Fe I And Fe Ii Abundances Of Solar-Type Dwarfs In The Pleiades Open Cluster, Simon C. Schuler, Adele L. Plunkett, Jeremy R. King, Marc H. Pinsonneault
Fe I And Fe Ii Abundances Of Solar-Type Dwarfs In The Pleiades Open Cluster, Simon C. Schuler, Adele L. Plunkett, Jeremy R. King, Marc H. Pinsonneault
Jeremy R King
We have derived Fe abundances of 16 solar-type Pleiades dwarfs by means of an equivalent width analysis of Fe I and Fe II lines in high-resolution spectra obtained with the Hobby - Eberly Telescope and High Resolution Spectrograph. Abundances derived from Fe II lines are larger than those derived from Fe I lines (herein referred to as over-ionization) for stars with Teff < 5400 K, and the dis-crepancy (∆Fe = [Fe II/H] - [Fe I/H]) increases dramatically with decreasing Teff, reaching over 0.8 dex for the coolest stars of our sample. The Pleiades joins the open clusters M34, the Hyades, IC2602, and IC2391, and the Ursa Major moving group, demonstrating ostensible over-ionization trends. The Pleiades ∆Fe abun-dances are correlated with Ca II infrared triplet and Hα chromospheric emission indicators and relative differences therein. Oxygen abundances of our Pleiades sample derived from the high-excitation O I triplet have been previously shown to increase with decreasing Teff, and a comparison with the ∆Fe abundances sug-gests that the over-excitation (larger abundances derived from high excitation lines relative to low excitation lines) and over-ionization effects that have been observed in cool open cluster and disk field main sequence (MS) dwarfs share a common origin. Curiously, a correlation between the Pleiades O I abundances and chromospheric emission indicators does not exist. Star-to-star Fe I abun-dances have low internal scatter (< 0.11 dex), but the abundances of stars with Teff< 5400 K are systematically higher compared to the warmer stars. The cool star [Fe I/H] abundances cannot be connected directly to over-excitation effects, but similarities with the ∆Fe and O I triplet trends suggest the abundances are dubious. Using the [Fe I/H] abundances of five stars with Teff > 5400 K, we derive a mean Pleiades cluster metallicity of [Fe/H] = +0.01 ± 0.02.
Lithium In The Upper Centaurus Lupus And Lower Centaurus Crux Subgroups Of Scorpius-Centaurus, Eric J. Bubar, Marc Schaeuble, Jeremy R. King, Eric E. Mamajek, John R. Stauffer
Lithium In The Upper Centaurus Lupus And Lower Centaurus Crux Subgroups Of Scorpius-Centaurus, Eric J. Bubar, Marc Schaeuble, Jeremy R. King, Eric E. Mamajek, John R. Stauffer
Publications
We utilize spectroscopically derived model atmosphere parameters and the Li i λ6104 subordinate line and the λ6708 doublet to derive lithium abundances for 12 members of the Upper Centaurus Lupus and Lower Centaurus Crux subgroups of the Scorpius–Centaurus OB Association. The results indicate any intrinsic Li scatter in our 0.9–1.4 M stars is limited to ∼0.15 dex, consistent with the lack of dispersion in 1.0 M stars in the 100 Myr Pleiades and 30–50 Myr IC 2391 and 2602 clusters. Both ab initio uncertainty estimates and the derived abundances themselves indicate that the λ6104 line yields abundances with equivalent or …
The Chromospheric Activity, Age, Metallicity, And Space Motions Of 36 Wide Binaries, J. K. Zhao, T. D. Oswalt, M. Rudkin, G. Zhao, Y. Q. Chen
The Chromospheric Activity, Age, Metallicity, And Space Motions Of 36 Wide Binaries, J. K. Zhao, T. D. Oswalt, M. Rudkin, G. Zhao, Y. Q. Chen
Publications
We present the chromospheric activity (CA) levels, metallicities, and full space motions for 41 F, G, K, and M dwarf stars in 36 wide binary systems. Thirty-one of the binaries contain a white dwarf (WD) component. In such binaries, the total age can be estimated by adding the cooling age of the WD to an estimate of the progenitor’s main-sequence lifetime. To better understand how CA correlates to stellar age, 14 cluster member stars were also observed. Our observations demonstrate for the first time that, in general, CA decays with age from 50 Myr to at least 8 Gyr for …
Spectroscopic Abundances And Membership In The Wolf 630 Moving Group, Eric J. Bubar, Jeremy R. King
Spectroscopic Abundances And Membership In The Wolf 630 Moving Group, Eric J. Bubar, Jeremy R. King
Publications
The concept of kinematic assemblages evolving from dispersed stellar clusters has remained contentious since Eggen’s initial formulation of moving groups in the 1960s. With high-quality parallaxes from the Hipparcos space astrometry mission, distance measurements for thousands of nearby, seemingly isolated stars are currently available. With these distances, a high-resolution spectroscopic abundance analysis can be brought to bear on the alleged members of these moving groups. If a structure is a relic of an open cluster, the members can be expected to be monolithic in age and abundance in as much as homogeneity is observed in young open clusters. In this …
Fe I And Fe Ii Abundances Of Solar-Type Dwarfs In The Pleiades Open Cluster, Simon C. Schuler, Adele L. Plunkett, Jeremy R. King, Marc H. Pinsonneault
Fe I And Fe Ii Abundances Of Solar-Type Dwarfs In The Pleiades Open Cluster, Simon C. Schuler, Adele L. Plunkett, Jeremy R. King, Marc H. Pinsonneault
Publications
We have derived Fe abundances of 16 solar-type Pleiades dwarfs by means of an equivalent width analysis of Fe I and Fe II lines in high-resolution spectra obtained with the Hobby - Eberly Telescope and High Resolution Spectrograph. Abundances derived from Fe II lines are larger than those derived from Fe I lines (herein referred to as over-ionization) for stars with Teff < 5400 K, and the dis-crepancy (∆Fe = [Fe II/H] - [Fe I/H]) increases dramatically with decreasing Teff, reaching over 0.8 dex for the coolest stars of our sample. The Pleiades joins the open clusters M34, the Hyades, IC2602, and IC2391, and the Ursa Major moving group, demonstrating ostensible over-ionization trends. The Pleiades ∆Fe abun-dances are correlated with Ca II infrared triplet and Hα chromospheric emission indicators and relative differences therein. Oxygen abundances of our Pleiades sample derived from the high-excitation O I triplet have been previously shown to increase with decreasing Teff, and a comparison with the ∆Fe abundances sug-gests that the over-excitation (larger abundances derived from high excitation lines relative to low excitation lines) and over-ionization effects that have been observed in cool open cluster and disk field main sequence (MS) dwarfs share a common origin. Curiously, a correlation between the Pleiades O I abundances and chromospheric emission indicators does not exist. Star-to-star Fe I abun-dances have low internal scatter (< 0.11 dex), but the abundances of stars with Teff< 5400 K are systematically higher compared to the warmer stars. The cool star [Fe I/H] abundances cannot be connected directly to over-excitation effects, but similarities with the ∆Fe and O I triplet trends suggest the abundances are dubious. Using the [Fe I/H] abundances of five stars with Teff > 5400 K, we derive a mean Pleiades cluster metallicity of [Fe/H] = +0.01 ± 0.02.
Spectrophotometrically Identified Stars In The Pears-N And Pears-S Fields., N. Pirzkal, A. J. Burgasser, S. Malhotra, Benne W. Holwerda, K. C. Sahu, J. E. Rhoads, C. Xu, J. J. Bochanski, J. R. Walsh, R. A. Windhorst, N. P. Hathi, S. H. Cohen
Spectrophotometrically Identified Stars In The Pears-N And Pears-S Fields., N. Pirzkal, A. J. Burgasser, S. Malhotra, Benne W. Holwerda, K. C. Sahu, J. E. Rhoads, C. Xu, J. J. Bochanski, J. R. Walsh, R. A. Windhorst, N. P. Hathi, S. H. Cohen
Faculty Scholarship
Deep ACS slitless grism observations and identification of stellar sources are presented within the Great Observatories Origins Deep Survey North and South fields which were obtained in the Probing Evolution And Reionization Spectroscopically (PEARS) program. It is demonstrated that even low-resolution spectra can be a very powerful means of identifying stars in the field, especially low-mass stars with stellar types M0 and later. The PEARS fields lay within the larger GOODS fields, and we used new, deeper images to further refine the selection of stars in the PEARS field, down to a magnitude of z850 = 25 using a newly …
Improved Photometric Calibrations For Red Stars Observed With The Sdss Photometric Telescope, James R. A. Davenport, John J. Bochanski, Kevin R. Covey, Suzanne L. Hawley, Andrew A. West, Doanld P. Schneider
Improved Photometric Calibrations For Red Stars Observed With The Sdss Photometric Telescope, James R. A. Davenport, John J. Bochanski, Kevin R. Covey, Suzanne L. Hawley, Andrew A. West, Doanld P. Schneider
Physics & Astronomy
We present a new set of photometric transformations for red stars observed with the Sloan Digital Sky Survey (SDSS) 0.5 m Photometric Telescope (PT) and the SDSS 2.5 m telescope at the Apache Point Observatory in New Mexico. Nightly PT observations of US Naval Observatory standards are used to determine extinction corrections and calibration terms for SDSS 2.5 m photometry. Systematic differences between the PT and native SDSS 2.5 m ugriz photometry require conversions between the two systems which have previously been undefined for the reddest stars. By matching ~43,000 stars observed with both the PT and SDSS 2.5 m, …
Lp133-373 A New Chromospherically Active Eclipsing Dme Binary With A Distant, Cool White Dwarf Companion, T. R. Vaccaro, T. D. Oswalt, M. Rudkin, Adela Kawka, Stephane Vennes, Et Al.
Lp133-373 A New Chromospherically Active Eclipsing Dme Binary With A Distant, Cool White Dwarf Companion, T. R. Vaccaro, T. D. Oswalt, M. Rudkin, Adela Kawka, Stephane Vennes, Et Al.
Publications
We report the discovery of the partially eclipsing binary LP 133-373. Nearly identical eclipses along with observed photometric colors and spectroscopy indicate that it is a pair of chromospherically active dM4 stars in a circular 1.6 day orbit. Light and velocity curve modeling to our differential photometry and velocity data show that each star has a mass and radius of 0.340 ± 0.014 M☉ and 0.33 ± 0.02 R☉. The binary is itself part of a common proper motion pair with LP 133-374, a cool DC or possible DA white dwarf with a mass of 0.49-0.82 M☉, …
Lp 133-373: A New Chromospherically Active Eclipsing Dme Binary With A Distant, Cool White Dwarf Companion, T. R. Vaccaro, M. Rudkin, A. Kawka, S. Vennes, Terry D. Oswalt, Et Al.
Lp 133-373: A New Chromospherically Active Eclipsing Dme Binary With A Distant, Cool White Dwarf Companion, T. R. Vaccaro, M. Rudkin, A. Kawka, S. Vennes, Terry D. Oswalt, Et Al.
Publications
We report the discovery of the partially eclipsing binary LP 133-373. Nearly identical eclipses along with observed photometric colors and spectroscopy indicate that it is a pair of chromospherically active dM4 stars in a circular 1.6 day orbit. Light and velocity curve modeling to our differential photometry and velocity data show that each star has a mass and radius of 0:340 ± 0:014 MꙨ and 0:33 ± 0:02 RꙨ. The binary is itself part of a common proper motion pair with LP 133-374, a cool DC or possible DA white dwarf with a mass of 0.49Y0.82 M …
Possible Identification Of A Metal-Rich Old Moving Group: High-Resolution Spectroscopy Of Candidate Members, Abigail R. Daane, Jeremy R. King, Simon C. Schuler
Possible Identification Of A Metal-Rich Old Moving Group: High-Resolution Spectroscopy Of Candidate Members, Abigail R. Daane, Jeremy R. King, Simon C. Schuler
Publications
Using new high-resolution spectroscopic observations from both the McDonald Observatory 2.7 m and Kitt Peak National Observatory 4 m telescopes, we observed four candidate members of the Ursa Major moving group previously suggested to instead belong to a significantly older kinematic assemblage. The Fe abundances we measure strongly suggest that these stars are not UMa members but form a more metal-rich group of stars (+0.10 ≤ [Fe/H] ≤ +0.18) with an age near 3 Gyr. Our [Ca/H] determinations corroborate this result. The apparent similarities in metallicity and previously discovered UVW space motions lend credence to prior suggestions that these stars …
Oxygen In Open Cluster Dwarfs: Pleiades And M34, Simon C. Schuler, Jeremy R. King, L M. Hobbs, Marc H. Pinsonneault
Oxygen In Open Cluster Dwarfs: Pleiades And M34, Simon C. Schuler, Jeremy R. King, L M. Hobbs, Marc H. Pinsonneault
Publications
We analyze the high-excitation O I lambda7774 triplet in high-resolution, moderate signal-to-noise ratio spectra of 15 Pleiades and eight M34 open cluster dwarfs over the effective temperature range of 5048-6172 K. Relative O abundances have been derived using model atmospheres interpolated from four different sets of ATLAS9 grids. In contrast to existing non-LTE (NLTE) predictions, a dramatic increase in the O I triplet abundance with decreasing temperature is seen for both clusters, regardless of the atmospheric model. S I abundances of three Pleiades stars derived from the high-excitation lambda6053 feature mimic the O I abundance behavior. O abundances have also …