39 results on '"Phillip Cargile"'
Search Results
2. The Galactic Distribution of Phosphorus: A Survey of 163 Disk and Halo Stars*
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Zachary G. Maas, Keith Hawkins, Natalie R. Hinkel, Phillip Cargile, Steven Janowiecki, and Tyler Nelson
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- 2022
- Full Text
- View/download PDF
3. Birth of a Be star: an APOGEE search for Be stars forming through binary mass transfer
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Kareem El-Badry, Charlie Conroy, Eliot Quataert, Hans-Walter Rix, Jonathan Labadie-Bartz, Tharindu Jayasinghe, Todd Thompson, Phillip Cargile, Keivan G Stassun, and Ilya Ilyin
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Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,FOS: Physical sciences ,Astronomy and Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
Motivated by recent suggestions that many Be stars form through binary mass transfer, we searched the APOGEE survey for Be stars with bloated, stripped companions. From a well-defined parent sample of 297 Be stars, we identified one mass-transfer binary, HD 15124. The object consists of a main-sequence Be star ($M_{\rm Be}=5.3\pm 0.6 \,M_{\odot}$) with a low-mass ($M_{\rm donor}=0.92\pm 0.22\,M_{\odot}$), subgiant companion on a 5.47-day orbit. The emission lines originate in an accretion disk caused by ongoing mass transfer, not from a decretion disk as in classical Be stars. Both stars have surface abundances bearing imprint of CNO processing in the donor's core: the surface helium fraction is $Y_{\rm He}\approx 0.6$, and the nitrogen-to-carbon ratio is 1000 times the solar value. The system's properties are well-matched by binary evolution models in which mass transfer begins while a $3-5\,M_{\odot}$ donor leaves the main sequence, with the secondary becoming the Be star. These models predict that the system will soon become a detached Be + stripped star binary like HR 6819 and LB-1, with the stripped donor eventually contracting to become a core helium-burning sdOB star. Discovery of one object in this short-lived ($\sim$1 Myr) evolutionary phase implies the existence of many more that have already passed through it and are now Be + sdOB binaries. We infer that $(28_{-16}^{+27})\,\%$ of Be stars have stripped companions, most of which are faint. Together with the dearth of main-sequence companions to Be stars and recent discovery of numerous Be + sdOB binaries in the UV, our results imply that binarity plays an important role in the formation of Be stars., 25 pages, 19 figures, accepted to MNRAS
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- 2022
4. Wide binaries from the H3 survey: the thick disk and halo have similar wide binary fractions
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Hsiang-Chih Hwang, Yuan-Sen Ting, Charlie Conroy, Nadia L Zakamska, Kareem El-Badry, Phillip Cargile, Dennis Zaritsky, Vedant Chandra, Jiwon Jesse Han, Joshua S Speagle, and Ana Bonaca
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Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics - Abstract
Due to the different environments in the Milky Way's disk and halo, comparing wide binaries in the disk and halo is key to understanding wide binary formation and evolution. By using Gaia Early Data Release 3, we search for resolved wide binary companions in the H3 survey, a spectroscopic survey that has compiled $\sim$150,000 spectra for thick-disk and halo stars to date. We identify 800 high-confidence (a contamination rate of 4%) wide binaries and two resolved triples, with binary separations mostly between $10^3$-$10^5$ AU and a lowest [Fe/H] of $-2.7$. Based on their Galactic kinematics, 33 of them are halo wide binaries, and most of those are associated with the accreted Gaia-Sausage-Enceladus galaxy. The wide binary fraction in the thick disk decreases toward the low metallicity end, consistent with the previous findings for the thin disk. Our key finding is that the halo wide binary fraction is consistent with the thick-disk stars at a fixed [Fe/H]. There is no significant dependence of the wide binary fraction on the $\alpha$-captured abundance. Therefore, the wide binary fraction is mainly determined by the iron abundance, not their disk or halo origin nor the $\alpha$-captured abundance. Our results suggest that the formation environments play a major role for the wide binary fraction, instead of other processes like radial migration that only apply to disk stars., Comment: Accepted for publication in MNRAS. Fig. 7 is the key plot. Online data are available at: https://drive.google.com/file/d/1TXKEwKBHcP4j9tMeJpa2hWDFHsEc1Qd3/view?usp=sharing. Comments are welcome!
- Published
- 2021
5. Evidence from Disrupted Halo Dwarfs that r-process Enrichment via Neutron Star Mergers is Delayed by ≳500 Myr
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Rohan P. Naidu, Alexander P. Ji, Charlie Conroy, Ana Bonaca, Yuan-Sen Ting, Dennis Zaritsky, Lieke A. C. van Son, Floor S. Broekgaarden, Sandro Tacchella, Vedant Chandra, Nelson Caldwell, Phillip Cargile, and Joshua S. Speagle
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
The astrophysical origins of $r$-process elements remain elusive. Neutron star mergers (NSMs) and special classes of core-collapse supernovae (rCCSNe) are leading candidates. Due to these channels' distinct characteristic timescales (rCCSNe: prompt, NSMs: delayed), measuring $r$-process enrichment in galaxies of similar mass, but differing star-formation durations might prove informative. Two recently discovered disrupted dwarfs in the Milky Way's stellar halo, Kraken and \textit{Gaia}-Sausage Enceladus (GSE), afford precisely this opportunity: both have $M_{\star}\approx10^{8}M_{\rm{\odot}}$, but differing star-formation durations of ${\approx}2$ Gyrs and ${\approx}3.6$ Gyrs. Here we present $R\approx50,000$ Magellan/MIKE spectroscopy for 31 stars from these systems, detecting the $r$-process element Eu in all stars. Stars from both systems have similar [Mg/H]$\approx-1$, but Kraken has a median [Eu/Mg]$\approx-0.1$ while GSE has an elevated [Eu/Mg]$\approx0.2$. With simple models we argue NSM enrichment must be delayed by $500-1000$ Myrs to produce this difference. rCCSNe must also contribute, especially at early epochs, otherwise stars formed during the delay period would be Eu-free. In this picture, rCCSNe account for $\approx50\%$ of the Eu in Kraken, $\approx25\%$ in GSE, and $\approx15\%$ in dwarfs with extended star-formation durations like Sagittarius. The inferred delay time for NSM enrichment is $10-100\times$ longer than merger delay times from stellar population synthesis -- this is not necessarily surprising because the enrichment delay includes time taken for NSM ejecta to be incorporated into subsequent generations of stars. For example, this may be due to natal kicks that result in $r$-enriched material deposited far from star-forming gas, which then takes $\approx10^{8}-10^{9}$ years to cool in these galaxies., Comment: Submitted to ApJL. Figure 3 shows the key empirical result, and Figure 5 summarizes the proposed scenario. Comments very welcome!
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- 2022
6. Exploiting kinematics and UBVIc photometry to establish high fidelity membership of the open cluster Blanco 1
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J. C. Mermilliod, Imants Platais, A. Steinhauer, Phillip Cargile, David James, and C. Deliyannis
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Physics ,Milky Way ,Astronomy ,Astronomy and Astrophysics ,Astrometry ,Astrophysics ,Kinematics ,law.invention ,Square degree ,Telescope ,Photometry (optics) ,High fidelity ,Space and Planetary Science ,law ,Open cluster - Abstract
We present the results of a wide-field, high-precision UBVIc CCD photometric survey of the Galactic open cluster Blanco 1. Standardized photometry was acquired using the Y4Kcam on the SMARTS 1m telescope at CTIO. We have also determined new high-precision proper motions (σμ = 0.3 mas yr−1) over an eight square degree area down to V = 16.5. Combined with 1D kinematic data, our survey yields a complete list of cluster members down to ~ 0.5 M⊙ and new high-fidelity color-magnitude diagrams are presented for Blanco 1. Having established a bona fide membership catalog, astrophysical characteristics of solar-type cluster members such as X-ray activity and lithium abundance have been studied to gain more insights in the process of internal mixing and convection. Our new results should also help to better understand its peculiar location in the Milky Way and to unravel its dynamical history.
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- 2017
7. A deep proper-motion survey of the nearby open cluster Blanco 1★†
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Sydney A. Barnes, Carlos E. Lopez, J. C. Mermilliod, Dimitri Pourbaix, David James, D. Castillo, Estelle Moraux, Brian McLean, Imants Platais, K. Vieira, Phillip Cargile, Charles Loomis, and Terrence M. Girard
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Physics ,Stellar kinematics ,Star cluster ,Proper motion ,Space and Planetary Science ,Stellar dynamics ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,Astrometry ,Pleiades ,Parallax ,Open cluster - Abstract
We provide two comprehensive catalogues of positions and proper motions in the area of open cluster Blanco 1. The main catalogue, CtlgM, contains 6271 objects down to V similar to 18.5 and covers a circular similar to 11 deg2 area. The accuracy of CtlgM proper motions, at about 0.3-0.5 mas yr-1 for well-measured stars, permits an excellent segregation between the cluster and field stars. The vector-point diagram of proper motions indicates an estimated total of similar to 165 cluster members among the stars in our sample, while 314 stars with Sigma(mu) = 1 per cent. We also explored the astrometric potential of the Catalogue of Objects and Measured Parameters from All Sky Surveys (COMPASS) data base in order to obtain additional proper motions for fainter stars in the area of Blanco 1. This effort produced the second catalogue of proper motions, CtlgD, containing 11 598 objects down to V similar to 21. A total of 4273 objects are common between the two catalogues. The accuracy of proper motions in CtlgD ranges from 1.0 to 6 mas yr-1. A combination of both proper-motion catalogues was instrumental in confirming that Blanco 1 contains a large population of M dwarfs (similar to 150 down to M5 V - the limit of our survey). In many respects, Blanco 1 is a scaled down 'twin' of the Pleiades. The noted discrepancy between the distance from a new Hipparcos parallax of Blanco 1 and the cluster's photometric distance, at least partially, might be due to the apparent correlation between parallax and proper motion in right ascension for the ensemble of cluster members.
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- 2011
8. Techniques for Finding Close-in, Low-mass Planets around Evolved Intermediate-mass Stars
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John Asher Johnson, Phillip Cargile, Amber Medina, and Jason D. Eastman
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Physics ,010504 meteorology & atmospheric sciences ,Stellar mass ,Subgiant ,Astronomy and Astrophysics ,Astrophysics ,Radius ,01 natural sciences ,Asteroseismology ,Radial velocity ,Stars ,13. Climate action ,Space and Planetary Science ,Planet ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Low Mass ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences - Abstract
Jupiter-mass planets with large semimajor axes (a > 1.0 au) occur at a higher rate around evolved intermediate-mass stars. There is a pronounced paucity of close-in (a < 0.6 au), intermediate-period (5 < P < 100 days), low-mass (M planet < 0.7M Jup ) planets, known as the "Planet Desert." Current radial velocity (RV) methods have yet to yield close-in, low-mass planets around these stars because the planetary signals could be hidden by the (5–10) m s−1 RV variations caused by acoustic oscillations. We find that by implementing an observing strategy of taking three observations per night separated by an optimal Δt, which is a function of the oscillation periods and amplitudes, we can average over the stellar jitter and improve our sensitivity to low-mass planets. We find that Δt can be approximated using the stellar mass and radius given by the relationship Δt = 1.79 . We test our proposed method by injecting planets into well-sampled data of a subgiant star, γ Cep. We compare the fraction of planets recovered by our method to the fraction of planets recovered using current RV observational strategies. We find that our method decreases the rms of the stellar jitter due to acoustic oscillations by a factor of three over current single epoch observing strategies used for subgiant stars. Our observing strategy provides a means to test whether the Planet Desert extends to lower-mass planets.
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- 2018
9. A NEW X-RAY ANALYSIS OF THE OPEN CLUSTER BLANCO 1 USING WIDE-FIELDBVIcPHOTOMETRIC AND PROPER MOTION SURVEYS
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Phillip Cargile, Imants Platais, and David James
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Proper motion ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Stellar classification ,01 natural sciences ,Photometry (optics) ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,0103 physical sciences ,ROSAT ,Cluster (physics) ,Astrophysics - High Energy Astrophysical Phenomena ,Pleiades ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Open cluster - Abstract
We perform a new analysis of the extant ROSAT and XMM-Newton X-ray surveys of the southern open cluster Blanco 1, utilizing new BVIc photometric and proper motion data sets. In our study, we match optical counterparts to 47 X-ray sources associated with Blanco 1 cluster members, 6 of which were listed in previous X-ray studies as cluster nonmembers. Our new catalog of optical counterparts to X-ray sources clearly traces out the Blanco 1 main sequence in a CMD, extending from early G to mid-M spectral types. Additionally, we derive new Lx as well as Lx/Lbol ratios for confirmed cluster members. We compare these X-ray properties to other young open clusters, including the coeval Pleiades cluster, to investigate the relationship between age and X-ray activity. We find that stars in Blanco 1 generally exhibit X-ray properties similar to those of other open clusters, namely increasing Lx/Lbol with reducing mass for earlier-type stars, and a saturation limit of Lx/Lbol at a magnitude of 10^-3 for stars with V-Ic > 1.25. More generally, the X-ray detected stars in Blanco 1 have X-ray emission magnitudes that agree with the overall trends seen in the other young clusters. In a direct comparison of Blanco 1 to the Pleiades open cluster, members of both clusters have similar X-ray characteristics; however, there does appear to be some discrepancies in the distribution of Lx/Lbol as a function of color that may be related to scatter seen in the Pleiades CMD. Moreover, previous comparisons of this nature for Blanco 1 were not possible due to the reliance on photographic photometry. This is where the power of precise, homogeneous, and standardized CCD photometry allows for a high fidelity, detailed study of the X-ray properties of stars in Blanco 1. [abridged], 16 Pages, 11 Figures, 4 Tables, accepted for publication in The Astronomical Journal
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- 2009
10. Membership, binarity, and rotation of F-G-K stars in the open cluster Blanco 1
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Phillip Cargile, M. Grenon, Imants Platais, David James, and J. C. Mermilliod
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Physics ,Proper motion ,Astronomy ,Astronomy and Astrophysics ,Context (language use) ,Astrophysics ,Stars ,Star cluster ,Galaxy groups and clusters ,Space and Planetary Science ,Pleiades ,Astrophysics::Galaxy Astrophysics ,Galaxy cluster ,Open cluster - Abstract
Context. The nearby open cluster Blanco 1 is of considerable astrophysical interest for formation and evolution studies of open clusters because it is the third highest Galactic latitude cluster known. It has been observed often, but so far no definitive and comprehensive membership determination is readily available.
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- 2008
11. Discovery of Par 1802 as a Low‐Mass, Pre‐Main‐Sequence Eclipsing Binary in the Orion Star‐Forming Region
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Keivan G. Stassun, Robert D. Mathieu, and Phillip Cargile
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Physics ,010504 meteorology & atmospheric sciences ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Binary number ,Astronomy and Astrophysics ,Radius ,Astrophysics ,01 natural sciences ,Stars ,Orbit ,Space and Planetary Science ,0103 physical sciences ,Orion Nebula ,Cluster (physics) ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,10. No inequality ,Low Mass ,010303 astronomy & astrophysics ,Stellar evolution ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences - Abstract
We report the discovery of a pre-main-sequence, low-mass, double-lined, spectroscopic, eclipsing binary in the Orion star-forming region. We present our observations including radial velocities derived from optical high-resolution spectroscopy, and present an orbit solution that permits the determination of precise empirical masses for both components of the system. We measure that Par 1802 is composed of two equal mass (0.39+-0.03, 0.40+-0.03 Msun) stars in a circular, 4.7 day orbit. There is strong evidence, such as the system exhibiting strong Li lines and a center-of-mass velocity consistent with cluster membership, that this system is a member of the Orion star-forming region and quite possibly the Orion Nebula Cluster, and therefore has an age of only a few million years. As there are currently only a few empirical mass and radius measurements for low-mass, PMS stars, this system presents an interesting test for the predictions of current theoretical models of pre-main sequence stellar evolution., 21 pages, 6 figures, 2 tables; Fig 2 caption edited
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- 2008
12. The EBLM project. II. A very hot, low-mass M dwarf in an eccentric and long-period, eclipsing binary system from the SuperWASP Survey
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Rory Barnes, Amaury H. M. J. Triaud, Denise C. Stephens, Michael D. Joner, Florian Rodler, Leslie Hebb, Enrique Garcia-Melendo, A. Collier Cameron, M. Lopez-Morales, Keivan G. Stassun, Francesca Faedi, Phillip Cargile, I. Skillen, James McCormac, Pilar Montañés-Rodríguez, Y. Gómez Maqueo Chew, C. D. Laney, J. C. Morales, Suvrath Mahadevan, Rohit Deshpande, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. TUAREG - Turbulence and Aerodynamics in Mechanical and Aerospace Engineering Research Group, Science & Technology Facilities Council, PPARC - Now STFC, and University of St Andrews. School of Physics and Astronomy
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Radial velocities ,FOS: Physical sciences ,Planets ,Orbital eccentricity ,Individual ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Photometric ,fundamental parameters [Stars] ,2MASS J01135129+3149097 ,low-mass [Stars] ,Planet ,Fundamental parameters ,Fotometria astronòmica ,QB Astronomy ,Astrophysics::Solar and Stellar Astrophysics ,Binary system ,Planetes ,Eclipsing ,QC ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,QB ,individual: 2MASS J01135129+3149097 [Stars] ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,radial velocities [Techniques] ,eclipsing [Binaries] ,photometric [Techniques] ,Binaries ,Astronomical photometry ,Astronomy and Astrophysics ,Low-mass ,Orbital period ,Light curve ,Stars ,Techniques ,Estels ,Orbit ,QC Physics ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,Física::Astronomia i astrofísica [Àrees temàtiques de la UPC] ,Astrophysics::Earth and Planetary Astrophysics ,Low Mass ,Astrophysics - Earth and Planetary Astrophysics - Abstract
In this paper, we derive the fundamental properties of 1SWASPJ011351.29+314909.7 (J0113+31), a metal-poor (-0.40 +/- 0.04 dex), eclipsing binary in an eccentric orbit (~0.3) with an orbital period of ~14.277 d. Eclipsing M dwarfs orbiting solar-type stars (EBLMs), like J0113+31, have been identified from WASP light curves and follow-up spectroscopy in the course of the transiting planet search. We present the first binary of the EBLM sample to be fully analysed, and thus, define here the methodology. The primary component with a mass of 0.945 +/- 0.045 Msun has a large radius (1.378 +/- 0.058 Rsun) indicating that the system is quite old, ~9.5 Gyr. The M-dwarf secondary mass of 0.186 +/- 0.010 Msun and radius of 0.209 +/- 0.011 Rsun are fully consistent with stellar evolutionary models. However, from the near-infrared secondary eclipse light curve, the M dwarf is found to have an effective temperature of 3922 +/- 42 K, which is ~600 K hotter than predicted by theoretical models. We discuss different scenarios to explain this temperature discrepancy. The case of J0113+31 for which we can measure mass, radius, temperature and metallicity, highlights the importance of deriving mass, radius and temperature as a function of metallicity for M dwarfs to better understand the lowest mass stars. The EBLM Project will define the relationship between mass, radius, temperature and metallicity for M dwarfs providing important empirical constraints at the bottom of the main sequence., Comment: 13 pages, 7 figures. Accepted for publication in A&A
- Published
- 2014
13. KELT-6b: A P ~ 7.9 Day Hot Saturn Transiting a Metal-poor Star with a Long-period Companion
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Gilbert A. Esquerdo, Eric L. N. Jensen, Sasha Hinkley, Patricia Trueblood, Qingqing Mao, Matthew T. Penny, John F. Kielkopf, Darren L. DePoy, Alexander J. W. Richert, Debra A. Fischer, John Asher Johnson, Robert J. Siverd, Andrew Gould, Allyson Bieryla, Karen A. Collins, Ryan L. Avril, Jennifer L. Marshall, Kaloyan Penev, Joao Gregorio, Richard W. Pogge, Rachel Street, B. Scott Gaudi, Thomas E. Oberst, Lars A. Buchhave, Mark Trueblood, David W. Latham, Andrew W. Howard, Samuel N. Mellon, Ryan J. Oelkers, Justin R. Crepp, Thomas G. Beatty, Mark Manner, Benjamin J. Fulton, Robert P. Stefanik, Michael L. Calkins, Keivan G. Stassun, Jason D. Eastman, Phillip Cargile, Kim K. McLeod, Perry Berlind, Claude E. Mack, and Joshua Pepper
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Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Ephemeris ,Surface gravity ,01 natural sciences ,Radial velocity ,Photometry (optics) ,Stars ,13. Climate action ,Space and Planetary Science ,Planet ,0103 physical sciences ,Spectroscopy ,010303 astronomy & astrophysics ,Planetary mass ,Astrophysics - Earth and Planetary Astrophysics ,0105 earth and related environmental sciences - Abstract
We report the discovery of KELT-6b, a mildly-inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V=10.38 host star (BD+31 2447) is a mildly evolved, late-F star with T_eff=6102 \pm 43 K, log(g_*)=4.07_{-0.07}^{+0.04} and [Fe/H]=-0.28 \pm 0.04, with an inferred mass M_*=1.09 \pm 0.04 M_sun and radius R_star=1.58_{-0.09}^{+0.16} R_sun. The planetary companion has mass M_P=0.43 \pm 0.05 M_J, radius R_P=1.19_{-0.08}^{+0.13} R_J, surface gravity log(g_P)=2.86_{-0.08}^{+0.06}, and density rho_P=0.31_{-0.08}^{+0.07} g~cm^{-3}. The planet is on an orbit with semimajor axis a=0.079 \pm 0.001 AU and eccentricity e=0.22_{-0.10}^{+0.12}, which is roughly consistent with circular, and has ephemeris of T_c(BJD_TDB)=2456347.79679 \pm 0.00036 and P=7.845631 \pm 0.000046 d. Equally plausible fits that employ empirical constraints on the host star parameters rather than isochrones yield a larger planet mass and radius by ~4-7%. KELT-6b has surface gravity and incident flux similar to HD209458b, but orbits a host that is more metal poor than HD209458 by ~0.3 dex. Thus, the KELT-6 system offers an opportunity to perform a comparative measurement of two similar planets in similar environments around stars of very different metallicities. The precise radial velocity data also reveal an acceleration indicative of a longer-period third body in the system, although the companion is not detected in Keck adaptive optics images., Comment: Published in AJ, 17 pages, 15 figures, 6 tables
- Published
- 2014
14. A Cautionary Tale: MARVELS Brown Dwarf Candidate Reveals Itself To Be A Very Long Period, Highly Eccentric Spectroscopic Stellar Binary
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Arpita Roy, Stephen R. Kane, Leslie Hebb, B. Scott Gaudi, Kaike Pan, Jonay I. González Hernández, Stephanie A. Snedden, Luan Ghezzi, Rohit Deshpande, Carlos Allende Prieto, Massimiliano Esposito, Benjamin M. Tofflemire, Phillip Cargile, Daniel Oravetz, Robert J. Siverd, Rafael Rebolo, Audrey Simmons, Martin Paegert, Eric Agol, Thomas G. Beatty, Brian C. Lee, Claude E. Mack, Peng Jiang, Elena Malanushenko, Nathan De Lee, V. Malanushenko, Keivan G. Stassun, Daniel Mata Sánchez, John P. Wisniewski, Luiz N. da Costa, Dmitry Bizyaev, Howard Brewington, Gustavo F. Porto de Mello, Justin R. Crepp, Joshua Peper, Suvrath Mahadevan, Scott W. Fleming, Bruno Femenia, Donald P. Schneider, Jian Ge, G. Ebelke, Jason D. Eastman, Marcio A. G. Maia, Leticia D. Ferreira, and Basilio X. Santiago
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010504 meteorology & atmospheric sciences ,media_common.quotation_subject ,Brown dwarf ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,spectroscopic [Binaries] ,0103 physical sciences ,Binary star ,Astrophysics::Solar and Stellar Astrophysics ,Circular orbit ,Eccentricity (behavior) ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,media_common ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Orbital elements ,individual (TYC 3010-1494-1) [Stars] ,Line-of-sight ,Brown dwarfs ,Astronomy and Astrophysics ,Stars ,Orbit ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Anãs marrons ,Astrophysics::Earth and Planetary Astrophysics ,Estrelas binarias ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R ~, 16 pages, 11 figures, 6 tables
- Published
- 2013
15. Evaluating Gyrochronology on the Zero-Age-Main-Sequence: Rotation Periods in the Southern Open Cluster Blanco 1 from the KELT-South Survey
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Rudolf B. Kuhn, Phillip Cargile, David James, Joshua Pepper, Keivan G. Stassun, and Robert J. Siverd
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Physics ,Rotation period ,Stellar mass ,010308 nuclear & particles physics ,Stellar rotation ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Rotation ,01 natural sciences ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Gyrochronology ,Astrophysics::Earth and Planetary Astrophysics ,Pleiades ,010303 astronomy & astrophysics ,Stellar evolution ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Open cluster - Abstract
We report periods for 33 members of Blanco 1 as measured from KELT-South light curves, the first reported rotation periods for this benchmark zero-age-main-sequence open cluster. The distribution of these stars spans from late-A or early-F dwarfs to mid-K with periods ranging from less than a day to ~8 days. The rotation period distribution has a morphology similar to the coeval Pleiades cluster, suggesting the universal nature of stellar rotation distributions. Employing two different gyrochronology methods, we find an age of 146+13-14 Myr for the cluster. Using the same techniques, we infer an age of 134+9-10 Myr for the Pleiades measured from existing literature rotation periods. These rotation-derived ages agree with independently determined cluster ages based on the lithium depletion boundary technique. Additionally, we evaluate different gyrochronology models, and quantify levels of agreement between the models and the Blanco 1/Pleiades rotation period distributions, including incorporating the rotation distributions of clusters at ages up to 1.1 Gyr. We find the Skumanich-like spin-down rate sufficiently describes the rotation evolution of stars hotter than the Sun; however, we find cooler stars rotating faster than predicted by a Skumanich-law, suggesting a mass dependence in the efficiency of stellar angular momentum loss rate. Finally, we compare the Blanco 1 and Pleiades rotation period distributions to available non-linear angular momentum evolution models. We find they require a significant mass dependence on the initial rotation rate of solar-type stars to reproduce the observed range of rotation periods at a given stellar mass, and are furthermore unable to predict the observed over-density of stars along the upper-envelope of the clusters' rotation distributions., Comment: 19 pages,14 figures, 3 tables -- Accepted for publication in ApJ
- Published
- 2013
- Full Text
- View/download PDF
16. Identification of the Lithium Depletion Boundary and Age of the Southern Open Cluster Blanco 1
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Phillip Cargile, R. D. Jeffries, and David James
- Subjects
Physics ,Stellar mass ,010308 nuclear & particles physics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Stars ,Star cluster ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,0103 physical sciences ,Cluster (physics) ,Mass segregation ,Low Mass ,010303 astronomy & astrophysics ,Stellar evolution ,Solar and Stellar Astrophysics (astro-ph.SR) ,Open cluster - Abstract
We present results from a spectroscopic study of the very low mass members of the Southern open cluster Blanco 1 using the Gemini-N telescope. We obtained intermediate resolution (R~4400) GMOS spectra for 15 cluster candidate members with I~14-20 mag, and employed a series of membership criteria - proximity to the cluster's sequence in an I/I-Ks color-magnitude diagram (CMD), kinematics agreeing with the cluster systemic motion, magnetic activity as a youth indicator - to classify 10 of these objects as probable cluster members. For these objects, we searched for the presence of the Li I 6708 A feature to identify the lithium depletion boundary (LDB) in Blanco 1. The I/I-Ks CMD shows a clear mass segregation in the Li distribution along the cluster sequence; namely, all higher mass stars are found to be Li-poor, while lower mass stars are found to be Li-rich. The division between Li-poor and Li-rich (i.e., the LDB) in Blanco 1 is found at I=$18.78 \pm 0.24$ and I-Ks=$3.05 \pm 0.10$. Using current pre-main-sequence evolutionary models we determine an LDB age of $132 \pm 24$ Myr. Comparing our derived LDB age to upper-main-sequence isochrone ages for Blanco 1, as well as for other open clusters with identified LDBs, we find good chronometric consistency when using stellar evolution models that incorporate a moderate degree of convective core overshoot., 6 pages, 3 figures, Accepted for Publication in the Astrophysical Journal Letters
- Published
- 2010
17. Debris Disks of Members of the Blanco 1 Open Cluster
- Author
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Scott J. Wolk, D. Barrado y Navascues, Luisa Rebull, John M. Carpenter, D. James, Michael Meyer, Giuseppina Micela, S. E. Strom, Phillip Cargile, Alberto Noriega-Crespo, Dana E. Backman, and John Stauffer
- Subjects
Physics ,Debris disk ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Photometry (optics) ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Spitzer Space Telescope ,Space and Planetary Science ,Binary star ,Pleiades ,Low Mass ,Solar and Stellar Astrophysics (astro-ph.SR) ,Open cluster - Abstract
We have used the Spitzer Space Telescope to obtain Multiband Imaging Photometer for Spitzer (MIPS) 24 um photometry for 37 members of the ~100 Myr old open cluster Blanco 1. For the brightest 25 of these stars (where we have 3sigma uncertainties less than 15%), we find significant mid-IR excesses for eight stars, corresponding to a debris disk detection frequency of about 32%. The stars with excesses include two A stars, four F dwarfs and two G dwarfs. The most significant linkage between 24 um excess and any other stellar property for our Blanco 1 sample of stars is with binarity. Blanco 1 members that are photometric binaries show few or no detected 24 um excesses whereas a quarter of the apparently single Blanco 1 members do have excesses. We have examined the MIPS data for two other clusters of similar age to Blanco 1 -- NGC 2547 and the Pleiades. The AFGK photometric binary star members of both of these clusters also show a much lower frequency of 24 um excesses compared to stars that lie near the single-star main sequence. We provide a new determination of the relation between V-Ks color and Ks-[24] color for main sequence photospheres based on Hyades members observed with MIPS. As a result of our analysis of the Hyades data, we identify three low mass Hyades members as candidates for having debris disks near the MIPS detection limit., Comment: Accepted to ApJ
- Published
- 2010
- Full Text
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18. Employing a New BVIc Photometric Survey of IC 4665 to Investigate the Age of this Young Open Cluster
- Author
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David J. James and Phillip Cargile
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,myr ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,0103 physical sciences ,Cluster (physics) ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Open cluster - Abstract
We present a new, BVIc photometric survey of the young open cluster IC4665, which improves on previous studies of this young cluster by incorporating a rigorous standardization procedure, thus providing high-fidelity colors and magnitudes for cluster members. We use this new photometric dataset to reevaluate the properties (age and distance) of IC4665. Namely, using a statistical approach incorporating Tau^2 CMD modeling, we measure a pre-main-sequence isochrone age and distance of 36+-9 Myr and 360+-12 pc, as well as a upper-main-sequence turn-off age and distance of 42+-12 Myr and 357+-12 pc. These ages and distances are highly dependent on the isochrone model and color used for the fitting procedure, with a possible range of ~10-20 Myr in age and ~20 pc in distance. This spread in calculated ages and distances seen between colors and models is likely due to limitations in the individual membership catalogs and/or systematic differences in the predicted stellar parameters from the different sets of models. Interestingly, when we compare the isochrone ages for IC4665 to the published lithium depletion boundary age, 28+-5 Myr, we observe that this cluster does not appear to follow the trend of isochrone ages being 1.5 times smaller than lithium depletion boundary ages. In addition, comparing the overall magnetic activity (X-ray and H-alpha emission) in IC4665 with other well studied open clusters, we find the observed activity distributions for this young cluster are best characterized by assuming an age of 30-40 Myr, thus in agreement with our pre-main-sequence and turn-off isochrone ages for IC4665. Overall, although some age discrepancies do exist, particularly in the ages measured from pre-main-sequence isochrones, the range of possible IC4665 ages derived from the various dating techniques employed here is relatively small compared to that found for other well studied open clusters., Comment: 17 pages, 13 figures, 6 tables; Accepted for publication in the Astronomical Journal
- Published
- 2010
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19. Low-mass members of the young cluster IC 4665 and pre-main-sequence lithium depletion
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Phillip Cargile, R. D. Jeffries, R. J. Jackson, and David James
- Subjects
Physics ,endocrine system ,chemistry.chemical_element ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Stellar classification ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,chemistry ,Convection zone ,Space and Planetary Science ,Radiative transfer ,Cluster (physics) ,Lithium ,Spectroscopy ,Low Mass ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We have used fibre spectroscopy to establish cluster membership and examine pre-main-sequence (PMS) lithium depletion for low-mass stars (spectral types F to M) in the sparse young (~30 Myr) cluster IC 4665. We present a filtered candidate list of 40 stars that should contain 75 per cent of single cluster members with V of 11.5 to 18 in the central square degree of the cluster. Whilst F- and G-type stars in IC 4665 have depleted little or no lithium, the K- and early M-type stars have depleted more Li than expected when compared with similar stars in other clusters of known age. An empirical age estimate based on Li-depletion among the late-type stars of IC 4665 would suggest it is older than 100 Myr. This disagrees entirely with ages determined either from the nuclear turn-off, from isochronal matches to low-mass stars or from the re-appearance of lithium previously found in much lower mass stars (the ``lithium depletion boundary''). We suggest that other parameters besides age, perhaps composition or rotation, are very influential in determining the degree of PMS Li-depletion in stars with M greater than 0.5 Msun. Further work is required to identify and assess the effects of these additional parameters, particularly to probe conditions at the interface between the sub-photospheric convection zone and developing radiative core. Until then, PMS Li depletion in F- to early M-type stars cannot be confidently used as a precise age indicator in young clusters, kinematic groups or individual field stars., Comment: Accepted for publication in MNRAS
- Published
- 2009
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20. Surprising dissimilarities in a newly formed pair of 'identical twin' stars
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Eric Stempels, Aaron M. Geller, Keivan G. Stassun, Phillip Cargile, Robert D. Mathieu, and Alicia Aarnio
- Subjects
Physics ,Solar mass ,Multidisciplinary ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Stars ,Primary (astronomy) ,Orion Nebula ,Binary star ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Binary system ,Sibling ,Stellar evolution ,Astrophysics::Galaxy Astrophysics - Abstract
The mass and chemical composition of a star are the primary determinants of its basic physical properties--radius, temperature, luminosity--and how those properties evolve with time. Thus, two stars born at the same time, from the same natal material, and with the same mass are 'identical twins,' and as such might be expected to possess identical physical attributes. We have discovered in the Orion Nebula a pair of stellar twins in a newborn binary star system. Each star in the binary has a mass of 0.41 +/- 0.01 solar masses, identical to within 2 percent. Here we report that these twin stars have surface temperatures that differ by ~300K (~10%), and luminosities that differ by ~50%, both at high confidence level. Preliminary results indicate that the stars' radii also differ, by 5-10%. These surprising dissimilarities suggest that one of the twins may have been delayed by several hundred thousand years in its formation relative to its sibling. Such a delay could only have been detected in a very young, definitively equal-mass binary system3 such as that reported here. Our findings reveal cosmic limits on the age synchronisation of young binary stars, often used as tests for the age calibrations of star-formation models., Comment: Published in Nature, 19 June 2008
- Published
- 2008
21. A New Detached M Dwarf Eclipsing Binary
- Author
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David Charbonneau, Phillip Cargile, D. Kolinski, J. A. Belmonte, O. L. Creevey, Roi Alonso, Barbara McArthur, Francis T. O'Donovan, S. J. Jiménez-Reyes, Georgi Mandushev, Timothy M. Brown, William D. Cochran, and George F Benedict
- Subjects
Physics ,Solar mass ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Solar radius ,Astrophysics ,Light curve ,Orbital inclination ,Radial velocity ,Photometry (optics) ,Amplitude ,Space and Planetary Science ,Binary system - Abstract
We describe a newly-discovered detached M-dwarf eclipsing binary system, the fourth such system known. This system was first observed by the TrES network during a long term photometry campaign of 54 nights. Analysis of the folded light curve indicates two very similar components orbiting each other with a period of 1.12079 +/- 0.00001 days. Spectroscopic observations with the Hobby-Eberly Telescope show the system to consist of two M3e dwarfs in a near-circular orbit. Double-line radial velocity amplitudes, combined with the orbital inclination derived from light-curve fitting, yield Mass total = 0.983 +/- 0.007 solar masses, with component masses M(1) = 0.493 +/- 0.003 and M(2) = 0.489 +/- 0.003 solar masses. The light-curve fit yields component radii of R(1) = 0.453 +/- 0.060 and R(2) = 0.452 +/- 0.050 solar radii. Though a precise parallax is lacking, broadband VJHK colors and spectral typing suggest component absolute magnitudes of M_V(1) = 11.18 +/- 0.30 and M_V(2) = 11.28 +/- 0.30., 15 pages, 3 figure, 3 tables, accepted by ApJL, additional references
- Published
- 2005
22. The Effects of Magnetic Activity on Lithium-Inferred Ages of Stars
- Author
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Phillip Cargile, Aaron J. Juarez, David James, and Keivan G. Stassun
- Subjects
Physics ,T Tauri star ,Stars ,chemistry ,Space and Planetary Science ,chemistry.chemical_element ,Astronomy and Astrophysics ,Lithium ,Astrophysics ,Open cluster - Abstract
In this project, we investigate the effects of magnetic activity on the Lithium Depletion Boundary (LDB) to recalibrate the measured ages for star clusters, using the open cluster Blanco 1 as a pilot study. We apply the LDB technique on low-mass Pre-Main-Sequence (PMS) stars to derive an accurate age for Blanco 1, and we consider the effect of magnetic activity on this inferred age. Although observations have shown that magnetic activity directly affects stellar radius and temperature, most PMS models do not include the effects of magnetic activity on stellar properties. Since the lithium abundance of a star depends on its radius and temperature, we expect that LDB ages are affected by magnetic activity. After empirically accounting for the effects of magnetic activity, we find the age of Blanco 1 to be ~100 Myr, which is ~30 Myr younger than the standard LDB age of ~130 Myr.
- Published
- 2013
23. The HoSTS Project: A Homogeneous Study of Transiting Systems
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Francesca Faedi, Amanda P. Doyle, Yilen Gómez Maqueo Chew, S. C. C. Barros, Luan Ghezzi, Leslie Hebb, Don Pollacco, Barry Smalley, Keivan G. Stassun, Andrew Collier Cameron, and Phillip Cargile
- Subjects
Physics ,Stars ,Space and Planetary Science ,Planet ,Homogeneous ,Astronomy and Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics ,Planetary system ,Astrophysics::Galaxy Astrophysics ,Large sample - Abstract
The Homogeneous Study of Transiting Systems (HoSTS) will derive a consistent and homogeneous set of both the stellar and planetary physical properties for a large sample of bright transiting planetary systems with confirmed planetary masses and measured radii. Our resulting catalogs of the fundamental properties of these bright planets and their host stars will enable us to explore empirical correlations that will lead to a better understanding of planetary formation and evolution. We present our pilot study of the planet-hosting star WASP-13, and the framework of our project which will allow for the identification of true relationships among the physical properties of the systems from any systematics.
- Published
- 2013
24. ACCURATE ATMOSPHERIC PARAMETERS AT MODERATE RESOLUTION USING SPECTRAL INDICES: PRELIMINARY APPLICATION TO THE MARVELS SURVEY
- Author
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Luan Ghezzi, Letícia Dutra-Ferreira, Diego Lorenzo-Oliveira, Gustavo F. Porto de Mello, Basílio X. Santiago, Nathan De Lee, Brian L. Lee, Luiz N. da Costa, Marcio A. G. Maia, Ricardo L. C. Ogando, John P. Wisniewski, Jonay I. González Hernández, Keivan G. Stassun, Scott W. Fleming, Donald P. Schneider, Suvrath Mahadevan, Phillip Cargile, Jian Ge, Joshua Pepper, Ji Wang, and Martin Paegert
- Subjects
Alternative methods ,Physics ,Solar neighborhood ,Validation test ,Resolution (electron density) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Espectros astronômicos ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,fundamental parameters [Stars] ,solar-type [Stars] ,Measure (mathematics) ,Spectral line ,spectroscopic [Techniques] ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics::Solar and Stellar Astrophysics ,Atmosferas estelares ,Astrophysics::Earth and Planetary Astrophysics ,atmospheres [Stars] ,Spectral resolution ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics - Abstract
Studies of Galactic chemical and dynamical evolution in the solar neighborhood depend on the availability of precise atmospheric parameters (Teff, [Fe/H] and log g) for solar-type stars. Many large-scale spectroscopic surveys operate at low to moderate spectral resolution for efficiency in observing large samples, which makes the stellar characterization difficult due to the high degree of blending of spectral features. While most surveys use spectral synthesis, in this work we employ an alternative method based on spectral indices to determine the atmospheric parameters of a sample of nearby FGK dwarfs and subgiants observed by the MARVELS survey at moderate resolving power (R~12,000). We have developed three codes to automatically normalize the observed spectra, measure the equivalent widths of the indices and, through the comparison of those with values calculated with pre-determined calibrations, derive the atmospheric parameters of the stars. The calibrations were built using a sample of 309 stars with precise stellar parameters obtained from the analysis of high-resolution FEROS spectra. A validation test of the method was conducted with a sample of 30 MARVELS targets that also have reliable atmospheric parameters from high-resolution spectroscopic analysis. Our approach was able to recover the parameters within 80 K for Teff, 0.05 dex for [Fe/H] and 0.15 dex for log g, values that are lower or equal to the typical external uncertainties found between different high-resolution analyzes. An additional test was performed with a subsample of 138 stars from the ELODIE stellar library and the literature atmospheric parameters were recovered within 125 K for Teff, 0.10 dex for [Fe/H] and 0.29 dex for log g. These results show that the spectral indices are a competitive tool to characterize stars with the intermediate resolution spectra., Accepted for publication in AJ. Abstract edited to comply with arXiv standards regarding the number of characters
- Published
- 2014
25. ECLIPSING BINARY SCIENCE VIA THE MERGING OF TRANSIT AND DOPPLER EXOPLANET SURVEY DATA—A CASE STUDY WITH THE MARVELS PILOT PROJECT AND SuperWASP
- Author
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Gustavo F. Porto de Mello, Keivan G. Stassun, Bruce L. Gary, Richard G. West, Justin R. Crepp, Scott W. Fleming, Luiz N. da Costa, Julian C. van Eyken, Luan Ghezzi, Ian Skillen, Phillip Cargile, David R. Anderson, Marcio A. G. Maia, Bo Zhao, Xiaoke Wan, Jian Ge, Pierre F. L. Maxted, John P. Wisniewski, Suvrath Mahadevan, P. Guo, Don Pollacco, Stephen R. Kane, Leticia D. Ferreira, Martin Paegert, Brian C. Lee, Nathan De Lee, Leslie Hebb, Coel Hellier, Duy Cuong Nguyen, Basilio X. Santiago, and Andrew Collier Cameron
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,eclipsing [Binaries] ,Eclipses ,FOS: Physical sciences ,Binary number ,Astronomy and Astrophysics ,Astrophysics ,Espectroscopia ,01 natural sciences ,Exoplanet ,Photometry (astronomy) ,Stars ,spectroscopic [Binaries] ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Primary (astronomy) ,Efeito doppler ,0103 physical sciences ,Binary star ,Transit (astronomy) ,010303 astronomy & astrophysics ,Stellar evolution ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences - Abstract
Exoplanet transit and Doppler surveys discover many binary stars during their operation that can be used to conduct a variety of ancillary science. Specifically, eclipsing binary stars can be used to study the stellar mass-radius relationship and to test predictions of theoretical stellar evolution models. By cross-referencing 24 binary stars found in the MARVELS Pilot Project with SuperWASP photometry, we find two new eclipsing binaries, TYC 0272-00458-1 and TYC 1422-01328-1, which we use as case studies to develop a general approach to eclipsing binaries in survey data. TYC 0272-00458-1 is a single-lined spectroscopic binary for which we calculate a mass of the secondary and radii for both components using reasonable constraints on the primary mass through several different techniques. For a primary mass of M_1 = 0.92 +/- 0.1 M_solar, we find M_2 = 0.610 +/- 0.036 M_solar, R_1 = 0.932 +/- 0.076 R_solar and R_2 = 0.559 +/- 0.102 R_solar, and find that both stars have masses and radii consistent with model predictions. TYC 1422-01328-1 is a triple-component system for which we can directly measure the masses and radii of the eclipsing pair. We find that the eclipsing pair consists of an evolved primary star (M_1 = 1.163 +/- 0.034 M_solar, R_1 = 2.063 +/- 0.058 R_solar) and a G-type dwarf secondary (M_2 = 0.905 +/- 0.067 M_solar, R_2 = 0.887 +/- 0.037 R_solar). We provide the framework necessary to apply this analysis to much larger datasets., Comment: Accepted for publication in AJ
- Published
- 2011
26. Precise orbit solution of MML 53, a low-mass, pre-main sequence eclipsing binary in Upper Centaurus Lupus
- Author
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Lauren E. Palladino, H. C. Stempels, Keivan G. Stassun, Heather Cegla, Phillip Cargile, and Leslie Hebb
- Subjects
Orbital elements ,Physics ,Lupus (constellation) ,Astronomy ,Binary number ,Astronomy and Astrophysics ,Astrophysics ,Measure (mathematics) ,Spectral line ,Space and Planetary Science ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Orbit (control theory) ,Low Mass ,Spectrograph - Abstract
Aims. We present a double-lined orbit solution for MML 53, the recently discovered low-mass pre-main sequence eclipsing binary. Methods. Using high-resolution spectra from the SMARTS 1.5 m echelle spectrograph, we measure precise radial velocities and derive the orbital parameters of the system. Results. The 2.1 d orbit of the eclipsing pair is circular, and we find the minimum masses of the eclipsing components to be
- Published
- 2011
27. Erratum: “A Complete Census of Luminous Stellar Variability on Day to Decade Timescales” (2018, ApJ, 864, 111).
- Author
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Charlie Conroy, Jay Strader, Pieter van Dokkum, Andrew E. Dolphin, Daniel R. Weisz, Jeremiah W. Murphy, Aaron Dotter, Benjamin D. Johnson, and Phillip Cargile
- Subjects
CENSUS ,ASYMPTOTIC giant branch stars ,STELLAR populations ,EARLY stars ,VARIABLE stars - Published
- 2020
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28. Resolving the Metallicity Distribution of the Stellar Halo with the H3 Survey.
- Author
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Charlie Conroy, Rohan P. Naidu, Dennis Zaritsky, Ana Bonaca, Phillip Cargile, Benjamin D. Johnson, and Nelson Caldwell
- Subjects
STELLAR orbits ,STELLAR spectra ,PARALLAX ,STELLAR mass ,CHEMICAL properties ,GALACTIC halos ,DWARF galaxies - Abstract
The Galactic stellar halo is predicted to have formed at least partially from the tidal disruption of accreted dwarf galaxies. This assembly history should be detectable in the orbital and chemical properties of stars. The H3 Survey is obtaining spectra for 200,000 stars and, when combined with Gaia data, is providing detailed orbital and chemical properties of Galactic halo stars. Unlike previous surveys of the halo, the H3 target selection is based solely on magnitude and Gaia parallax; the survey therefore provides a nearly unbiased view of the entire stellar halo at high latitudes. In this paper we present the distribution of stellar metallicities as a function of Galactocentric distance and orbital properties for a sample of 4232 kinematically selected halo giants to 100 kpc. The stellar halo is relatively metal-rich, , and there is no discernible metallicity gradient over the range 6 < R
gal < 100 kpc. However, the halo metallicity distribution is highly structured, including distinct metal-rich and metal-poor components at Rgal < 10 kpc and Rgal > 30 kpc, respectively. The Sagittarius stream dominates the metallicity distribution at 20–40 kpc for stars on prograde orbits. The Gaia–Enceladus merger remnant dominates the metallicity distribution for radial orbits to ≈30 kpc. Metal-poor stars with [Fe/H] < −2 are a small population of the halo at all distances and orbital categories. We associate the "in situ" stellar halo with stars displaying thick disk chemistry on halo-like orbits; such stars are confined to . The majority of the stellar halo is resolved into discrete features in chemical–orbital space, suggesting that the bulk of the stellar halo formed from the accretion and tidal disruption of dwarf galaxies. The relatively high metallicity of the halo derived in this work is a consequence of the unbiased selection function of halo stars and, in combination with the recent upward revision of the total stellar halo mass, implies a Galactic halo metallicity that is typical for its mass. [ABSTRACT FROM AUTHOR]- Published
- 2019
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29. A Dynamical Model for Clustered Star Formation in the Galactic Disk.
- Author
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Harshil Kamdar, Charlie Conroy, Yuan-Sen Ting, Ana Bonaca, Benjamin Johnson, and Phillip Cargile
- Subjects
STAR formation ,GALAXY formation ,MOLECULAR clouds ,PHASE space ,DISKS (Astrophysics) - Abstract
The clustered nature of star formation should produce a high degree of structure in the combined phase and chemical space in the Galactic disk. To date, observed structure of this kind has been mostly limited to bound clusters and moving groups. In this paper, we present a new dynamical model of the Galactic disk that takes into account the clustered nature of star formation. This model predicts that the combined phase and chemical space is rich in substructure and that this structure is sensitive to both the precise nature of clustered star formation and the large-scale properties of the Galaxy. The model self-consistently evolves 4 billion stars over the last 5 Gyr in a realistic potential that includes an axisymmetric component, a bar, spiral arms, and giant molecular clouds. All stars are born in clusters with an observationally motivated range of initial conditions. As direct N-body calculations for billions of stars are computationally infeasible, we have developed a method of initializing star cluster particles to mimic the effects of direct N-body effects, while the actual orbit integrations are treated as test particles within the analytic potential. We demonstrate that the combination of chemical and phase space information is much more effective at identifying truly conatal populations than either chemical or phase space alone. Furthermore, we show that comoving pairs of stars are very likely to be conatal if their velocity separation is <2 km s
−1 and their metallicity separation is <0.05 dex. The results presented here bode well for harnessing the synergies between Gaia and spectroscopic surveys to reveal the assembly history of the Galactic disk. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
30. Mapping the Stellar Halo with the H3 Spectroscopic Survey.
- Author
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Charlie Conroy, Ana Bonaca, Phillip Cargile, Benjamin D. Johnson, Nelson Caldwell, Rohan P. Naidu, Dennis Zaritsky, Daniel Fabricant, Sean Moran, Jaehyon Rhee, Andrew Szentgyorgyi, Perry Berlind, Michael L. Calkins, ShiAnne Kattner, and Chun Ly
- Subjects
STELLAR parallax ,GALACTIC halos ,GALAXY formation ,COSMOCHEMISTRY ,PHASE space ,ASTROMETRY - Abstract
Modern theories of galaxy formation predict that the Galactic stellar halo was hierarchically assembled from the accretion and disruption of smaller systems. This hierarchical assembly is expected to produce a high degree of structure in the combined phase and chemistry space; this structure should provide a relatively direct probe of the accretion history of our Galaxy. Revealing this structure requires precise 3D positions (including distances), 3D velocities, and chemistry for large samples of stars. The Gaia satellite is delivering proper motions and parallaxes for >1 billion stars to G ≈ 20. However, radial velocities and metallicities will only be available to G ≈ 15, which is insufficient to probe the outer stellar halo (≳10 kpc). Moreover, parallaxes will not be precise enough to deliver high-quality distances for stars beyond ∼10 kpc. Identifying accreted systems throughout the stellar halo therefore requires a large ground-based spectroscopic survey to complement Gaia. Here we provide an overview of the H3 Stellar Spectroscopic Survey, which will deliver precise stellar parameters and spectrophotometric distances for ≈200,000 stars to r = 18. Spectra are obtained with the Hectochelle instrument at the MMT, which is configured for the H3 Survey to deliver resolution R ≈ 23,000 spectra covering the wavelength range 5150–5300 Å. The survey is optimized for stellar halo science and therefore focuses on high Galactic latitude fields (), sparsely sampling 15,000 sq. degrees. Targets are selected on the basis of Gaia parallaxes, enabling very efficient selection of bona fide halo stars. The survey began in the fall of 2017 and has collected 88,000 spectra to-date. All of the data, including the derived stellar parameters, will eventually be made publicly available via the survey website: h3survey.rc.fas.harvard.edu. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
31. The Payne: Self-consistent ab initio Fitting of Stellar Spectra.
- Author
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Yuan-Sen Ting, Charlie Conroy, Hans-Walter Rix, and Phillip Cargile
- Subjects
STELLAR spectra ,CALIBRATION ,LABELS ,ORBIT determination ,INTERPOLATION - Abstract
We present The Payne, a general method for the precise and simultaneous determination of numerous stellar labels from observed spectra, based on fitting physical spectral models. The Payne combines a number of important methodological aspects: it exploits the information from much of the available spectral range; it fits all labels (stellar parameters and elemental abundances) simultaneously; it uses spectral models, where the structure of the atmosphere and the radiative transport are consistently calculated to reflect the stellar labels. At its core The Payne has an approach to accurate and precise interpolation and prediction of the spectrum in high-dimensional label space that is flexible and robust, yet based on only a moderate number of ab initio models ( for 25 labels). With a simple neural-net-like functional form and a suitable choice of training labels, this interpolation yields a spectral flux prediction good to 10
−3 rms across a wide range of Teff and (including dwarfs and giants). We illustrate the power of this approach by applying it to the APOGEE DR14 data set, drawing on Kurucz models with recently improved line lists: without recalibration, we obtain physically sensible stellar parameters as well as 15 elemental abundances that appear to be more precise than the published APOGEE DR14 values. In short, The Payne is an approach that for the first time combines all these key ingredients, necessary for progress toward optimal modeling of survey spectra; and it leads to both precise and accurate estimates of stellar labels, based on physical models and without “recalibration.” Both the codes and catalog are made publicly available online. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
32. Signatures of unresolved binaries in stellar spectra: implications for spectral fitting
- Author
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Daniel R. Weisz, C. Conroy, Hans-Walter Rix, Yuan-Sen Ting, Kareem El-Badry, Phillip Cargile, Anna-Christina Eilers, and Maria Bergemann
- Subjects
Population ,FOS: Physical sciences ,Binary number ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Astronomical spectroscopy ,Spectral line ,0103 physical sciences ,Binary star ,Astrophysics::Solar and Stellar Astrophysics ,Binary system ,education ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Physics ,education.field_of_study ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Observable ,Astrophysics - Astrophysics of Galaxies ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::Earth and Planetary Astrophysics - Abstract
The observable spectrum of an unresolved binary star system is a superposition of two single-star spectra. Even without a detectable velocity offset between the two stellar components, the combined spectrum of a binary system is in general different from that of either component, and fitting it with single-star models may yield inaccurate stellar parameters and abundances. We perform simple experiments with synthetic spectra to investigate the effect of unresolved main-sequence binaries on spectral fitting, modeling spectra similar to those collected by the APOGEE, GALAH, and LAMOST surveys. We find that fitting unresolved binaries with single-star models introduces systematic biases in the derived stellar parameters and abundances that are modest but certainly not negligible, with typical systematic errors of $300\,\rm K$ in $T_{\rm eff}$, 0.1 dex in $\log g$, and 0.1 dex in $[\rm Fe/H]$ for APOGEE-like spectra of solar-type stars. These biases are smaller for spectra at optical wavelengths than in the near-infrared. We show that biases can be corrected by fitting spectra with a binary model, which adds only two labels to the fit and includes single-star models as a special case. Our model provides a promising new method to constrain the Galactic binary population, including systems with single-epoch spectra and no detectable velocity offset between the two stars., Accept to MNRAS with minor revisions since v1. 7 pages, 5 figures
33. A Complete Census of Luminous Stellar Variability on Day to Decade Timescales.
- Author
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Charlie Conroy, Jay Strader, Pieter van Dokkum, Andrew E. Dolphin, Daniel R. Weisz, Jeremiah W. Murphy, Aaron Dotter, Benjamin D. Johnson, and Phillip Cargile
- Subjects
TIMESCALE number ,STELLAR activity ,SUPERGIANT stars ,EARLY stars - Abstract
Stellar photometric variability offers a novel probe of the interior structure and evolutionary state of stars. Here we present a census of stellar variability on day to decade timescales across the color–magnitude diagram (CMD) for 73,000 stars brighter than M
I,814 = −5 in the Whirlpool Galaxy (M51). Our Cycle 24 Hubble Space Telescope (HST) program acquired V606 - and I814 -band images over 34 epochs spanning 1 year with pseudo-random cadences enabling sensitivity to periods from days to months. We supplement these data with archival V- and I-band HST data obtained in 1995 and 2005, providing sensitivity to variability on decade timescales. At least 50% of stars brighter than MI,814 = −7 show strong evidence for variability within our Cycle 24 data; among stars with the variability fraction rises to ≈100%. Large amplitude variability (>0.3 mag) on decade timescales is restricted to red supergiants (RSGs) and very luminous blue stars. Both populations display fairly smooth variability on month-year timescales. The Cepheid instability strip is clearly visible in our data, although the variability fraction within this region never exceeds ≈10%. The location of variable stars across the CMD broadly agrees with theoretical sources of variability, including the instability strip, RSG pulsational instabilities, long-period fundamental mode pulsations, and radiation-dominated envelopes in massive stars. Our data can be used to place stringent constraints on the precise onset of these various instabilities and their lifetimes and growth rates. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
34. Absence of a Metallicity Effect for Ultra-short-period Planets.
- Author
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Joshua N. Winn, Roberto Sanchis-Ojeda, Leslie Rogers, Erik A. Petigura, Andrew W. Howard, Howard Isaacson, Geoffrey W. Marcy, Kevin C. Schlaufman, Phillip Cargile, and Leslie Hebb
- Published
- 2017
- Full Text
- View/download PDF
35. Prospects for Measuring Abundances of >20 Elements with Low-resolution Stellar Spectra.
- Author
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Yuan-Sen Ting, Charlie Conroy, Hans-Walter Rix, and Phillip Cargile
- Subjects
STELLAR density (Stellar population) ,MILKY Way ,COSMIC abundances ,DATA analysis ,NUCLEOSYNTHESIS - Abstract
Understanding the evolution of the Milky Way calls for the precise abundance determination of many elements in many stars. A common perception is that deriving more than a few elemental abundances ([Fe/H], [α/Fe], perhaps [C/H], [N/H]) requires medium-to-high spectral resolution, R ≳ 10,000, mostly to overcome the effects of line blending. In a recent work, we presented an efficient and practical way to model the full stellar spectrum, even when fitting a large number of stellar labels simultaneously. In this paper, we quantify to what precision the abundances of many different elements can be recovered, as a function of spectroscopic resolution and wavelength range. In the limit of perfect spectral models and spectral normalization, we show that the precision of elemental abundances is nearly independent of resolution, for a fixed exposure time and number of detector pixels; low-resolution spectra simply afford much higher S/N per pixel and generally larger wavelength range in a single setting. We also show that estimates of most stellar labels are not strongly correlated with one another once R ≳ 1000. Modest errors in the line-spread function, as well as small radial velocity errors, do not affect these conclusions, and data-driven models indicate that spectral (continuum) normalization can be achieved well enough in practice. These results, to be confirmed with an analysis of observed low-resolution data, open up new possibilities for the design of large spectroscopic stellar surveys and for the reanalysis of archival low-resolution data sets. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
36. The Influence of Atomic Diffusion on Stellar Ages and Chemical Tagging.
- Author
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Aaron Dotter, Charlie Conroy, Phillip Cargile, and Martin Asplund
- Subjects
STELLAR activity ,DIFFUSION ,SPECTRUM analysis ,GALACTIC dynamics ,RADIATIVE transitions - Abstract
In the era of large stellar spectroscopic surveys, there is an emphasis on deriving not only stellar abundances but also the ages for millions of stars. In the context of Galactic archeology, stellar ages provide a direct probe of the formation history of the Galaxy. We use the stellar evolution code MESA to compute models with atomic diffusion—with and without radiative acceleration—and extra mixing in the surface layers. The extra mixing consists of both density-dependent turbulent mixing and envelope overshoot mixing. Based on these models we argue that it is important to distinguish between initial, bulk abundances (parameters) and current, surface abundances (variables) in the analysis of individual stellar ages. In stars that maintain radiative regions on evolutionary timescales, atomic diffusion modifies the surface abundances. We show that when initial, bulk metallicity is equated with current, surface metallicity in isochrone age analysis, the resulting stellar ages can be systematically overestimated by up to 20%. The change of surface abundances with evolutionary phase also complicates chemical tagging, which is the concept that dispersed star clusters can be identified through unique, high-dimensional chemical signatures. Stars from the same cluster, but in different evolutionary phases, will show different surface abundances. We speculate that calibration of stellar models may allow us to estimate not only stellar ages but also initial abundances for individual stars. In the meantime, analyzing the chemical properties of stars in similar evolutionary phases is essential to minimize the effects of atomic diffusion in the context of chemical tagging. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
37. KELT-17B: A HOT-JUPITER TRANSITING AN A-STAR IN A MISALIGNED ORBIT DETECTED WITH DOPPLER TOMOGRAPHY.
- Author
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George Zhou, Joseph E. Rodriguez, Karen A. Collins, Thomas Beatty, Thomas Oberst, Tyler M. Heintz, Keivan G. Stassun, David W. Latham, Rudolf B. Kuhn, Allyson Bieryla, Michael B. Lund, Jonathan Labadie-Bartz, Robert J. Siverd, Daniel J. Stevens, B. Scott Gaudi, Joshua Pepper, Lars A. Buchhave, Jason Eastman, Knicole Colón, and Phillip Cargile
- Published
- 2016
- Full Text
- View/download PDF
38. DM ORI: A YOUNG STAR OCCULTED BY A DISTURBANCE IN ITS PROTOPLANETARY DISK.
- Author
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Joseph E. Rodriguez, Keivan G. Stassun, Phillip Cargile, Benjamin J. Shappee, Robert J. Siverd, Joshua Pepper, Michael B. Lund, Christopher S. Kochanek, David James, Rudolf B. Kuhn, Thomas G. Beatty, B. Scott Gaudi, David A. Weintraub, Krzysztof Z. Stanek, Thomas W.-S. Holoien, Jose L. Prieto, Daniel M. Feldman, and Catherine C. Espaillat
- Subjects
CIRCUMSTELLAR matter ,PROTOPLANETARY disks ,ORIGIN of planets ,STAR formation ,SPECTRAL energy distribution - Abstract
In some planet formation theories, protoplanets grow gravitationally within a young star’s protoplanetary disk, a signature of which may be a localized disturbance in the disk’s radial and/or vertical structure. Using time-series photometric observations by the Kilodegree Extremely Little Telescope South project and the All-Sky Automated Survey for SuperNovae, combined with archival observations, we present the discovery of two extended dimming events of the young star, DM Ori. This young system faded by ∼1.5 mag from 2000 March to 2002 August and then again in 2013 January until 2014 September (depth ∼1.7 mag). We constrain the duration of the 2000–2002 dimming to be < 860 days, and the event in 2013–2014 to be < 585 days, separated by ∼12.5 years. A model of the spectral energy distribution indicates a large infrared excess consistent with an extensive circumstellar disk. Using basic kinematic arguments, we propose that DM Ori is likely being periodically occulted by a feature (possibly a warp or perturbation) in its circumstellar disk. In this scenario, the occulting feature is located >6 au from the host star, moving at ∼14.6 km s
−1 and is ∼4.9 au in width. This localized structure may indicate a disturbance such as that which may be caused by a protoplanet early in its formation. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
39. V409 TAU AS ANOTHER AA TAU: PHOTOMETRIC OBSERVATIONS OF STELLAR OCCULTATIONS BY THE CIRCUMSTELLAR DISK.
- Author
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Joseph E. Rodriguez, Joshua Pepper, Keivan G. Stassun, Robert J. Siverd, Phillip Cargile, David A. Weintraub, Thomas G. Beatty, B. Scott Gaudi, Eric E. Mamajek, and N. Nicole Sanchez
- Published
- 2015
- Full Text
- View/download PDF
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