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Caltech Authors (169.770 recursos)

Repository of works by Caltech published authors.

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Mostrando recursos 181 - 200 de 281

  1. Tracing the Orphan Stream to 55 kpc with RR Lyrae Stars

    Sesar, Branimir; Grillmair, Carl J.; Cohen, Judith G.; Bellm, Eric C.; Bhalerao, Varun B.; Levitan, David; Laher, Russ R.; Ofek, Eran O.; Surace, Jason A.; Tang, Sumin; Waszczak, Adam; Kulkarni, Shrinivas R.; Prince, Thomas A.
    We report positions, velocities and metallicities of 50 ab-type RR Lyrae (RRab) stars observed in the vicinity of the Orphan stellar stream. Using about 30 RRab stars classified as being likely members of the Orphan stream, we study the metallicity and the spatial extent of the stream. We find that RRab stars in the Orphan stream have a wide range of metallicities, from -1.5 dex to -2.7 dex. The average metallicity of the stream is -2.1 dex, identical to the value obtained by Newberg et al. (2010) using blue horizontal branch stars. We find that the most distant parts of the stream (40-50 kpc from the...

  2. Discovery, Progenitor and Early Evolution of a Stripped Envelope Supernova iPTF13bvn

    Cao, Yi; Horesh, Assaf; Kulkarni, S. R.; Carpenter, John; Surace, Jason; Masci, Frank; Gelino, Christopher R.; Kasliwal, M. M.
    The intermediate Palomar Transient Factory reports our discovery of a young supernova, iPTF13bvn, in the nearby galaxy, NGC 5806 (22.5 Mpc). Our spectral sequence in the optical and infrared suggests a Type Ib classification. We identify a blue progenitor candidate in deep pre-explosion imaging within a 2σ error circle of 80 mas (8.7 pc). The candidate has an M_B luminosity of −5.52 ± 0.39 mag and a B − I color of 0.25 ± 0.25 mag. If confirmed by future observations, this would be the first direct detection for a progenitor of a Type Ib. Fitting a power law to the early...

  3. Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

    Silverman, Jeffrey M.; Cao, Yi; Horesh, Assaf; Kulkarni, Shrinivas R.; Kasliwal, M. M.
    Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well studied previously, three were previously known but are analyzed...

  4. Centaurs and Scattered Disk Objects in the Thermal Infrared: Analysis of WISE/NEOWISE Observations

    Bauer, James M.; Grav, Tommy; Blauvelt, Erin; Mainzer, A. K.; Masiero, Joseph R.; Stevenson, Rachel; Kramer, Emily; Fernández, Yan R.; Lisse, C. M.; Cutri, Roc M.; Weissman, Paul R.; Dailey, John W.; Masci, Frank J.; Walker, Russell; Waszczak, Adam; Nugent, Carrie R.; Meech, Karen J.; Lucas, Andrew; Pearman, George; Wilkins, Ashlee; Watkins, Jessica; Kulkarni, Shrinivas R.; Wright, Edward L.
    The Wide-field Infrared Survey Explorer (WISE) observed 52 Centaurs and scattered disk objects (SDOs) in the thermal infrared, including 15 new discoveries. We present analyses of these observations to estimate sizes and mean optical albedos. We find mean albedos of 0.08 ± 0.04 for the entire data set. Thermal fits yield average beaming parameters of 0.9 ± 0.2 that are similar for both SDO and Centaur sub-classes. Biased cumulative size distributions yield size-frequency distribution power law indices of ~–1.7 ± 0.3. The data also reveal a relation between albedo and color at the 3σ level. No significant relation between diameter...

  5. Main-belt comets in the Palomar Transient Factory survey – I. The search for extendedness

    Waszczak, A.; Ofek, E. O.; Aharonson, O.; Kulkarni, S. R.; Polishook, D.; Bauer, J. M.; Levitan, D.; Sesar, B.; Laher, R.; Surace, J.
    Cometary activity in main-belt asteroids probes the ice content of these objects and provides clues to the history of volatiles in the inner Solar system. We search the Palomar Transient Factory survey to derive upper limits on the population size of active main-belt comets (MBCs). From data collected from 2009 March through 2012 July, we extracted ∼2 million observations of ∼220 thousand known main-belt objects (40 per cent of the known population, down to ∼1-km diameter) and discovered 626 new objects in multinight linked detections. We formally quantify the ‘extendedness’ of a small-body observation, account for systematic variation in this...

  6. Main-belt comets in the Palomar Transient Factory survey – I. The search for extendedness

    Waszczak, A.; Ofek, E. O.; Aharonson, O.; Kulkarni, S. R.; Polishook, D.; Bauer, J. M.; Levitan, D.; Sesar, B.; Laher, R.; Surace, J.
    Cometary activity in main-belt asteroids probes the ice content of these objects and provides clues to the history of volatiles in the inner Solar system. We search the Palomar Transient Factory survey to derive upper limits on the population size of active main-belt comets (MBCs). From data collected from 2009 March through 2012 July, we extracted ∼2 million observations of ∼220 thousand known main-belt objects (40 per cent of the known population, down to ∼1-km diameter) and discovered 626 new objects in multinight linked detections. We formally quantify the ‘extendedness’ of a small-body observation, account for systematic variation in this...

  7. Discovery of a Cosmological, Relativistic Outburst via its Rapidly Fading Optical Emission

    Cenko, S. Bradley; Kulkarni, S. R.; Horesh, Assaf; Corsi, Alessandra; Carpenter, John; Perley, Daniel A.; Groot, Paul J.; Hallinan, G.; Sesar, Branimir; Kasliwal, M. M.
    We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R_peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g' – R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection...

  8. Discovery of a Cosmological, Relativistic Outburst via its Rapidly Fading Optical Emission

    Cenko, S. Bradley; Kulkarni, S. R.; Horesh, Assaf; Corsi, Alessandra; Carpenter, John; Perley, Daniel A.; Groot, Paul J.; Hallinan, G.; Sesar, Branimir; Kasliwal, M. M.
    We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R_peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g' – R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection...

  9. The UV/optical spectra of the Type Ia supernova SN 2010jn: a bright supernova with outer layers rich in iron-group elements

    Hachinger, S.; Mazzali, P. A.; Sullivan, M.; Ellis, R. S.; Maguire, K.; Gal-Yam, A.; Howell, D. A.; Nugent, P. E.; Baron, E.; Cooke, J.; Arcavi, I.; Bersier, D.; Dilday, B.; James, P. A.; Kasliwal, M. M.; Kulkarni, S. R.; Ofek, E. O.; Laher, R. R.; Parrent, J.; Surace, J.; Yaron, O.; Walker, E. S.
    Radiative transfer studies of Type Ia supernovae (SNe Ia) hold the promise of constraining both the density profile of the SN ejecta and its stratification by element abundance which, in turn, may discriminate between different explosion mechanisms and progenitor classes. Here we analyse the Type Ia SN 2010jn (PTF10ygu) in detail, presenting and evaluating near-ultraviolet (near-UV) spectra from the Hubble Space Telescope and ground-based optical spectra and light curves. SN 2010jn was discovered by the Palomar Transient Factory (PTF) 15 d before maximum light, allowing us to secure a time series of four near-UV spectra at epochs from −10.5 to +4.8 d relative to B-band...

  10. The UV/optical spectra of the Type Ia supernova SN 2010jn: a bright supernova with outer layers rich in iron-group elements

    Hachinger, S.; Mazzali, P. A.; Sullivan, M.; Ellis, R. S.; Maguire, K.; Gal-Yam, A.; Howell, D. A.; Nugent, P. E.; Baron, E.; Cooke, J.; Arcavi, I.; Bersier, D.; Dilday, B.; James, P. A.; Kasliwal, M. M.; Kulkarni, S. R.; Ofek, E. O.; Laher, R. R.; Parrent, J.; Surace, J.; Yaron, O.; Walker, E. S.
    Radiative transfer studies of Type Ia supernovae (SNe Ia) hold the promise of constraining both the density profile of the SN ejecta and its stratification by element abundance which, in turn, may discriminate between different explosion mechanisms and progenitor classes. Here we analyse the Type Ia SN 2010jn (PTF10ygu) in detail, presenting and evaluating near-ultraviolet (near-UV) spectra from the Hubble Space Telescope and ground-based optical spectra and light curves. SN 2010jn was discovered by the Palomar Transient Factory (PTF) 15 d before maximum light, allowing us to secure a time series of four near-UV spectra at epochs from −10.5 to +4.8 d relative to B-band...

  11. Five new outbursting AM CVn systems discovered by the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Simonian, Gregory V.; Arcavi, Iair; Bloom, Joshua S.; Laher, Russ; Nugent, Peter E.; Ofek, Eran O.; Sesar, Branimir; Surace, Jason
    We present five new outbursting AM CVn systems and one candidate discovered as part of an ongoing search for such systems using the Palomar Transient Factory (PTF). This is the first large-area, systematic search for AM CVn systems using only large-amplitude photometric variability to select candidates. Three of the confirmed systems and the candidate system were discovered as part of the PTF transient search. Two systems were found as part of a search for outbursts through the PTF photometric data base. We discuss the observed characteristics of each of these systems, including the orbital periods of two systems. We also...

  12. Five new outbursting AM CVn systems discovered by the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Simonian, Gregory V.; Arcavi, Iair; Bloom, Joshua S.; Laher, Russ; Nugent, Peter E.; Ofek, Eran O.; Sesar, Branimir; Surace, Jason
    We present five new outbursting AM CVn systems and one candidate discovered as part of an ongoing search for such systems using the Palomar Transient Factory (PTF). This is the first large-area, systematic search for AM CVn systems using only large-amplitude photometric variability to select candidates. Three of the confirmed systems and the candidate system were discovered as part of the PTF transient search. Two systems were found as part of a search for outbursts through the PTF photometric data base. We discuss the observed characteristics of each of these systems, including the orbital periods of two systems. We also...

  13. Five new outbursting AM CVn systems discovered by the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Simonian, Gregory V.; Arcavi, Iair; Bloom, Joshua S.; Laher, Russ; Nugent, Peter E.; Ofek, Eran O.; Sesar, Branimir; Surace, Jason
    We present five new outbursting AM CVn systems and one candidate discovered as part of an ongoing search for such systems using the Palomar Transient Factory (PTF). This is the first large-area, systematic search for AM CVn systems using only large-amplitude photometric variability to select candidates. Three of the confirmed systems and the candidate system were discovered as part of the PTF transient search. Two systems were found as part of a search for outbursts through the PTF photometric data base. We discuss the observed characteristics of each of these systems, including the orbital periods of two systems. We also...

  14. Five new outbursting AM CVn systems discovered by the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Simonian, Gregory V.; Arcavi, Iair; Bloom, Joshua S.; Laher, Russ; Nugent, Peter E.; Ofek, Eran O.; Sesar, Branimir; Surace, Jason
    We present five new outbursting AM CVn systems and one candidate discovered as part of an ongoing search for such systems using the Palomar Transient Factory (PTF). This is the first large-area, systematic search for AM CVn systems using only large-amplitude photometric variability to select candidates. Three of the confirmed systems and the candidate system were discovered as part of the PTF transient search. Two systems were found as part of a search for outbursts through the PTF photometric data base. We discuss the observed characteristics of each of these systems, including the orbital periods of two systems. We also...

  15. Disk-related Bursts and Fades in Young Stars

    Findeisen, Krzysztof; Hillenbrand, Lynne; Ofek, Eran; Levitan, David; Sesar, Branimir; Laher, Russ; Surace, Jason
    We present first results from a new, multiyear, time domain survey of young stars in the North America Nebula complex using the Palomar Transient Factory. Our survey is providing an unprecedented view of aperiodic variability in young stars on timescales of days to years. The analyzed sample covers R_(PTF) ≈ 13.5-18 and spans a range of mid-infrared color, with larger-amplitude optical variables (exceeding 0.4 mag root mean squared) more likely to have mid-infrared evidence for circumstellar material. This paper characterizes infrared excess stars with distinct bursts above or fades below a baseline of lower-level variability, identifying 41 examples. The light...

  16. R Coronae Borealis Stars in M31 from the Palomar Transient Factory

    Tang, Sumin; Cao, Yi; Bildsten, Lars; Nugent, Peter; Bellm, Eric; Kulkarni, Shrinivas R.; Laher, Russ; Levitan, David; Masci, Frank; Ofek, Eran O.; Prince, Thomas A.; Sesar, Branimir; Surace, Jason
    We report the discovery of R Coronae Borealis (RCB) stars in the Andromeda galaxy (M31) using the Palomar Transient Factory (PTF). RCB stars are rare hydrogen-deficient, carbon-rich supergiant variables, most likely the merger products of two white dwarfs. These new RCBs, including two confirmed ones and two candidates, are the first to be found beyond the Milky Way and the Magellanic Clouds. All of M31 RCBs showed >1.5 mag irregular declines over timescales of weeks to months. Due to the limiting magnitude of our data (R ≈ 21-22 mag), these RCB stars have R ≈ 19.5-20.5 mag at maximum light,...

  17. R Coronae Borealis Stars in M31 from the Palomar Transient Factory

    Tang, Sumin; Cao, Yi; Bildsten, Lars; Nugent, Peter; Bellm, Eric; Kulkarni, Shrinivas R.; Laher, Russ; Levitan, David; Masci, Frank; Ofek, Eran O.; Prince, Thomas A.; Sesar, Branimir; Surace, Jason
    We report the discovery of R Coronae Borealis (RCB) stars in the Andromeda galaxy (M31) using the Palomar Transient Factory (PTF). RCB stars are rare hydrogen-deficient, carbon-rich supergiant variables, most likely the merger products of two white dwarfs. These new RCBs, including two confirmed ones and two candidates, are the first to be found beyond the Milky Way and the Magellanic Clouds. All of M31 RCBs showed >1.5 mag irregular declines over timescales of weeks to months. Due to the limiting magnitude of our data (R ≈ 21-22 mag), these RCB stars have R ≈ 19.5-20.5 mag at maximum light,...

  18. R Coronae Borealis Stars in M31 from the Palomar Transient Factory

    Tang, Sumin; Cao, Yi; Bildsten, Lars; Nugent, Peter; Bellm, Eric; Kulkarni, Shrinivas R.; Laher, Russ; Levitan, David; Masci, Frank; Ofek, Eran O.; Prince, Thomas A.; Sesar, Branimir; Surace, Jason
    We report the discovery of R Coronae Borealis (RCB) stars in the Andromeda galaxy (M31) using the Palomar Transient Factory (PTF). RCB stars are rare hydrogen-deficient, carbon-rich supergiant variables, most likely the merger products of two white dwarfs. These new RCBs, including two confirmed ones and two candidates, are the first to be found beyond the Milky Way and the Magellanic Clouds. All of M31 RCBs showed >1.5 mag irregular declines over timescales of weeks to months. Due to the limiting magnitude of our data (R ≈ 21-22 mag), these RCB stars have R ≈ 19.5-20.5 mag at maximum light,...

  19. An outburst from a massive star 40 days before a supernova explosion

    Ofek, E. O.; Sullivan, M.; Cenko, S. B.; Kasliwal, M. M.; Gal-Yam, A.; Kulkarni, S. R.; Arcavi, I.; Bildsten, L.; Bloom, J. S.; Horesh, A.; Howell, D. A.; Filippenko, A. V.; Laher, R.; Murray, D.; Nakar, E.; Nugent, P. E.; Silverman, J. M.; Shaviv, N. J.; Surace, J.; Yaron, O.
    Some observations suggest that very massive stars experience extreme mass-loss episodes shortly before they explode as supernovae, as do several models. Establishing a causal connection between these mass-loss episodes and the final explosion would provide a novel way to study pre-supernova massive-star evolution. Here we report observations of a mass-loss event detected 40 days before the explosion of the type IIn supernova SN 2010mc (also known as PTF 10tel). Our photometric and spectroscopic data suggest that this event is a result of an energetic outburst, radiating at least 6 × 10^(47) erg of energy and releasing about 10^(−2) solar masses of material at typical velocities of 2,000 km s^(−1)....

  20. An outburst from a massive star 40 days before a supernova explosion

    Ofek, E. O.; Sullivan, M.; Cenko, S. B.; Kasliwal, M. M.; Gal-Yam, A.; Kulkarni, S. R.; Arcavi, I.; Bildsten, L.; Bloom, J. S.; Horesh, A.; Howell, D. A.; Filippenko, A. V.; Laher, R.; Murray, D.; Nakar, E.; Nugent, P. E.; Silverman, J. M.; Shaviv, N. J.; Surace, J.; Yaron, O.
    Some observations suggest that very massive stars experience extreme mass-loss episodes shortly before they explode as supernovae, as do several models. Establishing a causal connection between these mass-loss episodes and the final explosion would provide a novel way to study pre-supernova massive-star evolution. Here we report observations of a mass-loss event detected 40 days before the explosion of the type IIn supernova SN 2010mc (also known as PTF 10tel). Our photometric and spectroscopic data suggest that this event is a result of an energetic outburst, radiating at least 6 × 10^(47) erg of energy and releasing about 10^(−2) solar masses of material at typical velocities of 2,000 km s^(−1)....

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