References of "Sterken, C"
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See detailSolar-like oscillations in cluster stars
Stello, D.; Basu, S.; Bedding, T. R. et al

in Astronomische Nachrichten (2010), 331

This article summaries a talk given at the HELAS IV international meeting We present a brief overview of the history of attempts to obtain a clear detection of solar-like oscillations in cluster stars ... [more ▼]

This article summaries a talk given at the HELAS IV international meeting We present a brief overview of the history of attempts to obtain a clear detection of solar-like oscillations in cluster stars, and discuss the results on the first clear detection, which was made by the Kepler Asteroseismic Science Consortium (KASC) Working Group 2. Data from Kepler. [less ▲]

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See detailESO Spectrophotometry of Comet 9P/Tempel 1
Weiler, M.; Rauer, H.; Sterken, C. et al

in Käufl, H. U.; Sterken, C. (Eds.) Deep Impact as a World Observatory Event: Synergies in Space, Time, and Wavelength (2009)

The Deep Impact target comet 9P/Tempel 1 was observed by means of long-slit spectroscopy from two nights before impact up to eight nights after impact, using the ESO VLT UT1, UT2, and ESO NTT telescopes ... [more ▼]

The Deep Impact target comet 9P/Tempel 1 was observed by means of long-slit spectroscopy from two nights before impact up to eight nights after impact, using the ESO VLT UT1, UT2, and ESO NTT telescopes. Spectra covering the complete optical wavelength range were obtained, and information at different position angles in the coma was collected. The data were used to study the gas and dust activity of comet 9P/Tempel 1. Gas production rates before and after impact and the amount of material in the impact cloud were determined. The pre-impact Afρ parameter, the dust production rate and the dust-to-gas mass ratio were derived. A variation of the cometary gas activity with rotation of the nucleus was detected. A difference in the variation of the brightness of the CN gas emission band compared to the variation of the emissions by C_2, C_3, and NH_2 in the inner coma suggests compositional differences between different parts of the surface of comet 9P/Tempel 1's nucleus. [less ▲]

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See detailDynamical Modeling of the Deep Impact Dust Ejecta Cloud
Bonev, T.; Ageorges, N.; Bagnulo, S. et al

in Käufl, H. U.; Sterken, C. (Eds.) Deep Impact as a World Observatory Event: Synergies in Space, Time, and Wavelength (2009)

The collision of Deep Impact with comet 9P/Tempel 1 generated a bright cloud of dust which dissipated during several days after the impact. The brightness variations of this cloud and the changes of its ... [more ▼]

The collision of Deep Impact with comet 9P/Tempel 1 generated a bright cloud of dust which dissipated during several days after the impact. The brightness variations of this cloud and the changes of its position and shape are governed by the physical properties of the dust grains. We use a Monte Carlo model to describe the evolution of the post-impact dust plume. The results of our dynamical simulations are compared to the data obtained with FORS2footnote{FORS stands for \underline{FO}cal Reducer and low dispersion Spectrograph for the Very Large Telescope (VLT) of the European Southern Observatory (ESO).} to derive the particle size distribution and the total amount of material contained in the dust ejecta cloud. [less ▲]

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See detailThe Dusty View of DI from ESO Chile
Boehnhardt, H.; Ageorges, N.; Bagnulo, S. et al

in Käufk, H. U.; Sterken, C. (Eds.) Deep Impact as a World Observatory Event: Synergies in Space, Time, and Wavelength (2009)

Around the time of the impact of NASA's Deep Impact (DI) mission at comet 9P/Tempel 1, in total 6 telescopes with altogether 7 different instruments, located at the La Silla (LSO) and Paranal (VLT ... [more ▼]

Around the time of the impact of NASA's Deep Impact (DI) mission at comet 9P/Tempel 1, in total 6 telescopes with altogether 7 different instruments, located at the La Silla (LSO) and Paranal (VLT) Observatories of the European Southern Observatory (ESO) in Chile, were used to characterize the dust properties before and after the event. The ejecta cloud expanded at an average speed of about 200 ms[SUP]-1[/SUP]during the first hours after the event. It reached stagnation distance of 25000 km about 3 days after impact. The pre-impact dust jet and fan activity (`porcupine' pattern) remained undisturbed after impact. In our measurements the jet activity can be traced to a few 100 km nucleus distance. In total 9 comastructures are identified which may originate from at least 4 regions of enhanced dust emission on the nucleus - one of this region may in fact be multiple. No obvious signatures of a new active region created by DI are found. The overall dust production during the impact compares to about 5-10 h of normal activity. The global expansion geometry of the DI cloud is compatible with a majority of dust grains in the micron size range. Indications exist for asymmetric brightness and colour distributions of the dust in the ejecta cloud. The dust temperature rose from about 280-290 K before to 330 K one day after the event and fell to pre-impact level the day thereafter. The dust reflected sunlight was found to be linearly polarized at about 7.5% in the visible and near-IR, at constant level within about 4000 km from the nucleus. No circular polarization of the dust is detected. [less ▲]

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See detailObservations of CN and dust activity of comet 9P/Tempel 1 around Deep Impact
Rauer, H.; Weiler, M.; Sterken, C. et al

in Astronomy and Astrophysics (2006), 459

Aims.We present observations of CN emission and the scattered solar light on cometary dust particles around the impact time of the Deep Space spacecraft (NASA) into the nucleus of comet 9P/Tempel 1. The ... [more ▼]

Aims.We present observations of CN emission and the scattered solar light on cometary dust particles around the impact time of the Deep Space spacecraft (NASA) into the nucleus of comet 9P/Tempel 1. The purpose of the observations was to compare post-impact activity to the conditions pre-impact to search for new spectral emission lines after impact, to quantify the increase in gas activity due to the impact and to study the long-term activity changes.<BR /> Methods: .We performed long-slit spectroscopy observations of comet 9P/Tempel 1 at the VLT, ESO, using the FORS instruments from July 2 to July 12, 2005. A wavelengths range of 370-920 nm was covered using two grisms. Four different position angle settings of the slit were applied each night with the projected Sun-comet line as standard setting, for which we report results here.<BR /> Results: .The optical spectra of comet 9P/Tempel 1 showed the usual emission bands in the optical wavelengths range of the radicals: CN, C3, C2 and NH2. No new emission bands were detected after impact. The ejecta cloud of gas and dust caused by the impacting spacecraft into the cometary nucleus could be followed over the observing period. The projected expansion velocities have been determined. The night after impact we observed about (3.9 ± 1.2) × 10[SUP]29[/SUP] molecules of the CN parent in the ejected cloud. However, after five days the appearance of the gas and dust coma was back to pre-impact conditions. <BR /> [less ▲]

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See detailDeep Impact: Observations from a Worldwide Earth-Based Campaign
Meech, K. J.; Ageorges, N.; A'Hearn, M. F. et al

in Science (2005), 310

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign ... [more ▼]

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics. [less ▲]

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See detailThe deep impact campaign at ESO: the gas component
Rauer, H.; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

Poster (2005)

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See detailThe onset of photometric variability in red giant stars.
Jorissen, A.; Mowlavi, N.; Sterken, C. et al

in Astronomy and Astrophysics (1997), 324

The onset of variability in red giant stars is studied from the data collected by the `Long-Term Photometry of Variables' project which operates at ESO (La Silla) since 1982. The differential nature of ... [more ▼]

The onset of variability in red giant stars is studied from the data collected by the `Long-Term Photometry of Variables' project which operates at ESO (La Silla) since 1982. The differential nature of the observations combined with a multi-night reduction algorithm enables to study the variability of over 50 red giants with an accuracy of the order of 2 to 3 millimagnitudes on time scales ranging from days to years. All red giants with spectral types late G to early K (i.e. b-y~0.6-0.8) are stable at the level Ï _y_<6millimag (where Ï _y_ is the standard deviation of the Stroemgren y magnitude). Red giants with later spectral types are all variable, and it is found that the minimum variability level Ï _y, min_ increases with increasing b-y, thus defining a minimum-variability boundary. The new data obtained in this paper reveal that the time scale of the associated variability increases with increasing b-y (and thus amplitude), and that the stability of this time scale improves concomitantly. More precisely, irregular variations on time scales of 5 to 10-days (and Ï _y_~7millimag) characterize red giants with b-y~1.0, whereas the variations (with Ï _y_~100millimag) become more regular with periods of the order of 50d for red giants with b-y~1.3. A radial-velocity jitter (of the order of 1.5km/s r.m.s.) is associated with this photometric variability, and suggests that stellar oscillations may be responsible for the observed variations. [less ▲]

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See detailLong-term photometry of Variables IV (Sterken+, 1995)
Sterken, C.; Manfroid, Jean ULg; Beele, D. et al

Report (1996)

This is the fourth catalogue of photometric data in the Stroemgren system obtained during the period June 18, 1992 - August 23, 1994 in the framework of the Long-Term Photometry of Variables (LTPV ... [more ▼]

This is the fourth catalogue of photometric data in the Stroemgren system obtained during the period June 18, 1992 - August 23, 1994 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. Since our goal is not absolute (all-sky) photometry, the observations should be used for differential photometry only. The mean values of the r.m.s. deviations of the differential measurements of comparison stars are around (from Table 3 of paper) ------------------------------ y b-y m1 c1 ------------------------------ 0.005 0.002 0.004 0.007 ------------------------------ (2 data files). [less ▲]

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See detailThe enigmatic flarings of HR2517.
Sterken, C.; Manfroid, Jean ULg

in Astronomy and Astrophysics (1996), 305

We report the discovery of strong flaring of the B3 II-III star HR2517. The evidence is based on Stroemgren differential uvby photometry spanning more than a decade. We discuss the behaviour of HR2517 in ... [more ▼]

We report the discovery of strong flaring of the B3 II-III star HR2517. The evidence is based on Stroemgren differential uvby photometry spanning more than a decade. We discuss the behaviour of HR2517 in terms of two models, viz. a rooted bright spot suddenly appearing and developing with modulation in photospheric temperature producing periodic light and profile variations as the star rotates, or that HR2517 is a Be star in an eccentric (P~33-34d) high-mass X-ray binary (HMXB) with neutron star companion--one of the brightest such systems known. [less ▲]

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See detailLong-term photometry of Variables III (Manfroid+, 1995)
Manfroid, Jean ULg; Sterken, C.; Cunow, B. et al

Report (1995)

This is the third catalogue of photometric data in the Stroemgren system obtained during the period October 1990-January 1992 in the framework of the Long-Term Photometry of Variables (LTPV) program at ... [more ▼]

This is the third catalogue of photometric data in the Stroemgren system obtained during the period October 1990-January 1992 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. All data have been obtained with the Danish 50-cm telescope. The mean values of the r.m.s. deviations of the differential measurements of comparison stars are around (from Table 4 of paper) ------------------------------ y b-y m1 c1 ------------------------------ 0.005 0.002 0.004 0.006 ------------------------------ (2 data files). [less ▲]

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See detailLong-term photometry of Variables I. (Manfroid+ 1991)
Manfroid, Jean ULg; Sterken, C.; Bruch, A. et al

Report (1995)

This is the first catalogue of photometric data in the Stroemgren system obtained during the period October 1982 - September 1986. Full description can be found in ESO report SP 8. Since our goal is not ... [more ▼]

This is the first catalogue of photometric data in the Stroemgren system obtained during the period October 1982 - September 1986. Full description can be found in ESO report SP 8. Since our goal is not absolute (all-sky) photometry, the observations should be used for differential photometry only. The mean values of the r.m.s. deviations of the differential measurements of comparison stars are around (from Table 5 of paper) ------------------------------------ System y b-y m1 c1 ------------------------------------ 1 0.0109 0.0088 0.0133 0.0136 4 0.0068 0.0057 0.0079 0.0118 5 0.0087 0.0070 0.0114 0.0114 6 0.0090 0.0078 0.0126 0.0132 7 0.0071 0.0033 0.0041 0.0065 ------------------------------------ (2 data files). [less ▲]

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See detailLong-term photometry of variables at ESO. IV. The fourth data catalogue (1992-1994).
Sterken, C.; Manfroid, Jean ULg; Beele, D. et al

in Astronomy and Astrophysics. Supplement Series (1995), 113

In this paper we present the fourth catalogue of photometric data in the Stroemgren system obtained during the period June 18, 1992-August 23, 1994 in the framework of the Long-Term Photometry of ... [more ▼]

In this paper we present the fourth catalogue of photometric data in the Stroemgren system obtained during the period June 18, 1992-August 23, 1994 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. The catalogue is available in computer readable form at the Centre de Donnees de Strasbourg via anonymous ftp 130.79.128.5. [less ▲]

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See detailFourth Catalogue of Stars Measured in the Long-Term Photometry of Variables Project (1992 - 1994).
Sterken, C.; Manfroid, Jean ULg; Beele, D. et al

in Fourth Catalogue of Stars Measured in the Long-Term Photometry of Variables Project (1992 - 1994)., by Sterken, C.; Manfroid, J.; Beele, D.; de Koff, S.; Eggenkamp, I. M. M. G.; Göcking, K.; Jorissen, A.; Kaufer, A.; Kuss, C.; Schoenmakers, A. P.; Stil, J. M.; van Loon, J.; Vink, J.; Vrielmann, S.; Wälde, E.. European Southern Observatory, Garching (Germany), Apr 1995, 198 p., (1995)

In this catalogue the authors present the photometric data in the Strömgren photometric system obtained during the period June 18, 1992 - August 23, 1994 in the framework of the Long-Term Photometry of ... [more ▼]

In this catalogue the authors present the photometric data in the Strömgren photometric system obtained during the period June 18, 1992 - August 23, 1994 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. The catalogue is available in computer readable form at the Centre de Données de Strasbourg. [less ▲]

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See detailLong-term photometry of variables at ESO. III. The third data catalogue (1990-1992).
Manfroid, Jean ULg; Sterken, C.; Cunow, B. et al

in Astronomy and Astrophysics. Supplement Series (1995), 109

In this paper we present the third catalogue of photometric data in the Stroemgren system obtained during the period October 1990-January 1992 in the framework of the Long-Term Photometry of Variables ... [more ▼]

In this paper we present the third catalogue of photometric data in the Stroemgren system obtained during the period October 1990-January 1992 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. The catalogue is available in computer readable form at the Centre de Donnees de Strasbourg. [less ▲]

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See detail1995, Fourth Catalogue of stars measured in the Long-Term Photometry of Variables project.
Sterken, C.; Manfroid, Jean ULg; Beele, D. et al

Book published by ESO (1995)

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See detailA flare event on HR2517
Sterken, C.; Manfroid, Jean ULg

in Information Bulletin on Variable Stars (1994), 4120

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See detailPhotometric monitoring of Wolf-Rayet stars: Strömgren uvby and narrow-band photometry
Gosset, Eric ULg; Rauw, Grégor ULg; Manfroid, Jean ULg et al

in NATO ASIC Proc. 436: The Impact of Long-Term Monitoring on Variable Star Research: Astrophysics (1994)

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See detailThird Catalogue of stars measured in the Long-Term Photometry of Variables project.
Manfroid, Jean ULg; Sterken, C.; Cunow, B. et al

in European Southern Observatory Scientific Report (1994), 14

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