The B0.5IVe CoRoT target HD 49330. I. Photometric analysis from CoRoT data

2009

International audience; Context: Be stars undergo outbursts producing a circumstellar disk from the ejected material. The beating of non-radial pulsations has been put forward as a possible mechanism of ejection. Aims: We analyze the pulsational behavior of the early B0.5IVe star HD 49330 observed during the first CoRoT long run towards the Galactical anticenter (LRA1). This Be star is located close to the lower edge of the beta Cephei instability strip in the HR diagram and showed a 0.03 mag outburst during the CoRoT observations. It is thus an ideal case for testing the aforementioned hypothesis. Methods: We analyze the CoRoT light curve of HD 49330 using Fourier methods and non-linear le…

The B0.5 IVe CoRoT target HD 49330. II. Spectroscopic ground-based observations

2009

International audience; Context: We present spectroscopic ground-based observations of the early Be star HD 49330 obtained simultaneously with the CoRoT-LRA1 run just before the burst observed in the CoRoT data. Aims: Ground-based spectroscopic observations of the early Be star HD 49330 obtained during the precursor phase and just before the start of an outburst allow us to disantangle stellar and circumstellar contributions and identify modes of stellar pulsations in this rapidly rotating star. Methods: Time series analysis (TSA) is performed on photospheric line profiles of He I and Si III by means of the least squares method. Results: We find two main frequencies f1 = 11.86 c d-1 and f2 …

Legri Science Operation Center. Architecture and Operations

2001

The LEGRI Science Operation Center (SOC) is the single contact point between the MINISAT-01 Centro de Operaciones Cientificas (COC) located at Villafranca del Castillo (Madrid) and the LEGRI Consortium. Its architecture, operational procedures and associated software has been developed at the Universities of Valencia and Birmingham on the scope to define a integrated Data Analysis System, able to perform the daily follow-up of the instrument health, raw data files decompression and archiving activities (on-line and historical). Pointing and telecommand files generation are also SOC responsibilities. The aim of this paper is to report the SOC activities during the two years of LEGRI operatio…

Four colour photometry of late-type binary systems

1997

This paper presents rst complete uvby light curves of the late-type detached eclipsing binary ZZ UMa (G0V + G8V, P =2 : d 2993). This binary system has been observed during eight campaigns at the Calar Alto Observatory (Almeria, Spain)and at the Sierra Nevada Observatory (Granada, Spain). 294 points distributed over the binary period and covering both eclipses are given. The comparison stars used to calculate the dierential light curves (SAO 15242 and SAO 15251) were conrmed as being good reference stars with constant flux. These observations are part of a 6 year uvby and H monitor- ing program of low mass eclipsing binaries whose main objective is to provide accurate absolute astrophysical…

Activity from the Be/X-ray binary system V0332+53 during its intermediate-luminosity outburst in 2008

2015

Aims: We present a study of the Be/X-ray binary system V 0332+53 with the main goal of characterizing its behavior mainly during the intermediate-luminosity X-ray event on 2008. In addition, we aim to contribute to the understanding of the global behavior of the donor companion by including optical data from our dedicated campaign starting on 2006. Methods: V 0332+53 was observed by RXTE and Swift during the decay of the intermediate-luminosity X-ray outburst of 2008, as well as with Suzaku before the rising of the third normal outburst of the 2010 series. In addition, we present recent data from the Spanish ground-based astronomical observatories of El Teide (Tenerife), Roque de los Muchac…

Four colour photometry of late-type binary systems

1997

This paper presents new complete uvby light curves of the late-type detached eclipsing binary BH Vir (G0V + G5V, P =0 : 81687099). This binary system has been observed during four cam- paigns at the Calar Alto Observatory (Almeria, Spain) and at the European Southern Observatory (La Silla, Chile). This observations are part of a 6 yearuvby and H monitoring program of low mass eclipsing binaries which main objective is to provide accurate absolute astrophys- ical parameters for late-type main sequence stars. 1585 points spreaded over the binary period and covering both eclipses are given. The internal accuracy of the standard photometry measured as the mean RMS of the dierences between stand…

X-RAY AND OPTICAL OBSERVATIONS OF A 0535+26

2011

We present recent contemporaneous X-ray and optical observations of the Be/X-ray binary system A\,0535+26 with the \textit{Fermi}/Gamma-ray Burst Monitor (GBM) and several ground-based observatories. These new observations are put into the context of the rich historical data (since $\sim$1978) and discussed in terms of the neutron star Be-disk interaction. The Be circumstellar disk was exceptionally large just before the 2009 December giant outburst, which may explain the origin of the unusual recent X-ray activity of this source. We found a peculiar evolution of the pulse profile during this giant outburst, with the two main components evolving in opposite ways with energy. A hard 30-70 mH…

Pulsating B and Be Stars in the Magellanic Clouds

2010

Stellar pulsations in main-sequence B-type stars are driven by the κ-mechanism due to the Fe-group opacity bump. The current models do not predict the presence of instability strips in the B spectral domain at very low metallicities. As the metallicity of the Magellanic Clouds (MC) has been measured to be around Z = 0. 002 for the Small Magellanic Cloud (SMC) and Z = 0. 007 for the Large Magellanic Cloud (LMC), they constitute a very suitable objects to test these predictions. The aim of this work is to investigate the existence of B-type pulsators at low metallicities, searching for short-term periodic variability in a large sample of B and Be stars from the MC with accurately determined f…

Activity, colour anomalies and temperature determination in solar-type stars

2008

Legri Instrument Health. A Historical Review

2001

LEGRI has been operating successfully on MINISAT-01 since its switch-on the 22nd of May 1997. HouseKeeping (HK) data have been continuously received for nearly two years by LEGRI SOC in Valencia, and subsequently checked on a daily basis and then stored for long term monitoring analysis. LEGRI HouseKeeping data include three critical operating parameters: temperature, power and polarisation voltages. Six temperature sensors are spread over the different LEGRI units: Detector Unit, Data Processing Unit, High Voltage Unit and Star Sensor. Voltages are measured at eight different points. Detector Unit temperature and polarisation voltage are the critical parameters for LEGRI operation. Solid s…

Reddening map around ? Orionis

1990

uvbyβ photometry has been done for early-type stars in the surroundings of the shell star α Ori. The reddening maps show the presence of irregularly distributed absorbing material.

Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD 51452

2012

International audience; Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the κ-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way, p-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type and cooler. Aims. We observed a B0IVe star, HD 51452, with the high-precision, high-cadence photometric CoRoT satellite and high-resolution, ground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra a…

A photometric study of Be stars located in the seismology fields of COROT

2007

Context: In preparation for the COROT mission, an exhaustive photometric study of Be stars located in the seismology fields of the COROT mission has been performed. The very precise and long-time-spanned photometric observations gathered by the COROT satellite will give important clues of the origin of the Be phenomenon. Aims: The aim of this work is to find short-period variable Be stars located in the seismology fields of COROT and to study and characterise their pulsational properties. Methods: Light curves obtained at the Observatorio de Sierra Nevada together with data from Hipparcos and ASAS-3 of a total of 84 Be stars have been analysed in order to search for short-term variations. W…

Legri Operations. Detectors and Detector Stability

2001

Two years after launch (04.21.97), LEGRI is operating on Minisat-01 in a LEO orbit. The LEGRI detector plane is formed by two type of gamma-ray solid state detectors: HgI2 and CdZnTe. Detectors are embedded in a box containing the FEE and DFE electronics. This box provides an effective detector passive shielding. Detector plane is multiplexed by a Coded Aperture System located at 54 cm and a Ta Collimator with a FCFOV of 22° and 2° angular resolution. The aim of this paper is to summarize the detector behaviour in three different time scales: before launch, during the in-orbit check-out period (IOC), and after two years of routine operation in space. Main results can be summarized as follow…

Multiperiodic pulsations in the Be stars NW Serpentis and V1446 Aquilae

2007

Aims.We present accurate photometric time series of two Be stars: NW Ser and V1446 Aql . Both stars were observed at the Observatorio de Sierra Nevada (Granada) in July 2003 with an automatic four-channel Strömgren photometer. We also present a preliminary theoretical study showing that the periodic variations exhibited by these stars can be due to pulsation. Methods.An exhaustive Fourier analysis together with a least-square fitting has been carried out on the time series for all four Strömgren bands. Several independent frequencies and non-periodic trends explain most of the variance. A theoretical non-adiabatic code applied to stellar models for these stars shows that g-modes are unstabl…

Photometric variability of the Be star CoRoT-ID 102761769

2010

Classical Be stars are rapid rotators of spectral type late O to early A and luminosity class V-III, wich exhibit Balmer emission lines and often a near infrared excess originating in an equatorially concentrated circumstellar envelope, both produced by sporadic mass ejection episodes. The causes of the abnormal mass loss (the so-called Be phenomenon) are as yet unknown. For the first time, we can now study in detail Be stars outside the Earth's atmosphere with sufficient temporal resolution. We investigate the variability of the Be Star CoRoT-ID 102761769 observed with the CoRoT satellite in the exoplanet field during the initial run. One low-resolution spectrum of the star was obtained wi…

Low-amplitude variations detected by CoRoT in the B8IIIe star HD 175869

2009

International audience; Context: The origin of the short-term variability in Be stars remains a matter of controversy. Pulsations and rotational modulation are the components of the favored hypothesis. Aims: We present our analysis of CoRoT data of the B8IIIe star HD 175869 observed during the first short run in the center direction (SRC1). Methods: We review both the instrumental effects visible in the CoRoT light curve and the analysis methods used by the CoRoT Be team. We applied these methods to the CoRoT light curve of the star HD 175869. A search for line-profile variations in the spectroscopic data was also performed. We also searched for a magnetic field, by applying the LSD techniq…

Detection of a large Be circumstellar disk during X-ray quiescence of XTE J1946+274

2014

We present a multiwavelength study of the Be/X-ray binary system XTE J1946+274 with the main goal of better characterizing its behavior during X-ray quiescence. We aim to shed light on the mechanism which triggers the X-ray activity for this source. XTE J1946+274 was observed by Chandra-ACIS during quiescence in 2013 March 12. In addition, this source has been monitored from the ground-based astronomical observatories of El Teide (Tenerife, Spain), Roque de los Muchachos (La Palma, Spain) and Sierra Nevada (Granada, Spain) since 2011 September, and from the TUBITAK National Observatory (Antalya, Turkey) since 2005 April. We have performed spectral and photometric temporal analyses in order …

Pulsations in the late-type Be star HD 50 209 detected by CoRoT

2009

The presence of pulsations in late-type Be stars is still a matter of controversy. It constitutes an important issue to establish the relationship between non-radial pulsations and the mass-loss mechanism in Be stars. To contribute to this discussion, we analyse the photometric time series of the B8IVe star HD 50209 observed by the CoRoT mission in the seismology field. We use standard Fourier techniques and linear and non-linear least squares fitting methods to analyse the CoRoT light curve. In addition, we applied detailed modelling of high-resolution spectra to obtain the fundamental physical parameters of the star. We have found four frequencies which correspond to gravity modes with az…

Background in low Earth orbits measured by LEGRI telescope – short and long term variability

1999

Abstract In this paper we present the first Low Energy Gamma Ray Imager (LEGRI) background measurements which were carried out in the earlier nominal operation activities of LEGRI Instrument on board MINISAT-01, after initial spacecraft and instrument check-up procedures. Short term (daily) and expected long term background variability is presented. A background model is also discussed in order to be used for celestial γ-ray emitters observations.

Absolute parameters for binary systems

1997

New high-quality light curves of the late-type binary system BH Vir have been obtained during a 6 year photometric uvby and monitoring program of low mass eclipsing binaries (Clement et al. 1997), hereafter Papers I and II. This paper presents detailed analysis of this binary based on the four light curves obtained within our program. The activity wave superimposed on the eclipse-modulated light curves has been adjusted and removed by using a new iterative application of the standard EBOP code together with truncated Fourier Series fittings. Combining the recent radial velocity curves (Popper 1995) with the geometrical elements deduced from the "clean" photometric light curves, the absolute…

The second data release of the INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS DR2)

2014

The INT/WFC Photometric H-Alpha Survey of the Northern Galactic Plane (IPHAS) is a 1800 square degrees imaging survey covering Galactic latitudes |b| < 5 deg and longitudes l = 30 to 215 deg in the r, i and H-alpha filters using the Wide Field Camera (WFC) on the 2.5-metre Isaac Newton Telescope (INT) in La Palma. We present the first quality-controlled and globally-calibrated source catalogue derived from the survey, providing single-epoch photometry for 219 million unique sources across 92% of the footprint. The observations were carried out between 2003 and 2012 at a median seeing of 1.1 arcsec (sampled at 0.33 arcsec/pixel) and to a mean 5\sigma-depth of 21.2 (r), 20.0 (i) and 20.3 (H-a…

Absolute parameters for binary systems

1997

New light curves of the late-type binary sys- tem ZZ UMa were obtained during a uvby and H mon- itoring program on low mass eclipsing binaries, that has been carried out in a six year photometric observational program (Clement et al. 1997a, Paper I). The main goal of the program is to obtain accurate absolute parameters for stars in the low and intermediate mass range, in order to improve the Mass-Luminosity Relationship (MLR) at the end of the main sequence. This paper presents a complete analysis of the rst uvby light curves of the late-type detached eclipsing binary ZZ UMa. This binary system has been observed during eight campaigns at the Calar Alto Observatory (Almeria, Spain). The act…

The pulsations of the B5IVe star HD 181231 observed with CoRoT and ground-based spectroscopy

2009

International audience; Context: HD 181231 is a B5IVe star, which has been observed with the CoRoT satellite during ~5 consecutive months and simultaneously from the ground in spectroscopy and spectropolarimetry. Aims: By analysing these data, we aim to detect and characterize as many pulsation frequencies as possible, to search for the presence of beating effects possibly at the origin of the Be phenomenon. Our results will also provide a basis for seismic modelling. Methods: The fundamental parameters of the star are determined from spectral fitting and from the study of the circumstellar emission. The CoRoT photometric data and ground-based spectroscopy are analysed using several Fourier…

The B0.5IVe CoRoT target HD 49 330. II. Spectroscopic ground-based observations

2009

Context. We present spectroscopic ground-based observations of the early Be star HD 49330 obtained simultaneously with the CoRoT-LRA1 run just before the burst observed in the CoRoT data. Aims. Ground-based spectroscopic observations of the early Be star HD 49330 obtained during the precursor phase and just before the start of an outburst allow us to disantangle stellar and circumstellar contributions and identify modes of stellar pulsations in this rapidly rotating star. Methods. Time series analysis (TSA) is performed on photospheric line profiles of He i and Si iii by means of the least squares method. Results. We find two main frequencies f1 = 11.86 c d^−1 and f2 = 16.89 c d^−1 which ca…

The B0.5IVe CoRoT target HD 49 330. I. Photometric analysis from CoRoT data

2009

Context. Be stars undergo outbursts producing a circumstellar disk from the ejected material. The beating of non-radial pulsations has been put forward as a possible mechanism of ejection. Aims. We analyze the pulsational behavior of the early B0.5IVe star HD 49330 observed during the first CoRoT long run towards the Galactical anticenter (LRA1). This Be star is located close to the lower edge of the β Cephei instability strip in the HR diagram and showed a 0.03 mag outburst during the CoRoT observations. It is thus an ideal case for testing the aforementioned hypothesis. Methods. We analyze the CoRoT light curve of HD 49330 usin g Fourier methods and non-lin ear least square fitting. Resul…

Low-amplitude variations detected by CoRoT in the B8IIIe star HD 175 869

2009

Context.The origin of the short-term variability in Be stars remains a matter of controversy. Pulsations and rotational modulation are the components of the favored hypothesis.Aims.We present our analysis of CoRoT data of the B8IIIe star HD 175869 observed during the first short run in the center direction (SRC1).Methods.We review both the instrumental effects visible in the CoRoT light curve and the analysis methods used by the CoRoT Be team. We applied these methods to the CoRoT light curve of the star HD 175869. A search for line-profile variations in the spectroscopic data was also performed. We also searched for a magnetic field, by applying the LSD technique to spectropolarimetric dat…

The pulsations of the B5IVe star HD 181 231 observed with CoRoT and ground-based spectroscopy

2009

Context. HD 181231 is a B5IVe star, which has been observed with the CoRoT satellite during ∼5 consecutive months and simultaneously from the ground in spectroscopy and spectropolarimetry. Aims. By analysing these data, we aim to detect and characterize as many pulsation frequencies as possible, to search for the presence of beating effects possibly at the origin of the Be phenomenon. Our results will also pr ovide a basis for seismic modelling. Methods. The fundamental parameters of the star are determined from spectral fitting and from the study of the circumstellar emission. The CoRoT photometric data and ground-based spectroscopy are analysed using several Fourier Techniques: CLEAN-NG,P…

Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD 51452

2012

Context.Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the κ-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way,p-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type and cooler.Aims.We observed a B0IVe star, HD 51452,with the high-precision, high-cadence photometric CoRoT satellite and high-resolution, ground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra available in the BeSS atabase.…

Pulsations of HD 181231

2009

HD181231 is a B5IVe star, which has been observed with the CoRoT satellite during ~5 consecutive months and simultaneously from the ground in spectroscopy and spectropolarimetry. By analysing these data, we aim to detect and characterize as many pulsation frequencies as possible, to search for the presence of beating effects possibly at the origin of the Be phenomenon. Our results will also provide a basis for seismic modelling. The fundamental parameters of the star are determined from spectral fitting and from the study of the circumstellar emission. The CoRoT photometric data and ground-based spectroscopy are analysed using several Fourier techniques: Clean-ng, Pasper, and Tisaft, as wel…

Fourier analysis of HD 49330 CoRoT light curve

2009

Be stars undergo outbursts producing a circumstellar disk from the ejected material. The beating of non-radial pulsations has been put forward as a possible mechanism of ejection. We analyze the pulsational behavior of the early B0.5IVe star HD 49330 observed during the first CoRoT long run towards the Galactical anticenter (LRA1). This Be star is located close to the lower edge of the {beta} Cephei instability strip in the HR diagram and showed a 0.03mag outburst during the CoRoT observations. It is thus an ideal case for testing the aforementioned hypothesis.