J. Borissova - Academia.edu (original) (raw)

Papers by J. Borissova

Research paper thumbnail of Discovery of a mid-infrared protostellar outburst of exceptional amplitude

Monthly Notices of the Royal Astronomical Society

We report the discovery of a mid-infrared outburst in a young stellar object (YSO) with an amplit... more We report the discovery of a mid-infrared outburst in a young stellar object (YSO) with an amplitude close to 8 mag at λ ≈ 4.6 μm. WISEA J142238.82−611553.7 is one of 23 highly variable Wide-field Infrared Survey Explorer (WISE) sources discovered in a search of infrared dark clouds (IRDCs). It lies within the small IRDC G313.671−0.309 (d ≈2.6 kpc), seen by the Herschel/Hi-Gal survey as a compact massive cloud core that may have been measurably warmed by the event. Pre-outburst data from Spitzer in 2004 suggest it is a class I YSO, a view supported by observation of weak 2.12 μm H2 emission in an otherwise featureless red continuum spectrum in 2019 (6 mag below the peak in Ks). Spitzer, WISE, and VISTA Variables in the Via Lactea (VVV) data show that the outburst began by 2006 and has a duration >13 yr, with a fairly flat peak from 2010 to 2014. The low pre-outburst luminosity implies a low-mass progenitor. The outburst luminosity of a few × 102 L⊙ is consistent with an accretion...

Research paper thumbnail of Small-scale star formation as revealed by VVVX galactic cluster candidates

Monthly Notices of the Royal Astronomical Society

We report a search and analysis of obscured cluster candidates in the ‘VISTA Variables in the Via... more We report a search and analysis of obscured cluster candidates in the ‘VISTA Variables in the Via Lactea eXtended (VVVX)’ ESO Public Survey area encompassing the region between 229${_{.}^{\circ}}$4 < l < 295${_{.}^{\circ}}$2 and −4${_{.}^{\circ}}$3 < b < 4${_{.}^{\circ}}$4 of the southern Galactic disc. We discover and propose 88 new clusters. We improve the completeness of the embedded cluster population in this region, adding small size (linear diameters of 0.2–1.4 pc) and relatively far objects (heliocentric distance between 2 and 4 kpc) to existing catalogues. Nine candidates are proposed to be older open cluster candidates. Three of them (VVVX CL 204, CL 207, CL 208) have sufficient numbers of well-resolved stellar members to allow us to determine some basic cluster parameters. We confirm their nature as older, low-mass open clusters. Photometric analysis of 15 known clusters shows that they have ages above 20 Myr, and masses below 2000 M⊙: in general, their prope...

Research paper thumbnail of Multi-wavelength study in the region of IRAS 16571-4029 and 16575-4023 sources

Research paper thumbnail of IC 1613 OB Associations and Star Cluster Candidates

Symposium - International Astronomical Union

Moderately deep ground based UBV images are used to investigate the OB associations and star clus... more Moderately deep ground based UBV images are used to investigate the OB associations and star clusters in IC 1613. Fifty eight OB associations with sizes between 30 and 130 pc are outlined. The iteration between associations and superbubbles in IC 1613 was analyzed. The lack of star clusters was confirmed.

Research paper thumbnail of Near Infrared Photometry of New Galactic Globular Clusters GC 01 and GC 02

Symposium - International Astronomical Union

We present a preliminary report on the first deep near infrared photometry of 2MASS GC 01 and 2MA... more We present a preliminary report on the first deep near infrared photometry of 2MASS GC 01 and 2MASS GC 02 - new Galactic globular cluster candidates, discovered by the 2MASS. The red giant branch slopes yielded [Fe/H]=-0.42 ± 0.15 dex and [Fe/H]=-0.66 ± 0.17 dex, respectively for GC 01 and GC 02. We estimated the reddening towards GC 01 and GC 02: E(B - V) = 5.36 ± 0.20, and E(B - V) = 4.55 ± 0.17. The calculated distance moduli to the clusters are: (m - M)0 = 13.53 ± 0.27 and (m - M)0 = 14.53 ± 0.31 for GC 01 and GC 02. Our best fit for the radial surface brightness profile of GC 02 yields: lg(rc) = 1.40, lg(rh) = 1.54, lg(rt) = 1.31, and c=1.60. CC 01 is less concentrated: lg(rc) = 1.63, lg(rh) = 1.7, lg(rt) = 1.25, and c=1.41.

Research paper thumbnail of The Emergence of the Infrared Transient VVV-WIT-06

The Astrophysical Journal

Please check the manuscript for details of any other licences that may have been applied and it i... more Please check the manuscript for details of any other licences that may have been applied and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (http://uhra.herts.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge. Take down policy If you believe that this document breaches copyright please contact us providing details, any such items will be temporarily removed from the repository pending investigation.

Research paper thumbnail of Young Stellar Clusters Containing Massive Young Stellar Objects in the VVV Survey

The Astronomical Journal, 2016

The purpose of this research is to study the connections of the global properties of eight young ... more The purpose of this research is to study the connections of the global properties of eight young stellar clusters projected in the Vista Variables in the Via Lactea (VVV) ESO Large Public Survey disk area and their young stellar object (YSO) populations. The analysis is based on the combination of spectroscopic parallax-based reddening and distance determinations with main-sequence and pre-main-sequence ishochrone fitting to determine the basic parameters (reddening, age, distance) of the sample clusters. The lower mass limit estimations show that all clusters are low or intermediate mass (between 110 and 1800M e), the slope Γ of the obtained present-day mass functions of the clusters is close to the Kroupa initial mass function. The YSOs in the cluster's surrounding fields are classified using low resolution spectra, spectral energy distribution fits with theoretical predictions, and variability, taking advantage of multi-epoch VVV observations. All spectroscopically confirmed YSOs (except one) are found to be massive (more than 8 M e). Using VVV and GLIMPSE color-color cuts we have selected a large number of new YSO candidates, which are checked for variability and 57% are found to show at least lowamplitude variations. In few cases it was possible to distinguish between YSO and AGB classifications on the basis of light curves.

Research paper thumbnail of Kinematics of the Ionized Gas in the Irregular Galaxies IC 10 and NGC 4449

Symposium - International Astronomical Union, 1999

We have searched for supernova remnants (SNRs) in the irregular galaxies IC 10 and NGC 4449 by me... more We have searched for supernova remnants (SNRs) in the irregular galaxies IC 10 and NGC 4449 by means of Fabry-Perot interferometry in Hα and [SII] lines, complemented by radio continuum observations. We find several new SNR candidates in each galaxy in addition to the known ones. Although these galaxies have several common properties, the distributions of SNRs in each galaxy is different. This shows that the star formation mechanisms in these galaxies act in different ways, in favor of the formation of a large nebular HII complex in IC 10, similar to 30 Dor in the Large Magellanic Cloud. We are studying the conditions over which these different star formation histories take place.

Research paper thumbnail of Properties of massive stars in four clusters of the VVV survey

New Astronomy, 2015

The evolution of massive stars is only partly understood. Observational constraints can be obtain... more The evolution of massive stars is only partly understood. Observational constraints can be obtained from the study of massive stars located in young massive clusters. The ESO Public Survey "VISTA Variables in the Vía Lácteá (VVV)" discovered several new clusters hosting massive stars. We present an analysis of massive stars in four of these new clusters. Our aim is to provide constraints on stellar evolution and to better understand the relation between different types of massive stars. We use the radiative transfer code CMFGEN to analyse K-band spectra of twelve stars with spectral types ranging from O and B to WN and WC. We derive the stellar parameters of all targets as well as surface abundances for a subset of them. In the Hertzsprung-Russell diagram, the Wolf-Rayet stars are more luminous or hotter than the O stars. From the log(C/N)-log(C/He) diagram, we show ✩ Based on observations with ISAAC/VLT/ESO (programme 087.D-0341A), New Technology Telescope at ESO/La Silla Observatory (programme 087.D-0490A), VVV ESO Large Survey (programme 179.B-2002) and with SOAR (programme CN2012A-616).

Research paper thumbnail of Spectroscopic Abundances and Radial Velocities of the Galactic Globular Clusters 2MASS GC01 and 2MASS GC02: Preliminary Results

Eso Astrophysics Symposia, 2009

ABSTRACT We have presented the preliminary results of the first spectroscopic observations of the... more ABSTRACT We have presented the preliminary results of the first spectroscopic observations of the galactic globular clusters 2MASS GC01 and 2MASS GC02. The metallicity, radial velocities and distances to the clusters are determined.

Research paper thumbnail of Search for undetected star clusters in our Galaxy in the 2MASS database

A simple and robust method, based on stellar surface density was proposed in order to search for ... more A simple and robust method, based on stellar surface density was proposed in order to search for undetected star clusters in our Galaxy on the base of the 2MASS catalogue. The zone of the sky of galactic latitude between -80 and -40 degree was choosen to test the method. As a result we identify approx. 30% of suspected cluster candidtes.

Research paper thumbnail of Radial Distribution of Red Giant Branch Stars of Galactic Globular Clusters in 2MASS Database

Research paper thumbnail of JHKs photometry of GLIMPSE-C02 (Kurtev+, 2008)

Research paper thumbnail of Revealing the Galactic “Underground” Star Formation

Research paper thumbnail of Massive open star clusters using the VVV survey IV. WR 62-2, a new very massive star in the core of the VVV CL041 cluster

Astronomy & Astrophysics, 2015

Context. The ESO public survey VISTA Variables in the Vía Láctea (VVV) has contributed with deep ... more Context. The ESO public survey VISTA Variables in the Vía Láctea (VVV) has contributed with deep multi-epoch photometry of the Galactic bulge and the adjacent part of the disk over 526 sq. deg. More than a hundred cluster candidates have been reported thanks to this survey. Aims. We present the fifth article in a series of papers focused on young and massive clusters discovered in the VVV survey. In this paper, we present the physical characterization of five clusters with a spectroscopically confirmed OB-type stellar population. Methods. To characterize the clusters, we used near-infrared photometry (J, H, and K S) from the VVV survey and near-infrared K-band spectroscopy from ISAAC at VLT, following the methodology presented in the previous articles of the series. Results. All clusters in our sample are very young (ages between 1-20 Myr), and their total mass are between (1.07 +0.40 −0.30) × 10 2 M and (4.17 +4.15 −2.08) × 10 3 M. We observed a relation between the clusters total mass M ecl and the mass of their most massive stellar member m max , for clusters with an age <10 Myr.

Research paper thumbnail of Chemical abundances in giant stars of newly discovered infrared globular clusters 2MASS GC02 and Mercer 5

We present a study of abundances of two hidden Galactic globular clus- ters: Mercer 5 and 2MASS G... more We present a study of abundances of two hidden Galactic globular clus- ters: Mercer 5 and 2MASS GC02, using high-resolution (IR) spectra. We measure accurate radial velocities of vr = +194 ± 0.3 km s-1 for Mer- cer 5 star 1 and vr = +177 ± 0.3 km s-1 for Mercer 5 star 2. We find [Fe/H] = -1.00 ± 0.02 dex and average a - elements enhancement of +0.40 ± 0.02 dex for Mercer 5, while for 2MASS GC02 we only make a qualitative analysis, due to insufficient signal to noise of the target spectra.

Research paper thumbnail of VVV High Proper Motion Survey

Here we present survey of proper motion stars towards the Galactic Bulge and an adjacent plane re... more Here we present survey of proper motion stars towards the Galactic Bulge and an adjacent plane region base on VISTA-VVV data. The searching method based on cross-matching photometric Ks-band CASU catalogs. The most interesting discoveries are shown.

Research paper thumbnail of Peering through the dust: Precise astrometry in the Galactic mid-plane with the VVV survey

EAS Publications Series, 2014

Research paper thumbnail of LMC RR Lyrae radial velocities (Borissova+, 2004)

The spectroscopic observations were taken with the FORS1 multi-slit spectrograph at the ESO Very ... more The spectroscopic observations were taken with the FORS1 multi-slit spectrograph at the ESO Very Large Telescopte (VLT) Unit Telescope 1 (UT1), during the nights of 10 and 11 January 2003. (2 data files).

Research paper thumbnail of Radial velocities of LMC RR Lyrae (Borissova+, 2006)

In Paper I (Cat. J/A+A/423/97) we presented radial velocities, metallicities and K-band magnitude... more In Paper I (Cat. J/A+A/423/97) we presented radial velocities, metallicities and K-band magnitudes of 74 RR Lyrae stars in the inner regions of the LMC. The optical low resolution spectra were obtained with the FORS1 at the ESO VLT and near-IR photometry images with the SOFI infrared array at the ESO NTT. We have chosen to extend this sample by using the MACHO (Alcock et al., 2000, Cat. J/ApJ/542/257) and OGLE (Zebrun et al., 2001AcA....51..317Z) databases to seven fields of the LMC bar, at distances from 0.4 to 2.5 degrees away from the rotation center (Soszynski et al., 2003, Cat. J/AcA/53/93). Two of these new fields are centered on the LMC clusters NGC 1835 and NGC 2019. We also observed additional stars in the fields LMC-4, LMC-9 and LMC-14 defined in Paper I. (1 data file).

Research paper thumbnail of Discovery of a mid-infrared protostellar outburst of exceptional amplitude

Monthly Notices of the Royal Astronomical Society

We report the discovery of a mid-infrared outburst in a young stellar object (YSO) with an amplit... more We report the discovery of a mid-infrared outburst in a young stellar object (YSO) with an amplitude close to 8 mag at λ ≈ 4.6 μm. WISEA J142238.82−611553.7 is one of 23 highly variable Wide-field Infrared Survey Explorer (WISE) sources discovered in a search of infrared dark clouds (IRDCs). It lies within the small IRDC G313.671−0.309 (d ≈2.6 kpc), seen by the Herschel/Hi-Gal survey as a compact massive cloud core that may have been measurably warmed by the event. Pre-outburst data from Spitzer in 2004 suggest it is a class I YSO, a view supported by observation of weak 2.12 μm H2 emission in an otherwise featureless red continuum spectrum in 2019 (6 mag below the peak in Ks). Spitzer, WISE, and VISTA Variables in the Via Lactea (VVV) data show that the outburst began by 2006 and has a duration >13 yr, with a fairly flat peak from 2010 to 2014. The low pre-outburst luminosity implies a low-mass progenitor. The outburst luminosity of a few × 102 L⊙ is consistent with an accretion...

Research paper thumbnail of Small-scale star formation as revealed by VVVX galactic cluster candidates

Monthly Notices of the Royal Astronomical Society

We report a search and analysis of obscured cluster candidates in the ‘VISTA Variables in the Via... more We report a search and analysis of obscured cluster candidates in the ‘VISTA Variables in the Via Lactea eXtended (VVVX)’ ESO Public Survey area encompassing the region between 229${_{.}^{\circ}}$4 < l < 295${_{.}^{\circ}}$2 and −4${_{.}^{\circ}}$3 < b < 4${_{.}^{\circ}}$4 of the southern Galactic disc. We discover and propose 88 new clusters. We improve the completeness of the embedded cluster population in this region, adding small size (linear diameters of 0.2–1.4 pc) and relatively far objects (heliocentric distance between 2 and 4 kpc) to existing catalogues. Nine candidates are proposed to be older open cluster candidates. Three of them (VVVX CL 204, CL 207, CL 208) have sufficient numbers of well-resolved stellar members to allow us to determine some basic cluster parameters. We confirm their nature as older, low-mass open clusters. Photometric analysis of 15 known clusters shows that they have ages above 20 Myr, and masses below 2000 M⊙: in general, their prope...

Research paper thumbnail of Multi-wavelength study in the region of IRAS 16571-4029 and 16575-4023 sources

Research paper thumbnail of IC 1613 OB Associations and Star Cluster Candidates

Symposium - International Astronomical Union

Moderately deep ground based UBV images are used to investigate the OB associations and star clus... more Moderately deep ground based UBV images are used to investigate the OB associations and star clusters in IC 1613. Fifty eight OB associations with sizes between 30 and 130 pc are outlined. The iteration between associations and superbubbles in IC 1613 was analyzed. The lack of star clusters was confirmed.

Research paper thumbnail of Near Infrared Photometry of New Galactic Globular Clusters GC 01 and GC 02

Symposium - International Astronomical Union

We present a preliminary report on the first deep near infrared photometry of 2MASS GC 01 and 2MA... more We present a preliminary report on the first deep near infrared photometry of 2MASS GC 01 and 2MASS GC 02 - new Galactic globular cluster candidates, discovered by the 2MASS. The red giant branch slopes yielded [Fe/H]=-0.42 ± 0.15 dex and [Fe/H]=-0.66 ± 0.17 dex, respectively for GC 01 and GC 02. We estimated the reddening towards GC 01 and GC 02: E(B - V) = 5.36 ± 0.20, and E(B - V) = 4.55 ± 0.17. The calculated distance moduli to the clusters are: (m - M)0 = 13.53 ± 0.27 and (m - M)0 = 14.53 ± 0.31 for GC 01 and GC 02. Our best fit for the radial surface brightness profile of GC 02 yields: lg(rc) = 1.40, lg(rh) = 1.54, lg(rt) = 1.31, and c=1.60. CC 01 is less concentrated: lg(rc) = 1.63, lg(rh) = 1.7, lg(rt) = 1.25, and c=1.41.

Research paper thumbnail of The Emergence of the Infrared Transient VVV-WIT-06

The Astrophysical Journal

Please check the manuscript for details of any other licences that may have been applied and it i... more Please check the manuscript for details of any other licences that may have been applied and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (http://uhra.herts.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge. Take down policy If you believe that this document breaches copyright please contact us providing details, any such items will be temporarily removed from the repository pending investigation.

Research paper thumbnail of Young Stellar Clusters Containing Massive Young Stellar Objects in the VVV Survey

The Astronomical Journal, 2016

The purpose of this research is to study the connections of the global properties of eight young ... more The purpose of this research is to study the connections of the global properties of eight young stellar clusters projected in the Vista Variables in the Via Lactea (VVV) ESO Large Public Survey disk area and their young stellar object (YSO) populations. The analysis is based on the combination of spectroscopic parallax-based reddening and distance determinations with main-sequence and pre-main-sequence ishochrone fitting to determine the basic parameters (reddening, age, distance) of the sample clusters. The lower mass limit estimations show that all clusters are low or intermediate mass (between 110 and 1800M e), the slope Γ of the obtained present-day mass functions of the clusters is close to the Kroupa initial mass function. The YSOs in the cluster's surrounding fields are classified using low resolution spectra, spectral energy distribution fits with theoretical predictions, and variability, taking advantage of multi-epoch VVV observations. All spectroscopically confirmed YSOs (except one) are found to be massive (more than 8 M e). Using VVV and GLIMPSE color-color cuts we have selected a large number of new YSO candidates, which are checked for variability and 57% are found to show at least lowamplitude variations. In few cases it was possible to distinguish between YSO and AGB classifications on the basis of light curves.

Research paper thumbnail of Kinematics of the Ionized Gas in the Irregular Galaxies IC 10 and NGC 4449

Symposium - International Astronomical Union, 1999

We have searched for supernova remnants (SNRs) in the irregular galaxies IC 10 and NGC 4449 by me... more We have searched for supernova remnants (SNRs) in the irregular galaxies IC 10 and NGC 4449 by means of Fabry-Perot interferometry in Hα and [SII] lines, complemented by radio continuum observations. We find several new SNR candidates in each galaxy in addition to the known ones. Although these galaxies have several common properties, the distributions of SNRs in each galaxy is different. This shows that the star formation mechanisms in these galaxies act in different ways, in favor of the formation of a large nebular HII complex in IC 10, similar to 30 Dor in the Large Magellanic Cloud. We are studying the conditions over which these different star formation histories take place.

Research paper thumbnail of Properties of massive stars in four clusters of the VVV survey

New Astronomy, 2015

The evolution of massive stars is only partly understood. Observational constraints can be obtain... more The evolution of massive stars is only partly understood. Observational constraints can be obtained from the study of massive stars located in young massive clusters. The ESO Public Survey "VISTA Variables in the Vía Lácteá (VVV)" discovered several new clusters hosting massive stars. We present an analysis of massive stars in four of these new clusters. Our aim is to provide constraints on stellar evolution and to better understand the relation between different types of massive stars. We use the radiative transfer code CMFGEN to analyse K-band spectra of twelve stars with spectral types ranging from O and B to WN and WC. We derive the stellar parameters of all targets as well as surface abundances for a subset of them. In the Hertzsprung-Russell diagram, the Wolf-Rayet stars are more luminous or hotter than the O stars. From the log(C/N)-log(C/He) diagram, we show ✩ Based on observations with ISAAC/VLT/ESO (programme 087.D-0341A), New Technology Telescope at ESO/La Silla Observatory (programme 087.D-0490A), VVV ESO Large Survey (programme 179.B-2002) and with SOAR (programme CN2012A-616).

Research paper thumbnail of Spectroscopic Abundances and Radial Velocities of the Galactic Globular Clusters 2MASS GC01 and 2MASS GC02: Preliminary Results

Eso Astrophysics Symposia, 2009

ABSTRACT We have presented the preliminary results of the first spectroscopic observations of the... more ABSTRACT We have presented the preliminary results of the first spectroscopic observations of the galactic globular clusters 2MASS GC01 and 2MASS GC02. The metallicity, radial velocities and distances to the clusters are determined.

Research paper thumbnail of Search for undetected star clusters in our Galaxy in the 2MASS database

A simple and robust method, based on stellar surface density was proposed in order to search for ... more A simple and robust method, based on stellar surface density was proposed in order to search for undetected star clusters in our Galaxy on the base of the 2MASS catalogue. The zone of the sky of galactic latitude between -80 and -40 degree was choosen to test the method. As a result we identify approx. 30% of suspected cluster candidtes.

Research paper thumbnail of Radial Distribution of Red Giant Branch Stars of Galactic Globular Clusters in 2MASS Database

Research paper thumbnail of JHKs photometry of GLIMPSE-C02 (Kurtev+, 2008)

Research paper thumbnail of Revealing the Galactic “Underground” Star Formation

Research paper thumbnail of Massive open star clusters using the VVV survey IV. WR 62-2, a new very massive star in the core of the VVV CL041 cluster

Astronomy & Astrophysics, 2015

Context. The ESO public survey VISTA Variables in the Vía Láctea (VVV) has contributed with deep ... more Context. The ESO public survey VISTA Variables in the Vía Láctea (VVV) has contributed with deep multi-epoch photometry of the Galactic bulge and the adjacent part of the disk over 526 sq. deg. More than a hundred cluster candidates have been reported thanks to this survey. Aims. We present the fifth article in a series of papers focused on young and massive clusters discovered in the VVV survey. In this paper, we present the physical characterization of five clusters with a spectroscopically confirmed OB-type stellar population. Methods. To characterize the clusters, we used near-infrared photometry (J, H, and K S) from the VVV survey and near-infrared K-band spectroscopy from ISAAC at VLT, following the methodology presented in the previous articles of the series. Results. All clusters in our sample are very young (ages between 1-20 Myr), and their total mass are between (1.07 +0.40 −0.30) × 10 2 M and (4.17 +4.15 −2.08) × 10 3 M. We observed a relation between the clusters total mass M ecl and the mass of their most massive stellar member m max , for clusters with an age <10 Myr.

Research paper thumbnail of Chemical abundances in giant stars of newly discovered infrared globular clusters 2MASS GC02 and Mercer 5

We present a study of abundances of two hidden Galactic globular clus- ters: Mercer 5 and 2MASS G... more We present a study of abundances of two hidden Galactic globular clus- ters: Mercer 5 and 2MASS GC02, using high-resolution (IR) spectra. We measure accurate radial velocities of vr = +194 ± 0.3 km s-1 for Mer- cer 5 star 1 and vr = +177 ± 0.3 km s-1 for Mercer 5 star 2. We find [Fe/H] = -1.00 ± 0.02 dex and average a - elements enhancement of +0.40 ± 0.02 dex for Mercer 5, while for 2MASS GC02 we only make a qualitative analysis, due to insufficient signal to noise of the target spectra.

Research paper thumbnail of VVV High Proper Motion Survey

Here we present survey of proper motion stars towards the Galactic Bulge and an adjacent plane re... more Here we present survey of proper motion stars towards the Galactic Bulge and an adjacent plane region base on VISTA-VVV data. The searching method based on cross-matching photometric Ks-band CASU catalogs. The most interesting discoveries are shown.

Research paper thumbnail of Peering through the dust: Precise astrometry in the Galactic mid-plane with the VVV survey

EAS Publications Series, 2014

Research paper thumbnail of LMC RR Lyrae radial velocities (Borissova+, 2004)

The spectroscopic observations were taken with the FORS1 multi-slit spectrograph at the ESO Very ... more The spectroscopic observations were taken with the FORS1 multi-slit spectrograph at the ESO Very Large Telescopte (VLT) Unit Telescope 1 (UT1), during the nights of 10 and 11 January 2003. (2 data files).

Research paper thumbnail of Radial velocities of LMC RR Lyrae (Borissova+, 2006)

In Paper I (Cat. J/A+A/423/97) we presented radial velocities, metallicities and K-band magnitude... more In Paper I (Cat. J/A+A/423/97) we presented radial velocities, metallicities and K-band magnitudes of 74 RR Lyrae stars in the inner regions of the LMC. The optical low resolution spectra were obtained with the FORS1 at the ESO VLT and near-IR photometry images with the SOFI infrared array at the ESO NTT. We have chosen to extend this sample by using the MACHO (Alcock et al., 2000, Cat. J/ApJ/542/257) and OGLE (Zebrun et al., 2001AcA....51..317Z) databases to seven fields of the LMC bar, at distances from 0.4 to 2.5 degrees away from the rotation center (Soszynski et al., 2003, Cat. J/AcA/53/93). Two of these new fields are centered on the LMC clusters NGC 1835 and NGC 2019. We also observed additional stars in the fields LMC-4, LMC-9 and LMC-14 defined in Paper I. (1 data file).