1,721,069 research outputs found
The old open clusters Saurer A, B and C revisited
Full text linkWe report deep (V ≈ 24.0) VI CCD photometry of three fields centred in the regions of the old open clusters Saurer A, B and C. In the case of Saurer A, which is considered one of the oldest known open clusters, we also provide a comparison field. From the analysis of the photometry we claim that Saurer A is as old as M67 (≈5 Gyr), but more metal-poor (Z = 0.008). Moreover, it turns out to be the open cluster with the largest galactocentric distance so far detected. As for Saurer B, it closely resembles NGC 2158, and indeed is of intermediate age (1.8-2.2 Gyr) and significantly reddened. In this case we revise both the age and the distance with respect to previous studies, but we are not able to establish clearly the cluster metal abundance. Finally, Saurer C has an age of about 2 Gyr, but we emphasize that the precise determination of its properties is hampered by the heavy field star contamination. All of the photometry is available at the WEBDA data base: http://obswww.unige.ch/webda/navigation.html.Fil: Carraro, Giovanni. Università di Padova; ItaliaFil: Baume, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; Argentin
NGC 1883: a neglected intermediate-age open cluster located in the outskirts of the Galactic disc
Full text linkWe report on BVI CCD photometry of a field centred in the region of the open cluster NGC 1883, down to V= 21. This cluster has never been studied so far; we provide, for the first time, estimates of its fundamental parameters - namely radial extent, age, distance and reddening. We find that the cluster has a radius of about 2.5 arcmin, and shows signatures of dynamical relaxation. NGC 1883 is located in the anticentre direction, and exhibits a reddening in the range E(B-V) = 0.23-0.35, depending on the metal abundance. It turns out to be of intermediate age (1 Gyr old), and is quite distant for an open cluster. In fact, it is located 4.8 kpc from the Sun, and more than 13 kpc from the Galactic centre. This results makes NGC 1883 one of the most peripheral old open clusters, with important consequences for the trend of the metallicity with distance in the outer Galactic disc.Fil: Carraro, Giovanni. Università di Padova; ItaliaFil: Baume, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; Argentina. Università di Padova; ItaliaFil: Villanova, S.. Università di Padova; Itali
A study of the Galactic plane towardsl= 305°
Full text linkWe present optical (UBVIC) observations of a rich and complex field in the Galactic plane towards l ~ 305° and b ~ 0°. Our analysis reveals a significantly high interstellar absorption (AV ~ 10) and an abnormal extinction law in this line of sight. Availing a considerable number of colour combinations, the photometric diagrams allow us to derive new estimates of the fundamental parameters of the two open clusters Danks 1 and Danks 2. Due to the derived abnormal reddening law in this line of sight, both clusters appear much closer (to the Sun) than previously thought. Additionally, we present the optical colours and magnitudes of the WR 48a star, and its main parameters were estimated. The properties of the two embedded clusters, DBS2003 130 and 131, are also addressed. We identify a number of young stellar objects which are probable members of these clusters. This new material is then used to revisit the spiral structure in this sector of the Galaxy showing evidence of populations associated with the inner Galaxy Scutum-Crux arm.Fil: Baume, Gustavo Luis. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Carraro, Giovanni. European Southern Obvervatory; ChileFil: Momany, Y.. European Southern Obvervatory; Chil
A study of the two northern open clusters NGC 1582 and NGC 1663
Full text linkWe present CCD UBV(I)C observations obtained in the field of the previously unstudied northern open clusters NGC 1582 and NGC 1663. For the former, we also provide high-resolution spectra of the brightest stars and complement our data with Two-Micron All-Sky-Survey (2MASS) near-infrared photometry and with astrometric data from the Tycho-2 catalog. From the analysis of all these data, we argue that NGC 1582 is a very poor, quite large and heavily contaminated open cluster. It turns out to have a reddening EB-V = 0.35 +/- 0.03, to be situated 1100 +/- 100 pc from the Sun and to have an age of 300 +/- 100 Myr. On the other hand, we were not able to unambiguously clarify the nature of NGC 1663. By assuming it is a real cluster and from the analysis of its photometric diagrams, we found a color excess value EB-V = 0.20, an intermediate age value ( ~ 2000 Myr) and a distance of about 700 pc. The distribution of the stars in the region however suggests we are probably facing an open cluster remnant. As an additional result, we obtained aperture photometry of three previously unclassified galaxies placed in the field of NGC 1663 and performed a preliminary morphological classification of them.Fil: Baume, Gustavo Luis. Università di Padova; ItaliaFil: Villanova, S.. Università di Padova; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; ArgentinaFil: Carraro, Giovanni. Università di Padova; Itali
CCD UBVI photometry and polarimetry in the open cluster Trumpler 21
No full textCCD UBVI photometry was carried out in the field of the open cluster Trumpler 21. Our data locate the cluster at a distance of 1380 pc in a low absorption zone with E(B-V) = 0.25. The age of the cluster is estimated to be 25-30 × 106 yr based on the superposition of isochrones computed with mass loss and overshooting. The cluster mass spectrum has a slope of 1.44 similar to the typical value 1.35 for field stars. UBVRI polarimetry of its brightest members led us to the finding that diffuse interstellar material is responsible for both polarization percentage and its direction.Fil: Giorgi, Edgard Ervar Salvador. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Baume, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vazquez, Ruben Angel. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Feinstein, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Studying young stellar populations in G345.5+1.5 molecular cloud
No full textUsing different sky surveys, we studied IRAS sources and embedded clusters located in the G345.5+1.5 region. Our analysis comprises multi-wavelength (optical to radio) data, exploited using various methods: photometry, near-infrared spectroscopy for ten stars in the embedded cluster DBS-114, and astrometry. We estimated the main parameters of the embedded stellar populations in the G345.5+1.5 molecular cloud, such as their extent, reddening, age, and mass. We also found a consistent distance value using different approaches. For each studied population, we classified several point objects as early main sequence stars, stars with infrared excess, and class I/II YSOs. For the particular case of DBS 114, our spectral classification revealed four B-type stars, and we used astrometric information from GAIA EDR3. The combination of optical and infrared information revealed an abnormal reddening law in some embedded clusters. Our analysis favored a scenario with a Lyman continuum emission excess at some of the studied stellar populations.Fil: Baume, Gustavo Luis. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Ramirez Alegria, S.. Universidad de Antofagasta (uantof);Fil: Borissova, J.. Universidad de Valparaíso; Chil
The young open cluster Markarian 50
Full text linkWe report on a deep CCD UBV(RI)C photometric survey in the region of the young open cluster Markarian 50. The new photometric data allow us to extend the cluster membership down to V ≈ 17.5, about 2 mag deeper than any previous investigation. On the basis of these data we derive a distance d = 3460 ± 350 pc (Vo - Mv = 12.7 ± 0.2), which turns out to be only slightly lower than previous estimates. The cluster presents differential reddening, with E(B-V) values ranging from 0.69 to 1.1. The brightest member (HD 219460) is a double star, which we separate photometrically for the first time, providing individual magnitudes and colours for each component. One of them is a Wolf-Rayet (WR) star and, according to evolutionary models, the mass of its progenitor should be greater than ∼20 M⊙. The age obtained for the cluster is 7.5 ± 2 Myr and the mass function for the most massive stars (M > 1 M⊙) presents a slope x ≈ 1.0.Fil: Baume, Gustavo Luis. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Vazquez, Ruben Angel. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Carraro, Giovanni. Dipartamento Di Astronomia, Universita Di Padova; Itali
Photometric study of the young open cluster NGC 3293
Full text linkDeep and extensive CCD photometric observations at were
carried out in the area of the open cluster NGC 3293. The new data set allows
to see the entire cluster sequence down to , revealing that
stars with are evolving off the main sequence; stars with are
placed above it. According to our analysis, the cluster distance is ±
( ±
0.2) and its nuclear age is
8 ±
1 Myr. NGC 3293 contains an important fraction of pre–main sequence
(PMS) stars distributed along a parallel band to the ZAMS with masses from 1
to and a mean contraction age of 10 Myr. This last value
does not differ too much from the nuclear age estimate. If we take
into account the many factors that may affect the PMS star positions on the
colour–magnitude diagram, both ages can be perfectly reconciled. The star
formation rate, on the other hand, suggests that NGC 3293 stars formed surely
in one single event, therefore favouring a coeval process of star formation.
Using the data, we detected nineteen stars with signs of
emission in the region of NGC 3293, another
indication that the star formation process is still active in the region. The
computed initial mass function for the cluster has a slope of , a bit flatter than the typical slope for field stars and similar to the
values found for other young open clusters
The complex stellar populations in the background of open clusters in the third Galactic quadrant
No full textMulti-color photometry of the stellar populations in five fields in the third Galactic quadrant centred on the clusters NGC 2215, NGC 2354, Haffner 22, Ruprecht 11, and ESO489 SC01 is interpreted in terms of a warped and flared Galactic disk, without resort to an external entity such as the popular Monoceros or Canis Major overdensities. Except for NGC 2215, the clusters are poorly or unstudied previously. The data generate basic parameters for eachcluster, including the distribution of stars along the line of sight.We use star counts and photometric analysis, without recourse to Galactic-model-based predictions or interpretations, and confirms earlier results for NGC 2215 and NGC 2354. ESO489 SC01 is not a real cluster, while Haffner 22 is an overlooked cluster aged 2.5 Gyr. Conclusions for Ruprecht 11 are preliminary, evidence for a cluster being marginal. Fields surrounding the clusters show signaturesof young and intermediate-age stellar populations. The young population background to NGC 2354 and Ruprecht 11 lies 8?9 kpc from the Sun and 1 kpc below the formal Galactic plane, tracing a portion of the Norma-Cygnus arm, challenging Galactic models that adopt a sharp cut-off of the disk 1214 kpc from the Galactic center. The old population is metal poor with an age of 2 3 Gyr, resembling star clusters like Tombaugh 2 or NGC 2158. It has a large color spread and is difficult to locate precisely. Young and old populations followa pattern that depends critically on the vertical location of the thin and/or thick disk, and whether or not a particular line of sight intersects one, both, or none.Fil: Carraro, Giovanni. European Southern Observatory; ChileFil: Seleznev, Anton F.. Ural Federal University; RusiaFil: Baume, Gustavo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; ArgentinaFil: Turner D.. Saint Mary’s University; Canad
Estudio fotométrico de la región de IC 2944/IC 2948
Full text linkUtilizando una cámara de campo amplio (WFI/2.2m MPG/ ESO), se han obtenido varias imágenes profundas en las bandas V IC correspondientes a la zona de IC 2944 / IC 2948. Se ha realizado entonces fotometría PSF de las imágenes combinadas. De esta forma, se ha logrado estudiar el comportamiento de la secuencia principal inferior de la población estelar en esta zona. Se han complementado los datos con información de los objetos más brillantes disponible en diferentes trabajos previos y/o bases de datos públicas. El análisis preliminar de los datos obtenidos ha permitido estimar las características de la población estelar en esta dirección de la Galaxia.Fil: Rodriguez, Maria Jimena. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; ArgentinaFil: Panei, Jorge Alejandro. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; ArgentinaFil: Corti, Mariela Alejandra. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto Argentino de Radioastronomia (i); ArgentinaFil: Baume, Gustavo Luis. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; ArgentinaFil: Carraro, G.. Universidad de Chile. Facultad de Ciencias Fisicas y Matematicas; Chil
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