Broad-band (ultraviolet to near-infrared) observations of the intense gamma ray burst GRB 990123 ... more Broad-band (ultraviolet to near-infrared) observations of the intense gamma ray burst GRB 990123 started ∼8.5 hours after the event and continued until 18 February 1999. When combined with other data, in particular from the Robotic Telescope and Transient Source Experiment (ROTSE) and the Hubble Space Telescope (HST), evidence emerges for a smoothly declining light curve, suggesting some color dependence that could be related to a cooling break passing the ultraviolet-optical band at about 1 day after the high-energy event. The steeper decline rate seen after 1.5 to 2 days may be evidence for a collimated jet pointing toward the observer.
Bibliografía A. Velocidad radial y dispersión de velocidades centrales B. Gradientes de velocidad... more Bibliografía A. Velocidad radial y dispersión de velocidades centrales B. Gradientes de velocidad radial y dispersión de velocidades C. Gradientes deíndices
We report the discovery and characterization of TOI-1759 b, a temperate (400 K) sub-Neptune-sized... more We report the discovery and characterization of TOI-1759 b, a temperate (400 K) sub-Neptune-sized exoplanet orbiting the M dwarf TOI-1759 (TIC 408636441). TOI-1759 b was observed by TESS to transit in Sectors 16, 17, and 24, with only one transit observed per sector, creating an ambiguity regarding the orbital period of the planet candidate. Ground-based photometric observations, combined with radial-velocity measurements obtained with the CARMENES spectrograph, confirm an actual period of 18.85019 ± 0.00014 days. A joint analysis of all available photometry and radial velocities reveals a radius of 3.17 ± 0.10 R ⊕ and a mass of 10.8 ± 1.5 M ⊕. Combining this with the stellar properties derived for TOI-1759 (R ⋆ = 0.597 ± 0.015 R ⊙; M ⋆ = 0.606 ± 0.020 M ⊙; T eff = 4065 ± 51 K), we compute a transmission spectroscopic metric (TSM) value of over 80 for the planet, making it a good target for transmission spectroscopy studies. TOI-1759 b is among the top five temperate, small exoplane...
We present new measurements of central line-strength indices (namely Mg2, 〈Fe〉, and Hβ) and gradi... more We present new measurements of central line-strength indices (namely Mg2, 〈Fe〉, and Hβ) and gradients for a sample of 6 bright spheroidal galaxies (Sph’s) in the Virgo cluster. Comparison with similar measurements for elliptical galaxies (E’s), galactic globular clusters (GGC’s), and stellar population models yield the following results: (1) In contrast with bright E’s, bright Sph’s are consistent with solar abundance [Mg/Fe] ratios; (2) Bright Sph’s exhibit metallicities ranging from values typical for metal-rich GGC’s to those for E’s; (3) Although absolute mean ages are quite model dependent, we find evidence that the stellar populations of some (if not all) Sph’s look significantly younger than GGC’s; and (4) Mg2 gradients of bright Sph’s are significantly shallower than those of E galaxies. We conclude that the dichotomy found in the structural properties of Sph and E galaxies is also observed in their stellar populations. A tentative interpretation in terms of differences in s...
Stellar Populations and Morphologies of the galaxies in the core of Abell2218
We present a study of the stellar populations and morphologies of galaxies in the core of the gal... more We present a study of the stellar populations and morphologies of galaxies in the core of the galaxy cluster Abell 2218. Integral field spectroscopy (IFS) observations were performed using PMAS in the PPAK mode covering a field-of-view of~ 74”× 64” centred in the core of the cluster, in order to obtain spectroscopy of an unbiased sample of cluster galaxies down to I< 22.4 mags. Forty-three objects were detected in the IFS data, 28 of them galaxies at the redshift of the cluster (17 with previously unknown redshift). Individual ...
[16]“The evolution of eary-type, red galaxies with the GEMS survey: Luminosity-size and stellar m... more [16]“The evolution of eary-type, red galaxies with the GEMS survey: Luminosity-size and stellar mass-size relations since z~ 1” DH McIntosh, EF Bell, H.-W. Rix, et al., 2005, ApJ, 632, 191 [17]“Decoupling the host and nuclear spectra of type I AGNs using integral field spectroscopy: A test on 3C 120” SF Sánchez, B. Garcia-Lorenzo, K., Jahnke; E., Mediavilla, JI González-Serrano, L. Christensen, L. Wisotzki, 2006, NewAR, 49, 501 [18]“The giant Lyalpha nebula associated with az= 2.5 radio galaxy” M., Villar-Martın, SF Sánchez, R. ...
Debido a la importancia de los gradientes de líneas de absorción en el estudio de la formación y ... more Debido a la importancia de los gradientes de líneas de absorción en el estudio de la formación y evolución secular de las galaxias elípticas, se propone obtener mapas de intensidad de líneas de absorción en galaxias elípticas cercanas haciendo uso de OSIRIS y el GTC. Los métodos para observar e interpretar estos mapas están guiados y optimizados mediante sofisticados modelos de síntesis de poblaciones estelares, los cuales permitirán derivar los parámetros característicos de las poblaciones estelares como son las metalicidades, edades, abundancias relativas de elementos y la Función Inicial de Masas. Nuestro principal objetivo es acotar los escenarios de formación y evolución de las galaxias elípticas mediante la información obtenida a partir de la distribución global y radial de sus poblaciones estelares.
Poblaciones estelares en galaxias elípticas enanas
Se han estudiado las poblaciones estelares de 42 galaxias elípticas enanas (dEs), 8 gigantes y 7 ... more Se han estudiado las poblaciones estelares de 42 galaxias elípticas enanas (dEs), 8 gigantes y 7 compactas del cúmulo de Virgo con observaciones espectroscópicas que han permitido medir la velocidad radial y dispersión de velocidades. Por primera vez se han medido sus gradientes en una muestra significativa de elípticas enanas, encontrando que no todas las dEs están soportadas por la anisotropía en la distribución de velocidades. Una fracción importante de ellas presentan altas velocidades de rotación. Los índices de Lick, en el centro de las dEs, comparten la relación encontrada con la dispersión de velocidades central para las gigantes, con diferencias solo significativas para el magnesio. Las zonas ocupadas en las predicciones de los modelos de síntesis, a diferencia de las elípticas gigantes, no dependen del índice metálico utilizado. Por lo tanto, las edades y metalicidades obtenidas para la dEs muestran menor dependencia de los índices elegidos y las abundancias relativas entr...
The candidate star for the occultation analysed in this paper was discovered during a systematic ... more The candidate star for the occultation analysed in this paper was discovered during a systematic search for candidate stars to be occulted by Pluto and other several large TNOs in 2008-15, conducted at the 2.2m telescope of the European Southern Observatory 15. It revealed the star NOMAD1 0856-0015072 with V ∼17.1, R∼16.9 as a potential candidate for an occultation by Eris on the night of 6 November 2010 around 02:20 UT. Initial possible zones of visibility included western Europe and Africa, as well as north and south America (see www.lesia.obspm.fr/perso/bruno-sicardy/predic occn 10/Eris 2010). This was the unique event predicted for 2010. Actually, stellar occultations by Eris remain rare events as the dwarf planet moves far away from the galactic plane, in poor stellar fields in Cetus constellation (no event involving Eris is expected in our list before 2013).
We summarize the main properties of the extended UV (XUV) emission found in roughly 30% of the ne... more We summarize the main properties of the extended UV (XUV) emission found in roughly 30% of the nearby spiral galaxies observed by the GALEX satellite. Two different classes of XUV disks are identified, the Type 1 XUV disks where significant, structured UV-bright features are found beyond the classical azimuthally-averaged star-formation threshold, and the Type 2 XUV disks, which are characterized by very extended (seven times the area where most of the stellar mass is found), blue [(FUV−K)<5 mag] outer disks. These latter disks are extreme examples of galaxies growing inside-out. The few XUV disks studied in detail to date are rich in HI but relatively poor in molecular gas, have stellar populations with luminosity-weighted ages of ∼1 Gyr, and ionizedgas metal abundances of ∼Z ⊙ /10. As part of the CAHA-XUV project we are in the process of obtaining deep multi-wavelength imaging and spectroscopy of 65 XUV-disk galaxies so to determine whether or not these properties are common among XUV disks.
Broad-band (ultraviolet to near-infrared) observations of the intense gamma ray burst GRB 990123 ... more Broad-band (ultraviolet to near-infrared) observations of the intense gamma ray burst GRB 990123 started ∼8.5 hours after the event and continued until 18 February 1999. When combined with other data, in particular from the Robotic Telescope and Transient Source Experiment (ROTSE) and the Hubble Space Telescope (HST), evidence emerges for a smoothly declining light curve, suggesting some color dependence that could be related to a cooling break passing the ultraviolet-optical band at about 1 day after the high-energy event. The steeper decline rate seen after 1.5 to 2 days may be evidence for a collimated jet pointing toward the observer.
Bibliografía A. Velocidad radial y dispersión de velocidades centrales B. Gradientes de velocidad... more Bibliografía A. Velocidad radial y dispersión de velocidades centrales B. Gradientes de velocidad radial y dispersión de velocidades C. Gradientes deíndices
We report the discovery and characterization of TOI-1759 b, a temperate (400 K) sub-Neptune-sized... more We report the discovery and characterization of TOI-1759 b, a temperate (400 K) sub-Neptune-sized exoplanet orbiting the M dwarf TOI-1759 (TIC 408636441). TOI-1759 b was observed by TESS to transit in Sectors 16, 17, and 24, with only one transit observed per sector, creating an ambiguity regarding the orbital period of the planet candidate. Ground-based photometric observations, combined with radial-velocity measurements obtained with the CARMENES spectrograph, confirm an actual period of 18.85019 ± 0.00014 days. A joint analysis of all available photometry and radial velocities reveals a radius of 3.17 ± 0.10 R ⊕ and a mass of 10.8 ± 1.5 M ⊕. Combining this with the stellar properties derived for TOI-1759 (R ⋆ = 0.597 ± 0.015 R ⊙; M ⋆ = 0.606 ± 0.020 M ⊙; T eff = 4065 ± 51 K), we compute a transmission spectroscopic metric (TSM) value of over 80 for the planet, making it a good target for transmission spectroscopy studies. TOI-1759 b is among the top five temperate, small exoplane...
We present new measurements of central line-strength indices (namely Mg2, 〈Fe〉, and Hβ) and gradi... more We present new measurements of central line-strength indices (namely Mg2, 〈Fe〉, and Hβ) and gradients for a sample of 6 bright spheroidal galaxies (Sph’s) in the Virgo cluster. Comparison with similar measurements for elliptical galaxies (E’s), galactic globular clusters (GGC’s), and stellar population models yield the following results: (1) In contrast with bright E’s, bright Sph’s are consistent with solar abundance [Mg/Fe] ratios; (2) Bright Sph’s exhibit metallicities ranging from values typical for metal-rich GGC’s to those for E’s; (3) Although absolute mean ages are quite model dependent, we find evidence that the stellar populations of some (if not all) Sph’s look significantly younger than GGC’s; and (4) Mg2 gradients of bright Sph’s are significantly shallower than those of E galaxies. We conclude that the dichotomy found in the structural properties of Sph and E galaxies is also observed in their stellar populations. A tentative interpretation in terms of differences in s...
Stellar Populations and Morphologies of the galaxies in the core of Abell2218
We present a study of the stellar populations and morphologies of galaxies in the core of the gal... more We present a study of the stellar populations and morphologies of galaxies in the core of the galaxy cluster Abell 2218. Integral field spectroscopy (IFS) observations were performed using PMAS in the PPAK mode covering a field-of-view of~ 74”× 64” centred in the core of the cluster, in order to obtain spectroscopy of an unbiased sample of cluster galaxies down to I< 22.4 mags. Forty-three objects were detected in the IFS data, 28 of them galaxies at the redshift of the cluster (17 with previously unknown redshift). Individual ...
[16]“The evolution of eary-type, red galaxies with the GEMS survey: Luminosity-size and stellar m... more [16]“The evolution of eary-type, red galaxies with the GEMS survey: Luminosity-size and stellar mass-size relations since z~ 1” DH McIntosh, EF Bell, H.-W. Rix, et al., 2005, ApJ, 632, 191 [17]“Decoupling the host and nuclear spectra of type I AGNs using integral field spectroscopy: A test on 3C 120” SF Sánchez, B. Garcia-Lorenzo, K., Jahnke; E., Mediavilla, JI González-Serrano, L. Christensen, L. Wisotzki, 2006, NewAR, 49, 501 [18]“The giant Lyalpha nebula associated with az= 2.5 radio galaxy” M., Villar-Martın, SF Sánchez, R. ...
Debido a la importancia de los gradientes de líneas de absorción en el estudio de la formación y ... more Debido a la importancia de los gradientes de líneas de absorción en el estudio de la formación y evolución secular de las galaxias elípticas, se propone obtener mapas de intensidad de líneas de absorción en galaxias elípticas cercanas haciendo uso de OSIRIS y el GTC. Los métodos para observar e interpretar estos mapas están guiados y optimizados mediante sofisticados modelos de síntesis de poblaciones estelares, los cuales permitirán derivar los parámetros característicos de las poblaciones estelares como son las metalicidades, edades, abundancias relativas de elementos y la Función Inicial de Masas. Nuestro principal objetivo es acotar los escenarios de formación y evolución de las galaxias elípticas mediante la información obtenida a partir de la distribución global y radial de sus poblaciones estelares.
Poblaciones estelares en galaxias elípticas enanas
Se han estudiado las poblaciones estelares de 42 galaxias elípticas enanas (dEs), 8 gigantes y 7 ... more Se han estudiado las poblaciones estelares de 42 galaxias elípticas enanas (dEs), 8 gigantes y 7 compactas del cúmulo de Virgo con observaciones espectroscópicas que han permitido medir la velocidad radial y dispersión de velocidades. Por primera vez se han medido sus gradientes en una muestra significativa de elípticas enanas, encontrando que no todas las dEs están soportadas por la anisotropía en la distribución de velocidades. Una fracción importante de ellas presentan altas velocidades de rotación. Los índices de Lick, en el centro de las dEs, comparten la relación encontrada con la dispersión de velocidades central para las gigantes, con diferencias solo significativas para el magnesio. Las zonas ocupadas en las predicciones de los modelos de síntesis, a diferencia de las elípticas gigantes, no dependen del índice metálico utilizado. Por lo tanto, las edades y metalicidades obtenidas para la dEs muestran menor dependencia de los índices elegidos y las abundancias relativas entr...
The candidate star for the occultation analysed in this paper was discovered during a systematic ... more The candidate star for the occultation analysed in this paper was discovered during a systematic search for candidate stars to be occulted by Pluto and other several large TNOs in 2008-15, conducted at the 2.2m telescope of the European Southern Observatory 15. It revealed the star NOMAD1 0856-0015072 with V ∼17.1, R∼16.9 as a potential candidate for an occultation by Eris on the night of 6 November 2010 around 02:20 UT. Initial possible zones of visibility included western Europe and Africa, as well as north and south America (see www.lesia.obspm.fr/perso/bruno-sicardy/predic occn 10/Eris 2010). This was the unique event predicted for 2010. Actually, stellar occultations by Eris remain rare events as the dwarf planet moves far away from the galactic plane, in poor stellar fields in Cetus constellation (no event involving Eris is expected in our list before 2013).
We summarize the main properties of the extended UV (XUV) emission found in roughly 30% of the ne... more We summarize the main properties of the extended UV (XUV) emission found in roughly 30% of the nearby spiral galaxies observed by the GALEX satellite. Two different classes of XUV disks are identified, the Type 1 XUV disks where significant, structured UV-bright features are found beyond the classical azimuthally-averaged star-formation threshold, and the Type 2 XUV disks, which are characterized by very extended (seven times the area where most of the stellar mass is found), blue [(FUV−K)<5 mag] outer disks. These latter disks are extreme examples of galaxies growing inside-out. The few XUV disks studied in detail to date are rich in HI but relatively poor in molecular gas, have stellar populations with luminosity-weighted ages of ∼1 Gyr, and ionizedgas metal abundances of ∼Z ⊙ /10. As part of the CAHA-XUV project we are in the process of obtaining deep multi-wavelength imaging and spectroscopy of 65 XUV-disk galaxies so to determine whether or not these properties are common among XUV disks.
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