46 research outputs found
Grandes espectáculos celestes
Los mayores espectáculos que pueden observarse en los cielos de nuestro planeta son los eclipses totales de Sol y de Luna, las Auroras Polares y las Tormentas de Estrellas. Estos espectáculos celestes son el objetivo principal de las expediciones científicas que organiza la asociación Shelios, nacida a mediados de 1998, y que desde su creación ha organizado diversas expediciones a los lugares más remotos de la Tierra, como por ejemplo Turquía, Groenlandia, Teide, Zimbabwe, desierto de Australia, Sudáfrica, Antártida, desierto de Líbia o China.The greatest shows that can be seen in the skies of our planet are a total eclipse of the sun and moon, Polar Aurora and Stara storms. These celestial events are the main target of the scientific expeditions organized Shelios association, born in 1998, and since its creation has organized several expeditions to the remotest parts of Earth, such as Turkey, Greenland, Teide, Zimbabwe, desert of Australia, South Africa, Antarctic, desert of Libya or China
ATLAS-TEIDE: The next generations of ATLAS units for the Teide Observatory
In this work we present the design of the ATLAS unit (Asteroid
Terrestrial-impact Last Alert System) that will be installed at Teide
Observatory in Tenerife island (Spain). ATLAS-Teide will be built by the
Instituto de Astrofisica de Canarias (IAC) and will be operated as part of the
ATLAS network in the framework of an operation and science exploitation
agreement between the IAC and the ATLAS team at University of Hawaii.
ATLAS-Teide will be the first ATLAS unit based on commercial on the shelf
(COTS) components. Its design is modular, each module (building block) consist
of four Celestron RASA 11 telescopes that point to the same sky field, equipped
with QHY600PRO CMOS cameras on an equatorial Direct Drive mount. Each module is
equivalent to a 56cm effective diameter telescope and provides a 7.3 deg^2
field of view and a 1.26 arcsec/pix plate scale. ATLAS-Teide will consist of
four ATLAS modules in a roll-off roof building. This configuration allows to
cover the same sky area of the actual ATLAS telescopes.
The first ATLAS module was installed in November 2022 in an existing
clamshell at the TO. This module (ATLAS-P) is being used as a prototype to test
the system capabilities, develop the needed software (control, image
processing, etc.) and complete the fully integration of ATLAS-Teide in the
ATLAS network. The preliminary results of the tests are presented here, and the
benefits of the new ATLAS design are discussed.Comment: 5 pages, 8 figures, Conference pape
Spectroscopic and dynamical properties of comet C/2018 F4, likely a true average former member of the Oort cloud
The population of comets hosted by the Oort cloud is heterogeneous. Most
studies in this area focused on highly active objects, those with small
perihelion distances or examples of objects with peculiar physical properties
and/or unusual chemical compositions. This may have produced a biased sample of
Oort cloud comets in which the most common objects may be rare, particularly
those with perihelia well beyond the orbit of the Earth. Within this context,
the known Oort cloud comets may not be representative of the full sample. Here,
we study the spectral properties in the visible region and the cometary
activity of Comet C/2018 F4 (PANSTARRS). We also explore its orbital evolution
with the aim of understanding its origin within the context of known minor
bodies moving along nearly parabolic or hyperbolic paths. We present
observations obtained with the 10.4 m Gran Telescopio Canarias (GTC), derive
the spectral class and visible slope of C/2018 F4 and characterise its level of
cometary activity. Direct N-body simulations are carried out to explore its
orbital evolution. The absolute magnitude of C/2018 F4 is Hr=13.62+/-0.04.
Assuming a pV=0.04 its diameter is D<10.4 km. The object presents a conspicuous
coma, with a level of activity comparable to those of other comets observed at
similar heliocentric distances. Comet C/2018 F4 has a visible spectrum
consistent with that of an X-type asteroid, and has a spectral slope
S'=4.0+/-1.0 %/1000\AA and no evidence of hydration. The spectrum matches those
of well-studied primitive asteroids and comets. The analysis of its dynamical
evolution prior to discovery suggests that C/2018 F4 is not of extrasolar
origin. Although the present-day heliocentric orbit of C/2018 F4 is slightly
hyperbolic, its observational properties and past orbital evolution are
consistent with those of a dynamically old comet with an origin in the Oort
cloud.Comment: 6 pages, 5 figures. In pres
Spectroscopy of the Lens Galaxy of Q0957+561A,B. Implications of a possible central massive dark object
We present new long-slit William Herschel Telescope spectroscopic
observations of the lens galaxy G1 associated with the double-imaged QSO
0957+561A,B. The obtained central stellar velocity dispersion, sigma_l = 310
+/- 20 km/s, is in reasonable agreement with other measurements of this
dynamical parameter. Using all updated measurements of the stellar velocity
dispersion in the internal region of the galaxy (at angular separations < 1".5)
and a simple isotropic model, we discuss the mass of a possible central massive
dark object. It is found that the data of Falco et al. (1997) suggest the
existence of an extremely massive object of (0.5-2.1) x 10E10/h M_\odot (80%
confidence level), whereas the inclusion of very recent data (Tonry & Franx
1998, and this paper) substantially changes the results: the compact central
mass must be 6 x10E9/h M_\odot at the 90% confidence level. We note that,
taking into account all the available dynamical data, a compact nucleus with a
mass of 10E9/h M_\odot (best fit) cannot be ruled out.Comment: 20 pages, 10 figures ApJ, in pres
The INT Search for Metal-Poor Stars. Spectroscopic Observations and Classification via Artificial Neural Networks
With the dual aims of enlarging the list of extremely metal-poor stars
identified in the Galaxy, and boosting the numbers of moderately
metal-deficient stars in directions that sample the rotational properties of
the thick disk, we have used the 2.5m Isaac Newton Telescope and the
Intermediate Dispersion Spectrograph to carry out a survey of brighter
(primarily northern hemisphere) metal-poor candidates selected from the HK
objective-prism/interference-filter survey of Beers and collaborators. Over the
course of only three observing runs (15 nights) we have obtained
medium-resolution (resolving power ~ 2000) spectra for 1203 objects (V ~
11-15). Spectral absorption-line indices and radial velocities have been
measured for all of the candidates. Metallicities, quantified by [Fe/H], and
intrinsic (B-V)o colors have been estimated for 731 stars with effective
temperatures cooler than roughly 6500 K, making use of artificial neural
networks (ANNs), trained with spectral indices. We show that this method
performs as well as a previously explored Ca II K calibration technique, yet it
presents some practical advantages. Among the candidates in our sample, we
identify 195 stars with [Fe/H] <= -1.0, 67 stars with [Fe/H] <= -2.0, and 12
new stars with [Fe/H] <= -3.0. Although the EFECTIVE YIELD of metal-poor stars
in our sample is not as large as previous HK survey follow-up programs, the
rate of discovery per unit of telescope time is quite high.Comment: 27 pages (including 13 figures) + 6 tables (20 pages); uses aastex,
lscape and graphicx; to appear in A
'Round the Clock Observations of the Q0957+561 A,B Gravitationally Lensed Quasar
An observing campaign with 10 participating observatories has undertaken to
monitor the optical brightness of the Q0957 gravitationally lensed quasar for
10 consecutive nights in January 2000. The resulting A image brightness curve
has significant brightness fluctuations and makes a photometric prediction for
the B image light curve for a second campaign planned for 12-21 March 2001. The
ultimate purpose is to determine the gravitational lens time delay to a
fraction of an hour, and to seek evidence for rapid microlensing.Comment: 8 pages, AASTeX 4.0, accepted by the Astrophysical Journa
TOI-1135 b: A young hot Saturn-size planet orbiting a solar-type star
Despite the thousands of planets in orbit around stars known to date, the
mechanisms of planetary formation, migration, and atmospheric loss remain
unresolved. In this work, we confirm the planetary nature of a young
Saturn-size planet transiting a solar-type star every 8.03 d, TOI-1135\,b. The
age of the parent star is estimated to be in the interval of 125--1000 Myr
based on various activity and age indicators, including its stellar rotation
period of 5.13\,\,0.27 d and the intensity of photospheric lithium. We
obtained follow-up photometry and spectroscopy, including precise radial
velocity measurements using the CARMENES spectrograph, which together with the
TESS data allowed us to fully characterise the parent star and its planet. As
expected for its youth, the star is rather active and shows strong photometric
and spectroscopic variability correlating with its rotation period. We modelled
the stellar variability using Gaussian process regression. We measured the
planetary radius at 9.02\,\,0.23 R (0.81\,\,0.02
R) and determined a 3 upper limit of \,51.4
M (\,0.16 \,M) on the planetary mass by adopting a
circular orbit. Our results indicate that TOI-1135\,b is an inflated planet
less massive than Saturn or Jupiter but with a similar radius, which could be
in the process of losing its atmosphere by photoevaporation. This new young
planet occupies a region of the mass-radius diagram where older planets are
scarse, and it could be very helpful to understanding the lower frequency of
planets with sizes between Neptune and Saturn.Comment: Accepted in A&A. 18 pages, 15 figure
Around the Clock Observations of the Q0957+561 A,B Gravitationally Lensed Quasar II: Results for the second observing season
We report on an observing campaign in March 2001 to monitor the brightness of
the later arriving Q0957+561 B image in order to compare with the previously
published brightness observations of the (first arriving) A image. The 12
participating observatories provided 3543 image frames which we have analyzed
for brightness fluctuations. From our classical methods for time delay
determination, we find a 417.09 +/- 0.07 day time delay which should be free of
effects due to incomplete sampling. During the campaign period, the quasar
brightness was relatively constant and only small fluctuations were found; we
compare the structure function for the new data with structure function
estimates for the 1995--6 epoch, and show that the structure function is
statistically non-stationary. We also examine the data for any evidence of
correlated fluctuations at zero lag. We discuss the limits to our ability to
measure the cosmological time delay if the quasar's emitting surface is time
resolved, as seems likely.Comment: AAS LaTeX, 5 PostScript figure
Apophis planetary defense campaign
We describe results of a planetary defense exercise conducted during the close approach to Earth by the near-Earth asteroid (99942) Apophis during 2020 December–2021 March. The planetary defense community has been conducting observational campaigns since 2017 to test the operational readiness of the global planetary defense capabilities. These community-led global exercises were carried out with the support of NASA's Planetary Defense Coordination Office and the International Asteroid Warning Network. The Apophis campaign is the third in our series of planetary defense exercises. The goal of this campaign was to recover, track, and characterize Apophis as a potential impactor to exercise the planetary defense system including observations, hypothetical risk assessment and risk prediction, and hazard communication. Based on the campaign results, we present lessons learned about our ability to observe and model a potential impactor. Data products derived from astrometric observations were available for inclusion in our risk assessment model almost immediately, allowing real-time updates to the impact probability calculation and possible impact locations. An early NEOWISE diameter measurement provided a significant improvement in the uncertainty on the range of hypothetical impact outcomes. The availability of different characterization methods such as photometry, spectroscopy, and radar provided robustness to our ability to assess the potential impact risk