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The ability of p53 to promote apoptosis in response to mitogenic oncogenes appears to be critical for its tumor suppressor function. Caspase-9 and its cofactor Apaf-1 were found to be essential downstream components of p53 in Myc-induced apoptosis. Like p53 null cells, mouse embryo fibroblast cells deficient in Apaf-1 and caspase-9, and expressing c-Myc, were resistant to apoptotic stimuli that mimic conditions in developing tumors. Inactivation of Apaf-1 or caspase-9 substituted for p53 loss in promoting the oncogenic transformation of Myc-expressing cells. These results imply a role for Apaf-1 and caspase-9 in controlling tumor development.

Context. Known Mars trojans could be primordial small bodies that have remained in their present-day orbits for the age of the Solar System. Their orbital distribution is strongly asymmetric; there are over a dozen objects at the L5 point and just one at L4, (121514) 1999 UJ7. Most L5 trojans appear to form a collision-induced asteroid cluster, known as the Eureka family. Asteroid 2023 FW14 was recently discovered and it has a robust orbit determination that may be consistent with a Mars trojan status. Aims. Our aim is determine the nature and dynamical properties of 2023 FW14. Methods. We carried out an observational study of 2023 FW14 to derive its spectral class using the OSIRIS camera spectrograph at the 10.4 m Gran Telescopio Canarias. We investigated its possible trojan resonance with Mars using direct N-body simulations. Results. The reflectance spectrum of 2023 FW14 is not compatible with the olivine-rich composition of the Eureka family; it also does not resemble the composition of the Moon, although (101429) 1998 VF31 does. The Eureka family and 101429 are at the L5 point. The spectrum of 2023 FW14 is also different from two out of the three spectra in the literature of the other known L4 trojan, 121514, which are of C-type. The visible spectrum of 2023 FW14 is consistent with that of an X-type asteroid, as is the third spectrum of 121514. Our calculations confirm that 2023 FW14 is the second known L4 Mars trojan although it is unlikely to be primordial; it may remain in its present-day tadpole path for several million years before transferring to a Mars-crossing orbit. It might be a fragment of 121514, but a capture scenario seems more likely. Conclusions. The discovery of 2023 FW14 suggests that regular Mars-crossing asteroids can be captured as temporary Mars trojans.

In 2018, Solar Cycle 24 entered into a solar minimum phase. During this period, 11 million zenithal night sky brightness (NSB) data were collected at different dark sites around the planet, including astronomical observatories and natural protected areas, with identical broadband Telescope Encoder and Sky Sensor photometers (based on the Unihedron Sky Quality Meter TSL237 sensor). A detailed observational review of the multiple effects that contribute to the NSB measurement has been conducted with optimal filters designed to avoid brightening effects by the Sun, the Moon, clouds, and other astronomical sources (the Galaxy and zodiacal light). The natural NSB has been calculated from the percentiles for 44 different photometers by applying these new filters. The pristine night sky was measured to change with an amplitude of 0.1 mag/arcsec\\(^2\\) in all the photometers, which is suggested to be due to NSB variations on scales of up to months and to be compatible with semiannual oscillations. We report the systematic observation of short-time variations in NSB on the vast majority of the nights and find these to be related to airglow events forming above the mesosphere.

Context. The Arjuna asteroid belt is loosely defined as a diverse group of small asteroids that follow dynamically cold, Earth-like orbits. Most of them are not actively engaged in resonant, co-orbital behavior with Earth. Some of them experience temporary but recurrent horseshoe episodes. Objects in horseshoe paths tend to approach Earth at a low velocity, leading to captures as Earth's temporary satellites or mini-moons. Four such objects have already been identified: 1991 VG, 2006 RH120, 2020 CD3, and 2022 NX1. Here, we focus on 2023 FY3, a recent finding, the trajectory of which might have a co-orbital status and perhaps lead to temporary captures. Aims. We want to determine the physical properties of 2023 FY3 and explore its dynamical evolution. Methods. We carried out an observational study of 2023 FY3 using the OSIRIS camera spectrograph at the 10.4 m Gran Telescopio Canarias, to derive its spectral class, and time-series photometry obtained with QHY411M cameras and two units of the Two-meter Twin Telescope to investigate its rotational state. N-body simulations were also performed to examine its possible resonant behavior. Results. The visible reflectance spectrum of 2023 FY3 is consistent with that of an S-type asteroid; its light curve gives a rotation period of 9.3\\(\\pm\\)0.6 min, with an amplitude of 0.48\\(\\pm\\)0.13 mag. We confirm that 2023 FY3 roams the edge of Earth's co-orbital space. Conclusions. Arjuna 2023 FY3, an S-type asteroid and fast rotator, currently exhibits horseshoe-like resonant behavior and in the past experienced mini-moon engagements of the temporarily captured flyby type that may repeat in the future. The spectral type result further confirms that mini-moons are a diverse population in terms of surface composition.

Near-Earth asteroids (NEAs) that may evolve into impactors deserve detailed threat assessment studies. Early physical characterization of a would-be impactor may help in optimizing impact mitigation plans. We first detected NEA 2023~DZ\\(_{2}\\) on 27--February--2023. After that, it was found to have a Minimum Orbit Intersection Distance (MOID) with Earth of 0.00005~au as well as an unusually high initial probability of becoming a near-term (in 2026) impactor. We aim to perform a rapid but consistent dynamical and physical characterization of 2023~DZ\\(_{2}\\) as an example of a key response to mitigate the consequences of a potential impact. We use a multi-pronged approach, drawing from various methods (observational/computational) and techniques (spectroscopy/photometry from multiple instruments), and bringing the data together to perform a rapid and robust threat assessment.} The visible reflectance spectrum of 2023~DZ\\(_{2}\\) is consistent with that of an X-type asteroid. Light curves of this object obtained on two different nights give a rotation period \\(P\\)=6.2743\\(\\pm\\)0.0005 min with an amplitude \\(A\\)=0.57\\(\\pm\\)0.14~mag. We confirm that although its MOID is among the smallest known, 2023~DZ\\(_{2}\\) will not impact Earth in the foreseeable future as a result of secular near-resonant behaviour. Our investigation shows that coordinated observation and interpretation of disparate data provides a robust approach from discovery to threat assessment when a virtual impactor is identified. We prove that critical information can be obtained within a few days after the announcement of the potential impactor.

Context. Centaurs go around the Sun between the orbits of Jupiter and Neptune. Only a fraction of the known centaurs have been found to display comet-like features. Comet 29P/Schwassmann-Wachmann 1 is the most remarkable active centaur. It orbits the Sun just beyond Jupiter in a nearly circular path. Only a handful of known objects follow similar trajectories. Aims. We present photometric observations of 2020 MK4, a recently found centaur with an orbit not too different from that of 29P, and we perform a preliminary exploration of its dynamical evolution. Methods. We analyzed broadband Cousins R and Sloan g', r', and i' images of 2020 MK4 acquired with the Jacobus Kapteyn Telescope and the IAC80 telescope to search for cometary-like activity, and to derive its surface colors and size. Its orbital evolution was studied using direct N-body simulations. Results. Centaur 2020 MK4 is neutral-gray in color and has a faint, compact cometary-like coma. The values of its color indexes, (g'-r')=0.42+/-0.04 and (r'-i')=0.17+/-0.04, are similar to the solar ones. A lower limit for the absolute magnitude of the nucleus is Hg=11.30+/-0.03 mag which, for an albedo in the range of 0.1-0.04, gives an upper limit for its size in the interval (23, 37) km. Its orbital evolution is very chaotic and 2020 MK4 may be ejected from the Solar System during the next 200 kyr. Comet 29P experienced relatively close flybys with 2020 MK4 in the past, sometimes when they were temporary Jovian satellites. Conclusions. We confirm the presence of a coma of material around a central nucleus. Its surface colors place this centaur among the most extreme members of the gray group. Although its past, present, and future dynamical evolution resembles that of 29P, more data are required to confirm or reject a possible connection between the two objects and perhaps others.

We present an observational and numerical study of the borderline hyperbolic comet C/2021 O3 (PANSTARRS) performed during its recent passage through the inner Solar system. Our observations were carried out at OASI and SOAR between 2021 October and 2022 January, and reveal a low level of activity relative to which was measured for other long-period comets. In addition, we observed a decrease in brightness as the comet got closer to the Sun. Our photometric data, obtained as C/2021 O3 approached perihelion on 2022 April 21, show that the comet was much less active than what is usually expected in the cases of long-period comets, with \\(Af\\rho\\) values more in line with those of short-period comets (specifically, the Jupiter Family Comets). On the other hand, the observed increase in the value of the spectral slope as the amount of dust in the coma decreased could indicate that the smaller dust particles were being dispersed from the coma by radiation pressure faster than they were injected by possible sublimation jets. The analysis of its orbital evolution suggests that C/2021 O3 could be a dynamically old comet, or perhaps a new one masquerading as a dynamically old comet, with a likely origin in the Solar system.

In the framework of the Visible NEAs Observations Survey (ViNOS) that uses several telescopes at the Canary Islands observatories since 2018, we observed two super fast rotator NEAs, 2021 NY\\(_1\\) and 2022 AB. We obtained photometry and spectrophotometry of both targets and visible spectroscopy of 2022 AB. Light curves of 2021 NY\\(_1\\) obtained in 4 different nights between Sept. 30 and Oct. 16, 2021 return a rotation period \\(P=13.3449\\pm0.0013\\) minutes and a light curve amplitude \\(A = 1.00\\) mag. We found that 2021 NY\\(_1\\) is a very elongated super fast rotator with an axis ratio \\(a/b \\ge 3.6\\). We also report colours \\((g-r) = 0.664 \\pm 0.013\\), \\((r-i) = 0.186 \\pm 0.013\\), and \\((i-z_s) = -0.117 \\pm 0.012\\) mag. These are compatible with an S-type asteroid. The light curves of 2022 AB obtained on Jan. 5 and Jan. 8, 2021 show a rotation period \\(P=3.0304\\pm0.0008\\) minutes, with amplitudes \\(A = 0.52\\) and \\(A =0.54\\) mag. 2022 AB is also an elongated object with axis ratio \\(a/b \\ge 1.6\\). The obtained colours are \\((g-r) = 0.400 \\pm 0.017\\), \\((r-i) = 0.133 \\pm 0.017\\), and \\((i-z_s) = 0.093 \\pm 0.016\\). These colours are similar to those of the X-types, but with an unusually high \\((g-r)\\) value. Spectra obtained on Jan. 12 and Jan. 14, 2022, are consistent with the reported colours. The spectral upturn over the 0.4 - 0.6 \\(\\mu m \\) region of 2022 AB does not fit with any known asteroid taxonomical class or meteorite spectrum, confirming its unusual surface properties.