The Possibility of Detecting our Solar System through Astrometry

Searching for exoplanets with different methods has always been the focus of astronomers over the past few years.Among multiple planet detection techniques,astrometry stands out for its capability to accurately determine the orbital parameters of exoplanets.In this study,we examine the likelihood of extraterrestrial intelligent civilizations detecting planets in our solar system using the astrometry method.By conducting injection-recovery simulations,we investigate the detectability of the four giant planets in our solar system under different observing baselines and observational errors.Our findings indicate that extraterrestrial intelligence could detect and characterize all four giant planets,provided they are observed for a minimum of 90 yr with signal-noise ratios exceeding 1.For individual planets such as Jupiter,Saturn,and Neptune,a baseline that surpasses half of their orbital periods is necessary for detection.However,Uranus requires longer observing baselines since its orbital period is roughly half of that of Neptune.If the astrometry precision is equal to or better than 10μas,all 8707 stars located within30 pc of our solar system possess the potential to detect the four giant planets within 100 yr.Additionally,our prediction suggests that over 300 stars positioned within 10 pc from our solar system could detect our Earth if they achieve an astrometry precision of 0.3μas.

Searching for exoplanets with HEPS:I.detection probability of Earth-like planets in multiple systems

The astrometry method has great advantages in searching for exoplanets in the habitable zone around solar-like stars. However, the presence of multiple planets may cause a problem with degeneracy when trying to compute accurate planet parameters from observation data and reduce detectability. The degeneracy problem is extremely critical, especially in a space mission which has limited observation time and cadence. In this series of papers, we study the detectability of habitable Earth-mass planets in different types of multi-planet systems, aiming to find the most favorable targets for the potential space mission–Habitable ExoPlanet Survey(HEPS). In the first paper, we present an algorithm to find planets in the habitable zone around solar-like stars using astrometry. We find the detectability can be well described by planets' signal-to-noise ratio(SNR) and a defined parameter S = M2/(T1-T2)2, where M2 and T2are the mass and period of the second planet, respectively. T1 is the period of the planet in the habitable zone. The parameter S represents the influence of planetary architectures. We fit the detectability as a function of both the SNR of the planet in the habitable zone and the parameter S. An Earth-like planet in a habitable zone is harder to detect(with detectability PHP< 80%) in a system with a hot Jupiter or warm Jupiter(within2 AU), in which the parameter S is large. These results can be used in target selections and to determine the priority of target stars for HEPS, especially when we select and rank nearby planet hosts with a single planet.

Effect of safflower injection on endoplasmic reticulum stress-induced apoptosis in rats with hypoxic pulmonary hypertension

Objective To explore the effects of safflower injection on prevention and treatment of hypoxic pulmonary hypertension and clarify the function of the endoplasmic reticulum stress apoptosis pathway during the process.Methods Thirty male SD rats were randomly grouped as normal control group,hypoxiahypercapnia group and hypoxia+safflower group.The latter two groups were put in the cabin with oxygen concentration ranged from 9% to 11% and carbon dioxide concentration from 5% to 6%.The pulmonary artery pressure and the index of right ventricular hypertrophy were determined after hypoxia exposure(8 h/d×28 d).Changes in morphology of lung tissue were observed by electron microscopy.To explore the possible mechanisms,we also detected apoptosis and apoptosis-related genes/proteins in lung tissue by TUNEL reactivity and PCR and Western blot.Results Compared with the normal control group,pulmonary artery pressure and the index of right ventricular hypertrophy in hypoxia group were 45% and 33.4% higher,respectively.Tiny blood vessel wall of lungs was thickened and edema,and proliferation of collagen fibers was obvious under the electron microscope.TUNEL staining of apoptotic cells in lung tissues showed more high brightness green fluorescence(+～++),but less green fluorescence showed in the pulmonary vascular smooth muscle cell layer,and apoptosis index(AI) value was 150% higher;gene and protein expression levels of endoplasmic reticulum stress pathway were increased.Compared with hypoxia-hypercapnia group,pulmonary artery pressure and the index of right ventricular hypertrophy in the hypoxia+safflower group were 18% and 15.6% lower,respectively;collagen fibers were decreased,and smooth muscle cells and epithelial cells were got apoptotic-like changes under the electron microscope.TUNEL staining of apoptotic cells in lung tissues showed brighter green fluorescence(++～+++);the high brightness green fluorescence showed in pulmonary vascular smooth muscle cell layer,and apoptotic index(AI) value was 40% higher;gene and protein expressions of endoplasmic reticulum stress pathway were significantly upregulated.Conclusion Our findings demonstrate that safflower injection could activate endoplasmic reticulum stressinduced apoptosis and especially promote apoptosis in pulmonary vascular smooth muscle cells.