Are the planets there? The case of the HD34445 planetary system----中国科学院紫金山天文台

Seminar Title	1: Are the planets there？The case of the HD34445 planetary system
	2: On the enlargement of habitable zones around binary stars in hostile environments
Speaker:	Dr. Nikolaos Georgakarakos

Affiliation:	(NYUAD)

When	Monday afternoon, Oct. 21, 14:00 p.m.

Where:	Room 302 No.3 building , Xianlin campus (PMO, CAS)
	Welcome to Attend

	( PMO Academic Committee & Academic Circulating committee)

Abstract:

　　1:In 2017, HD34445 already known to have a planet, was announced to host another five planets. It is a dense planetary system with some of its planets having separations of fractions of an au. Here, we investigate the dynamical stability of the six planet system in order to check the validity of the orbital solution announced. We achieve that by a series of numerical experiments, where the dynamical stability of the system is tested on different timescales. By varying the orbital elements and masses of the system within the error ranges provided, we find that for a large area of the parameter space we can produce stable configurations and therefore conclude it is very likely that the HD 34445 planetary system is real. Some discussion about the potential habitability of the system is also done.

2: Theoretical studies and observations over the past years have shown that not only is possible to form planets in binary systems but also that double stars can be hosts to habitable worlds. Water is a fundamental element for developing and sustaining life as we know it. Whether a planet can provide favourable conditions for retaining water on its surface depends on many things.In a single star-planet system, habitability is a rather complex matter to be resolved, as there is a large number of factors that need to be taken into consideration. The situation gets even more perplexed when the planet resides in a stellar binary, either in a circumstellar or a circumbinary orbit.In this work We investigate the hypothesis that the size of the habitable zone around hardened binaries in dense star-forming regions increases. Our results indicate that this hypothesis is essentially incorrect. Although certain binary star configurations allow extended habitable zones, such set-ups typically require all orbits in a system to be nearly circular.In all other cases planets can only remain habitable if they display an extraordinarily high climate inertia.