Bele pritlikavke opazovane s satelitom Gaia

magistrsko delo

Samo Ilc (Author), Tomaž Zwitter (Mentor)

Abstract

Satelit Gaia Evropske vesoljske agencije je 25. aprila 2018 objavil drugo javno objavo podatkov. V teh podatkih so meritve paralakse (oziroma razdalje), gibanja, sija in barve več kot milijarde zvezd v naši Galaksiji. Med opazovanimi viri so bile zaznane tudi bele pritlikavke. Bele pritlikavke so ostanki zvezd, v katerih jedrske reakcije ne potekajo več. So izredno gosti in še vedno vroči objekti, ki so po velikosti podobni Zemlji, maso pa imajo med 0,6 in 1,4 mase Sonca. Hidrostatično ravnovesje v teh objektih vzdržuje degeneriran elektronski plin, zato se ob stalni velikosti počasi ohlajajo in se s tem temnijo. Iz ogromne množice podatkov, ki jo je ustvaril satelit Gaia, se z HR-diagramom, torej primerjavo absolutne magnitude posameznega objekta z njegovo barvo,da izluščiti peščico objektov, ki ustrezajo lastnostim belih pritlikavk. Bele pritlikavke imajo na takem grafu specifično pozicijo, stran od zvezd glavne veje. Z omejitvijo merskih napak in šuma, je možno izluščiti $63414$ kanditatov za belo pritlikavko, kar je največji nabor belih pritlikavk do danes. Glavni vir informacije za te vire je njihova pozicija, ki se jo natančno določi. Iz tega se nato mapira bele pritlikavke po nočnem nebu, da se pridobi osnovna slika, kako so porazdeljene po Galaksiji. Na koncu z uporabo osnovnih fizikalnih modelov določi še splošne fizikalne količine kot so izsev, efektivna temperatura, radij, masa in starost, nato pa določimo še statistične lastnosti dobljenega vzorca.

Keywords

astronomija;zvezde;bele pritlikavke;satelit Gaia;HR-diagram;Galaksija;

Data

Language:	Slovenian
Year of publishing:	2019
Typology:	2.09 - Master's Thesis
Organization:	UL FMF - Faculty of Mathematics and Physics
Publisher:	[S. Ilc]
UDC:	524.354.7
COBISS:	3369060
Views:	462
Downloads:	124
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	White dwarfs observed by satellite Gaia
Secondary abstract:	Satellite Gaia of The European Space Agency made its second data release publicly available on April 25, 2018. In this data there are measurements of parallax (distance), motion, intensity and color of more than a billion stars in Milky way galaxy. Among the observed sources, white dwarfs were also detected. White dwarfs are the remants of stars in which there are no ongoing nuclear reactions. They are extremely dense and hot objects that are similar in size to Earth and have a mass between 0.6 and 1.4 masses of the Sun. The hydrostatic equilibrium in these objects is sustained by degenerate electron gas. That is why they slowly cool and dim at the constant size. From a huge data set created by the Gaia satellite, it is possible to extract a handful of objects that show the characteristics of white dwarfs. This can be obtained by drawing an HR-diagram by comparing the absolute magnitude of each object with its color. White dwarfs have a characteristic position on such a graph, away from the main sequence stars. By limiting the measurement error and the noise, $63414$ white dwarf candidated were extracted, which is the largest collection of white dwarfs to date. The main information for these sources is their position, that was precisely determined and then mapped out on the night sky, to gain a basic picture of their distribution in the Milky way galaxy. In the end, through basic physical models, general physical properties were computed, such as luminosity, effective temperature, radius, mass and age, which were then statistically processed.
Secondary keywords:	astronomy;stars;white dwarfs;Gaia satellite;HR-diagram;Milky way galaxy;
Type (COBISS):	Master's thesis/paper
Study programme:	0
Embargo end date (OpenAIRE):	1970-01-01
Thesis comment:	Univ. v Ljubljani, Fak. za matematiko in fiziko, Oddelek za fiziko
Pages:	72 str.
ID:	11221917