Advanced

Assessing the Improvements GAIA-DR1 Will Bring to Dynamical Astronomy

Prgomet, Mateo LU (2017) In Lund Observatory Examensarbeten ASTK02 20171
Lund Observatory
Abstract
The first part of this thesis deals with the dynamical estimation of the Oort constants using proper motions and parallaxes provided from the Gaia-DR1 TGAS catalogue. The photometric information was provided by the 2MASS catalogue. The Oort constants calculated from the TGAS catalogue are compared to those obtained from the original Hipparcos catalogue in order to attempt to estimate how well Gaia-DR1 performs. A least squares approach was implemented to calculate the Oort constants. This routine contained seven parameters where the stellar LSR velocity components were included as well. The overall trend seems to be such that the TGAS catalogue can provide meaningful and potentially better results compared to that of the Hipparcos... (More)
The first part of this thesis deals with the dynamical estimation of the Oort constants using proper motions and parallaxes provided from the Gaia-DR1 TGAS catalogue. The photometric information was provided by the 2MASS catalogue. The Oort constants calculated from the TGAS catalogue are compared to those obtained from the original Hipparcos catalogue in order to attempt to estimate how well Gaia-DR1 performs. A least squares approach was implemented to calculate the Oort constants. This routine contained seven parameters where the stellar LSR velocity components were included as well. The overall trend seems to be such that the TGAS catalogue can provide meaningful and potentially better results compared to that of the Hipparcos catalogue if the study is not sensitive to a catalogue that is colour incomplete. TGAS worked fairly well in the determination of the Oort constants mainly due to its large sample size, giving it a statistical edge over the Hipparcos catalogue.

In the second part of the thesis the local mass density, ρ₀, was determined using tracer star populations for two catalogues. The first one was the original Hipparcos catalogue where the data was propagated to the year 2015. The second catalogue was a combination of Hipparcos stars obtained from both the TGAS and the propagated HIP catalogues. This was done in order to avoid the incompleteness issue that resulted after the creation of the TGAS catalogue.

The estimated local mass density from the propagated Hipparcos catalogue was ρ₀ = 0.112 ± 0.009 solar masses per pc³ while the combined TGAS sample got ρ₀ = 0.113 ± 0.006 solar masses per pc³. This result implies that the TGAS catalogue is slightly better compared to the HIP catalogue in performance since it provides with lower formal errors.

Based on the results of the two dynamical estimations performed, the TGAS catalogue can be seen as marginally better when compared to the HIP catalogue. In addition, the formal errors resulting from the calculations using the TGAS catalogue are better compared to those obtained using the HIP catalogue. The formal errors are especially good when dynamically estimating the Oort constants since so many stars are included in the calculations. It is, however, difficult to estimate the performance of the complete Gaia catalogue by simply considering the first data release. The release of Gaia-DR2 will hopefully resolve the questions surrounding the performance of the Gaia catalogue. (Less)
Popular Abstract (Swedish)
Genom att observera och intervjua invånarna i Lund, kan man erhålla mycket information om historien och infrastrukturen för staden. Detta tyder på en särskilt självklar princip; om man studerar de mindre beståndsdelarna av ett system, så kan man erhålla egenskaper som är gällande för systemet i helhet. Detta är precis vad dagens astronomer utnyttjar för att lära sig mera om vårt universum. De minsta beståndsdelarna i en galax är stjärnorna, och genom att samla information för alla dessa så kan man erhålla detaljer kring galaxens utveckling och struktur. Gaia uppdraget har precis detta i åtanke. I detta väldigt ambitiösa projekt så hoppas man kunna kartlägga Vintergatan genom att ta mätningar för ungefär en miljard stjärnor. Med denna... (More)
Genom att observera och intervjua invånarna i Lund, kan man erhålla mycket information om historien och infrastrukturen för staden. Detta tyder på en särskilt självklar princip; om man studerar de mindre beståndsdelarna av ett system, så kan man erhålla egenskaper som är gällande för systemet i helhet. Detta är precis vad dagens astronomer utnyttjar för att lära sig mera om vårt universum. De minsta beståndsdelarna i en galax är stjärnorna, och genom att samla information för alla dessa så kan man erhålla detaljer kring galaxens utveckling och struktur. Gaia uppdraget har precis detta i åtanke. I detta väldigt ambitiösa projekt så hoppas man kunna kartlägga Vintergatan genom att ta mätningar för ungefär en miljard stjärnor. Med denna moderna kartläggningen av galaxen så hoppas man kunna upptäcka mer om vad Vintergatan består av, dess historia och dess evolution.

Gaia lanserades 2014 och förmodas vara helt avslutad omkring 2022 och kommer då kunna erbjuda den största astrometriska stjärnkatalogen någonsin. Eftersom man inte förväntas få en komplett stjärnkatalog från Gaia förräns om ungefär 5 år, så kommer det lanseras mellanliggande, mindre kataloger som innehåller den information man lyckats samla in under tiden. Den första av dessa mindre katalogerna kallas för Gaia-DR1 (Gaia Data Release 1) och innehåller information för de första 14 månaderna som projektet varit aktivt. Det är denna mindre katalog som vi har använt i detta examensarbete i ett försök att uppskatta den totala prestandan som den kompletta Gaia katalogen kommer att erbjuda. Genom att redan nu undersöka möjligheterna och begränsningarna med Gaia, kan vi planera i förtid på hur de kommande projekten som använder sig av Gaia kommer kunna ge oss en större inblick i hur vårt universum fungerar. Astronomerna hoppas kunna erhålla den mest kompletta beskrivningen av vår galax någonsin genom implementationen av den information som Gaia kommer att erbjuda. (Less)
Please use this url to cite or link to this publication:
author
Prgomet, Mateo LU
supervisor
organization
course
ASTK02 20171
year
type
M2 - Bachelor Degree
subject
publication/series
Lund Observatory Examensarbeten
report number
2017-EXA126
language
English
id
8914937
date added to LUP
2017-06-22 16:11:21
date last changed
2017-06-22 16:11:21
@misc{8914937,
  abstract     = {The first part of this thesis deals with the dynamical estimation of the Oort constants using proper motions and parallaxes provided from the Gaia-DR1 TGAS catalogue. The photometric information was provided by the 2MASS catalogue. The Oort constants calculated from the TGAS catalogue are compared to those obtained from the original Hipparcos catalogue in order to attempt to estimate how well Gaia-DR1 performs. A least squares approach was implemented to calculate the Oort constants. This routine contained seven parameters where the stellar LSR velocity components were included as well. The overall trend seems to be such that the TGAS catalogue can provide meaningful and potentially better results compared to that of the Hipparcos catalogue if the study is not sensitive to a catalogue that is colour incomplete. TGAS worked fairly well in the determination of the Oort constants mainly due to its large sample size, giving it a statistical edge over the Hipparcos catalogue. 

In the second part of the thesis the local mass density, ρ₀, was determined using tracer star populations for two catalogues. The first one was the original Hipparcos catalogue where the data was propagated to the year 2015. The second catalogue was a combination of Hipparcos stars obtained from both the TGAS and the propagated HIP catalogues. This was done in order to avoid the incompleteness issue that resulted after the creation of the TGAS catalogue. 

The estimated local mass density from the propagated Hipparcos catalogue was ρ₀ = 0.112 ± 0.009 solar masses per pc³ while the combined TGAS sample got ρ₀ = 0.113 ± 0.006 solar masses per pc³. This result implies that the TGAS catalogue is slightly better compared to the HIP catalogue in performance since it provides with lower formal errors.

Based on the results of the two dynamical estimations performed, the TGAS catalogue can be seen as marginally better when compared to the HIP catalogue. In addition, the formal errors resulting from the calculations using the TGAS catalogue are better compared to those obtained using the HIP catalogue. The formal errors are especially good when dynamically estimating the Oort constants since so many stars are included in the calculations. It is, however, difficult to estimate the performance of the complete Gaia catalogue by simply considering the first data release. The release of Gaia-DR2 will hopefully resolve the questions surrounding the performance of the Gaia catalogue.},
  author       = {Prgomet, Mateo},
  language     = {eng},
  note         = {Student Paper},
  series       = {Lund Observatory Examensarbeten},
  title        = {Assessing the Improvements GAIA-DR1 Will Bring to Dynamical Astronomy},
  year         = {2017},
}