IAO 2018, Практически тур — Задача 6β. Binary system S Ant

IAO 2018 — Practical round (α and β)

Practical round. Problems to solve

XXIII International Astronomy Olympiad. Colombo, Sri Lanka, 6–14 X 2018. This source combines groups α and β. The distinct task 6 of each group is identified as 6α and 6β; tasks 7 and 8 are shared and are reproduced once.

Бележки от източника

The repeated 0.25, 0.32 and 0.37 Julian-day entries in the α table 6 are retained exactly. The α data sheet bears the header Theo although the body says Practical round. Question 8.5 refers to provided graph paper, which is absent from this source pack. Matching official practical solutions were not found in the complete same-year catalogue.

Shared reference inventory

The two separately archived data photographs are labelled Theo: data_1 contains Solar-System properties, the equation of time and Colombo coordinates; data_2 contains physical constants and formulae. They were read to check reference coverage and do not contain missing practical graph paper, additional practical tasks or official solutions.

Условие

S Ant is an eclipsing binary which was observed in spectroscopy using 45 cm Cassegrain telescope at Arthur C Clarke institute, Sri Lanka. The figure 6. shows the Hα absorption line profiles of S Ant observed in different phases (phases are indicated on the right) of the binary orbit. The two stars are very close by and the secondary component is merged with the primary so that the primary component is only visible in the spectrum. The secondary component was recovered by special image processing program method (deblending) and the radial velocities are given in the table 6. The spectra are shifted in Y axis for the clarity.

6.1 Draw a table for the first three columns as shown in table 6. Measure the wavelength shift of the Hα lines assuming Hα is 6563 Å and fill the table. Calculate radial velocity of the primary component.

6.2 Plot the radial velocities of primary and secondary components vs phase in the same sheet of graph paper.

6.3 Draw the smooth best fit radial velocity curves for primary and secondary components.

6.4 Calculate velocities of the primary ($V_p$) and secondary ($V_s$) components in km/s.

6.5 Calculate masses of the components of the system if the period $P=0.65$ days. Inclination angle of the system orbit is $i=70°$.

Table 6

Phase	$\Delta\lambda$ (Å)	Radial velocity of primary (km/s)	Radial velocity of secondary (km/s)
0.09			Not available
0.20			211
0.30			235
0.35			189
0.48			Not available
0.54			Not available
0.61			Not available
0.65			-171
0.70			-267
0.76			-224
0.81			-148
0.90			Not available
0.95			Not available

Fig. 6

Решение

Теми и трудност

Трудност: неоценена.

Звезди · Светлина и астрономически измервания · Двойни звезди · Доплерово отместване и червено отместване

Предпоставки: Разширена олимпиадна подготовка

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Оригинал в Архива: pract.pdf · допълнителни данни: data_1.jpg · допълнителни данни: data_2.jpg