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Asteroseismology: Looking inside stars
Rømer
Jørgen Christensen-Dalsgaard & Hans Kjeldsen
Aarhus Universitet
Asteroseismology:
Looking inside stars
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10
Mission Objective and Critical mission requirements
Rømer Payload: MONS
Telescope Design
Orbit
Platform Design
Rømer (1999-200?)
Mission Objective and Critical mission requirements
Rømer primary mission objective
To provide new insights into the structure and
evolution of stars, using them as laboratories to
understand physics under extreme conditions, by
studying oscillations in a sample of 20 solar-type
stars.
Mission Objective and Critical mission requirements
Rømer secondary mission objectives
1. To study the structure and evolution of stars hotter
and more massive than the Sun (delta Scuti and
rapidly oscillating Ap stars) by measuring their
oscillations.
2. To study variability in a large sample of stars
of all types.
Mission Objective and Critical mission requirements
Scientific aims (Rømer):
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Properties of convective cores, including overshoot
Structure and age of low-metallicity stars
Physical properties of stellar matter
Stellar helium abundances
Effects and evolution of stellar internal rotation
Dependence of the excitation of oscillations
Surface features
Convective motions on stellar surfaces
Reflected lights from exoplanets (and transits)
Mission Objective and Critical mission requirements
Rømer Payload Objectives
• Photometric precision: We must be able to detect
oscillations that have very low amplitudes (1-10 ppm)
• Temporal coverage: Each primary target must be
observed almost continuously for at least one month,
ideally substantially longer
• Sky coverage: The science goals require access
to the whole sky over the course of the mission
Colour oscillation signal
Solar data from VIRGO on SOHO
Key mission parameters
Mission parameter
Size
Primary payload
Secundary instruments
Weight
Description
60 x 60 x 71 cm
MONS optical telescope and Field Monitor
2 star imagers
99 kg
Power consumption
55 Watt, average
Downlink datarates
Max. 24 Mbyte/day
Orbit
Launch
Highly elliptical (Molniya)
Apogee: 40.000 km - Perigee: 600 km
Inclination: 63.4
SOYUZ/FREGAT
32 cm telescope
15
Image on CCD
Molniya orbit: Rømer
Orbit is a 400 x 40,000km
63.4° inclination
a = 26600 km
e=0.75
i = 63.4
P=11.967 hrs.
Change in right ascension of the
ascending node:
-0.030 deg/day
Change in argument of perigee:
0.000 deg/day
ADCS:
Attitude Determination
and Control Subsystem
Communication
CDH:
Command and Data
Handling Subsystem
Thermal
Power
Structure and
Mechanisms
ADCS:
Attitude Determination
and Control Subsystem
Communication
CDH:
Command and Data
Handling Subsystem
Thermal
Power
Structure and
Mechanisms
20
ADCS:
Attitude Determination
and Control Subsystem
Communication
CDH:
Command and Data
Handling Subsystem
Thermal
Power
Structure and
Mechanisms
ADCS:
Attitude Determination
and Control Subsystem
Communication
CDH:
Command and Data
Handling Subsystem
Thermal
Power
Structure and
Mechanisms
ADCS:
Attitude Determination
and Control Subsystem
Communication
CDH:
Command and Data
Handling Subsystem
Thermal
Power
Structure and
Mechanisms
ADCS:
Attitude Determination
and Control Subsystem
Communication
CDH:
Command and Data
Handling Subsystem
Thermal
Power
Structure and
Mechanisms
ADCS:
Attitude Determination
And Control Subsystem
CDH:
Command and
Data Handling
Subsystem
Communication
Structure and
Mechanisms
Thermal
Power
ADCS:
Attitude Determination
And Control Subsystem
CDH:
Command and
Data Handling
Subsystem
Communication
Structure and
Mechanisms
Thermal
Power
ADCS:
Attitude Determination
And Control Subsystem
Communication
CDH:
Command and Data
Handling Subsystem
Structure and
Mechanisms
Thermal
Power
ADCS:
Attitude Determination
And Control Subsystem
CDH:
Command and
Data Handling
Subsystem
Communication
Structure and
Mechanisms
Thermal
Power
ADCS:
Attitude Determination
And Control Subsystem
CDH:
Command and
Data Handling
Subsystem
Communication
Structure and
Mechanisms
Thermal
Power
Ground-based support
observations
Preparatory observations
•Characterization of targets (effective temperature,
luminosity, composition)
•Charcterization of target field, including possible
interfering objects
Parallel observations
•For some objects, simultaneous ground-based velocity
observations, for characterization of strongest modes.