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RESOLUTION B
The IAU Strategic Plan 2010-2020: Astronomy for Development
(Proposed by the Executive Committee)
The XXIX General Assembly of the International Astronomical Union,
Recognising
1. That the XXVII General Assembly, meeting in Rio de Janiero, Brazil, on
13 August 2009 unanimously passed a Resolution resolving that the IAU
should “approve the goals specified in the Strategic Plan: Astronomy for
the Development as objectives for the IAU in the coming decade,
2. That to further these objectives the IAU established the Office of
Astronomy for Development (OAD) in Cape Town, South Africa, as an
equal partnership between the IAU and the National Research Foundation
of South Africa,
3. That the OAD has successfully promoted an ambitious international
programme of activities in pursuit of the objectives of the IAU Strategic
Plan,
4. That a recent independent review of the OAD concluded that “its
performance has been outstanding, particularly given the very limited
resources that have been made available to an organisation with such
ambitious terms of reference,”
Resolves
1. That the pursuit of the goals of the Strategic Plan: Astronomy for the
Developing World should continue until the XXXI General Assembly to
be held August 2021,
2. That the Executive Committee should present for approval at the XXX
General Assembly to be held in Vienna, Austria in August 2018 an
extended Strategic Plan which addresses the future of the OAD and its
activities beyond 2021,
3. That the Executive Committee should consult existing and potential
stakeholders in the preparation of this Strategic Plan.
RESOLUTION B
on recommended zero points for the absolute
and apparent bolometric magnitude scales
Proposed by IAU Inter-Division A-G Working Group on Nominal Units for Stellar &
Planetary Astronomy
The XXIXth International Astronomical Union General Assembly,
Noting
- the absence of an exact definition of the zero point for the absolute and ap- parent bolometric magnitude scales, which has resulted in the proliferation of different zero points for bolometric magnitudes and bolometric correc- tions in the literature (ranging at approximately the tenth of a magnitude level; see e.g., Bessell, Castelli, & Plez 1998; Torres 2010),
- that IAU Commissions 25 and 36 approved identical draft resolutions for
defining the zero point for the bolometric magnitude scale (Andersen 1999), but that the resolution never subsequently reached the stage of approval by the IAU General Assembly, and was only sporadically adopted within the astronomical community,
- that recent total solar irradiance measurements have led to a revised solar luminosity that differs slightly from the value used to set the zero point of the absolute bolometric magnitude scale in the Commission 25 and 36 draft resolutions,
and hence the apparent bolometric magnitude mBol for an irradiance f (in W m−^2 ) is
mBol = − 2 .5 log ( f / f◦) = − 2 .5 log f − 18 .997 351 ... (4)
The irradiance f◦ corresponds to that measured from an isotropically emit- ting radiation source with absolute bolometric magnitude MBol = 0 mag (luminosity L◦) at the standard distance^4 of 10 parsecs (based on the IAU 2012 definition of the astronomical unit).
The adopted value of f◦ agrees with some in common use (e.g., Lang 1974, Cox 2000) at the level of < 0. 1 %. Using this zero point, the nominal total solar irradiance S N^ (1361 W m−^2 ) corresponds to a solar apparent
bolometric magnitude of mBol ' − 26. 832 mag.
References
Andersen, J. 1999, Transactions of the International Astronomical Union, Series B, 23, pgs. 141 & 182
Bessell, M. S., Castelli, F., & Plez, B. 1998, Astronomy & Astrophysics, 333, 231
Binney, J., & Tremaine, S. 2008, Galactic Dynamics: Second Edition, ISBN 978-0-691-13026-2 (HB). Published by Princeton University Press, Princeton, NJ USA
Bureau International des Poids et Mesures, 2006, The International System of Units (SI), 8th edition, Organisation Intergouvernementale de la Convention du M´etre
Cox, A. N. 2000, Allen’s Astrophysical Quantities, 4th Edition
Kopp, G. 2014, Journal of Space Weather and Space Climate, 4, A
Kopp, G., Lawrence, G., Rottman, G., 2005, Solar Physics, 230, 129
Kopp, G., & Lean, J. L. 2011, Geophysical Research Letters, 38, L
Lang, K. R. 1974, Astrophysical Formulae, A Compendium for the Physicist and Astrophysicist, Springer-Verlag
Meftah, M., Irbah, A., Hauchecorne, A., et al. 2015, Solar Physics, 290, 673
Schmutz W., Fehlmann A., Finsterle W., et al. 2013, AIP Conf. Proc. 1531, p. 624627, doi:10.1063/1.
Torres, G. 2010, Astronomical Journal, 140, 1158
Wilkins, G. A. 1989, “The IAU Style Manual (1989): The Preparation of Astro- nomical Papers and Reports”
Willson, R. C. 2014, Astrophysics & Space Science, 352, 341
Notes
(^1) The notation of Mbol referring to absolute bolometric magnitude and mbol referring to appar- ent bolometric magnitude was adopted by Commission 3 (Notations) at the VIth IAU General As- sembly in Stockholm in 1938: https://www.iau.org/static/resolutions/IAU1938 French.pdf. MBol and mBol refer specifically to bolometric magnitudes defined using the zero points of this resolu- tion. (^2) Modern spaceborne total solar irradiance (TSI) instruments are absolutely calibrated at the
0.03% level (Kopp 2014). The TIM/SORCE experiment established a lower TSI value than pre- viously reported based on the fully characterized TIM instrument (Kopp et al. 2005, Kopp & Lean 2011). This revised TSI scale was later confirmed by PREMOS/PICARD, the first space- borne TSI radiometer that was irradiance-calibrated in vacuum at the TSI Radiometer Facil- ity (TRF) with SI-traceability prior to launch (Schmutz et al. 2013). The DIARAD/PREMOS (Meftah et al. 2015), ACRIM3/ACRIMSat (Willson 2014), VIRGO/SoHO, and TCTE/STP-Sat (http://lasp.colorado.edu/home/tcte/) flight instruments are now consistent with this new TSI scale within instrument uncertainties, with the DIARAD, ACRIM3, and VIRGO having made post- launch corrections and the TCTE having been validated on the TRF prior to its 2013 launch. The cycle 23 observations with these experiments are consistent with a TSI value (rounded to an appro- priate number of significant digits) and uncertainty of: S = 1361 (± 1) W m−^2 (2σ uncertainty). The uncertainty range includes contributions from the absolute accuracies of the latest TSI instru- ments as well as uncertainties in assessing a secular trend in TSI over solar cycle 23 using older measurements. Combining this total solar irradiance value with the IAU 2012 definition of the as- tronomical unit leads to a current best estimate of the mean solar luminosity of L = 4 π (1 au)^2 S = 3.8275 (± 0.0014) × 1026 W. Based on this, a nominal solar luminosity of LN^ = 3.828 × 1026 W is adopted. Using the proposed zero point L◦, the nominal solar luminosity LN^ corresponds to bolometric magnitude MBol ' 4.739 996 ... mag — i.e., sufficiently close to 4.74 mag for any foreseeable practical purpose. (^3) The terms irradiance and heat flux density are used interchangeably, both with SI
units of W m−^2 (Wilkins 1989, Bureau International des Poids et Mesures 2006). See also https://www.iau.org/publications/proceedings rules/units/. (^4) The parsec is defined as exactly (648 000/π) au (e.g. Cox 2000, Binney & Tremaine 2008).
Using the IAU 2012 Resolution B2 definition of the astronomical unit, the parsec corresponds to 3.085 677 581 ... × 1016 m. As the absolute bolometric magnitude zero point and astronomical unit are defined exactly, further digits for the apparent bolometric magnitude zero point irradiance f◦ may be calculated if needed.
rapidly increasing accuracy of spectroscopic, photometric, and interfero- metric observations of stars and extrasolar planets^1 , and
- that the universal constant of gravitation G is currently one of the least pre- cisely determined constants, whereas the error in the product GM is five orders of magnitude smaller (Petit & Luzum 2010, and references therein),
Recommends
In all scientific publications in which accurate values of basic stellar or planetary properties are derived or quoted:
- that whenever expressing stellar properties in units of the solar radius, total solar irradiance, solar luminosity, solar effective temperature, or solar mass parameter, that the nominal values RN^ , SN^ , LN^ , T (^) eNff , and (GM)N^ , be used, respectively, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only — chosen to be close to the current best estimates (see table below) — not as the true solar properties. Their consistent use in all relevant formulas and/or model calculations will guarantee a uniform conversion to SI units. Symbols such as L and R , for example, should only be used to refer to actual estimates of the solar luminosity and solar radius (with uncertainties),
- that the same be done for expressing planetary properties in units of the equatorial and polar radii of the Earth and Jupiter (i.e., adopting nominal values RN eE, RN pE, R eNJ, and RN pJ, expressed in meters), and the nominal ter- restrial and jovian mass parameters (GM)NE and (GM)NJ , respectively (ex- pressed in units of m^3 s−^2 ). Symbols such as GME, listed in the IAU 2009 system of astronomical constants (Luzum et al. 2011), should only be used to refer to actual estimates (with uncertainties),
- that the IAU (2015) System of Nominal Solar and Planetary Conversion Constants be adopted as listed below:
SOLAR CONVERSION CONSTANTS 1 RN^ = 6. 957 × 108 m 1 SN^ = 1361 W m−^2 1 LN^ = 3. 828 × 1026 W 1 T (^) eNff = 5772 K 1(GM)N^ = 1 .327 124 4 × 1020 m^3 s−^2
PLANETARY CONVERSION CONSTANTS
1 RN eE = 6. 3781 × 106 m 1 RN pE = 6. 3568 × 106 m 1 RN eJ = 7. 1492 × 107 m 1 RN pJ = 6. 6854 × 107 m 1 (GM)NE = 3 .986 004 × 1014 m^3 s−^2 1 (GM)NJ = 1 .266 865 3 × 1017 m^3 s−^2
- that an object’s mass can be quoted in nominal solar masses MN^ by taking the ratio (GM)object/(GM)N^ , or in corresponding nominal jovian and terres- trial masses, MNJ and MNE , respectively, dividing by (GM)NJ and (GM)NE. If SI masses are explicitly needed, they should be expressed in terms of (GM)object/G, where the estimate of the Newtonian constant G should be ex- plicitly specified in the publication (for example, the 2014 CODATA value is G = 6 .67408 (± 0 .00031) × 10 −^11 m^3 kg−^1 s−^2 ).
- that if nominal volumes are needed, that a nominal terrestrial volume be derived as 4 π RN eE^2 RN pE/ 3 , and nominal jovian volume as 4 π RN eJ^2 RN pJ/ 3.
Explanation
- The need for increased accuracy has led to a requirement to distinguish between Barycentric Coordinate Time (TCB) and Barycentric Dynamical Time (TDB). For this reason the nominal solar mass parameter (GM)N value is adopted as an exact number, given with a precision within which its TCB and TDB values agree (Luzum et al. 2011). This precision is considered to be sufficient for most applications in stellar and exoplanetary research for the forseeable future.
- The nominal solar radius RN^ corresponds to the solar photospheric radius measured by Haberreiter et al. (2008)^2 , who resolved the long-standing dis- crepancy between the seismic and photospheric solar radii. This RN^ value is consistent with that adopted by Torres et al. (2010) in their recent compi- lation of updated radii of well observed eclipsing binary systems.
- The nominal total solar irradiance SN^ corresponds to the mean total elec- tromagnetic energy from the Sun, integrated over all wavelengths, incident
(Luzum et al. 2011), subtracting off the contribution from the Galilean satel- lites (Jacobson et al. 2000). The quoted value is rounded to the precision within which the TCB and TDB values agree, and the uncertainties in the masses of the satellites are negligible.
- The nominal value of a quantity Q can be transcribed in LaTeX with the help of the definitions listed below for use in the text and in equations:
\newcommand{\Qnom}{\hbox{$\mathcal{Q}ˆ{\rm N}{\odot}$}} \newcommand{\Qn}{\mathcal Qˆ{\rm N}{\odot}}
References
Archinal, B. A., A’Hearn, M. F., Bowell, E., et al. 2011, Celestial Mechanics and Dynamical Astronomy 109, 101
Haberreiter, M., Schmutz, W., Kosovichev, A. G. 2008, ApJ, 675, L
Harmanec, P., Prˇsa, A. 2011, PASP, 123, 976
Jacobson, R. A., Haw, R. J., McElrath, T. P., & Antreasian, P. G. 2000, J. Astro- naut. Sci. 48(4), 495
Kopp, G. 2014, Journal of Space Weather and Space Climate, 4, A
Kopp, G., Lawrence, G., Rottman, G., 2005, Solar Physics, 230, 129
Kopp, G., & Lean, J. L. 2011, Geophys. Res. Letters, 38, L
Luzum, B., Capitaine, N., Fienga, A., et al. 2011, Celestial Mechanics and Dy- namical Astronomy, 110, 293
McCarthy, D. D. & Petit, G. 2004 IERS Technical Note No. 32, 1
Meftah, M., Irbah, A., Hauchecorne, A., et al. 2015, Solar Physics, 290, 673
Petit, G., Luzum, B. (Eds.) 2010 IERS Technical Note No. 36
Pouillet, C. S. M. 1838, Memoire sur le chaleur solaire, Paris, Bachelier
Prˇsa, A. & Harmanec, P. 2012, Proc. IAU Symp. 282, Cambridge Univ., Press, 339
Schmutz W., Fehlmann A., Finsterle W., et al. 2013, AIP Conf. Proc. 1531, p. 624627, doi:10.1063/1.
Torres, G., Andersen, J., Gim´enez, A. 2010, A&A Rev., 18, 67
Willson, R. C. 2014, Astrophysics & Space Science, 352, 341
Willson, R. C. 1978, Journal of Geophysical Research, 83, 4003
Notes
(^1) Note, e.g., that since projected rotational velocities of stars (v sin i) are measured in SI units,
the use of different values for the solar radius can lead to measurable differences in the rotational periods of giant stars (see Harmanec and Prˇsa 2011). (^2) Haberreiter et al. (2008) measured the solar photospheric radius to be 695 658 (± 140) km.
The adopted RN^ is based on this value, quoting an appropriate number of significant figures given the uncertainty, and differs slightly from the nominal solar radius tentatively proposed by Har- manec & Prˇsa (2011) and Prˇsa & Harmanec (2012). (^3) The TSI is variable at the ∼0.08% (∼1 W m− (^2) ) level and may be variable at slightly larger
amplitudes over timescales of centuries. Modern spaceborne TSI instruments are absolutely cal- ibrated at the 0.03% level (Kopp 2014). The TIM/SORCE experiment established a lower TSI value than previously reported based on the fully characterized TIM instrument (Kopp et al. 2005, Kopp & Lean 2011). This revised TSI scale was later confirmed by PREMOS/PICARD, the first spaceborne TSI radiometer that was irradiance-calibrated in vacuum at the TSI Radiometer Fa- cility (TRF) with SI-traceability prior to launch (Schmutz et al. 2013). The DIARAD/PREMOS (Meftah et al. 2015), ACRIM3/ACRIMSat (Willson 2014), VIRGO/SoHO, and TCTE/STP-Sat (http://lasp.colorado.edu/home/tcte/) flight instruments are now consistent with this new TSI scale within instrument uncertainties, with the DIARAD, ACRIM3, and VIRGO having made post- launch corrections and the TCTE having been validated on the TRF prior to its 2013 launch. The Cycle 23 observations with these experiments are consistent with a mean TSI value of S = 1361 W m−^2 (± 1 W m−^2 ; 2σ). The uncertainty range includes contributions from the ab- solute accuracies of the latest TSI instruments as well as uncertainties in assessing a secular trend in TSI over solar cycle 23 using older measurements. (^4) Resolution B2 of the XXVIII General Assembly of the IAU in 2012 defined the astronomical
unit to be a conventional unit of length equal to 149 597 870 700 m exactly. Using the current best estimate of the TSI (discussed in endnote 3), this is consistent with a current best estimate of the Sun’s mean radiative luminosity of L = 4 π (1 au)^2 S = 3.8275 (± 0.0014) × 1026 W. (^5) The CODATA 2014 value for the Stefan-Boltzmann constant is σ = 5 .670 367 (± 0 .000 013)×
10 −^8 W m−^2 K−^4. The current best estimate for the solar effective temperature is calculated to be Teff, = 5772.0 (± 0.8) K.
- that radio frequencies are a limited resource that should be shared,
- that automobile manufacturers intend to utilize millimeter-wave radars operating in the frequency range 76 - 81 GHz for a number of purposes, that include the increasing of safety in driving,
- that agenda item 1.18 of World Radiocommunication Conference 2015 (WRC-15) of the ITU calls for consideration of allocating the frequency range 77.5 – 78 GHz to radar applications worldwide, and that this allocation is expected to be applied worldwide in conjunction with existing allocations to radar applications in the frequency range 76 – 81 GHz,
- that the ITU has not identified measures to protect radio astronomy observations in the frequency range 76– 81 GHz from interference caused by automobile radars.
Resolves
- to request that WRC-15 take all possible steps to protect radio astronomy observations in the range 76 – 81 GHz from interference caused by automobile radars,
- to express the view that the most effective protection of radio astronomy observations would be through geographical separation,
- to send a copy of this resolution to administrations that operate or host radio astronomy observations in the frequency range 76 – 81 GHz, and where automobile radars are operating or plan to operate in the same frequency range,
- to encourage astronomers, particularly those in countries that fall under Resolves 3, to work proactively in protecting radio astronomy observations in the frequency range 76 – 81 GHz.
