Conversion entre Hp (magnitud de Hipparcos) y V
La conversión depende del color de la estrella. Las diferentes columnas de esta tabla muestran esta relación en función de B-V y del tipo espectral. La primer columna contempla la mayoría de los casos e incluye todas las estrellas hasta A9, todas las estrellas, salvo las de secuencia principal, hasta G0, y las gigantes y subgigantes entre G1 y K9. A partir de la clase F las enanas (clases V y IV-V) presentan una leve diferenciación contemplada en la segunda columna. Para gigantes brillantes y supergigantes (clases I y II) de tipo espectral G y K la tercer columna debe ser usada. No hay forma de establecer una relación coherente para estrellas de tipo espectral M ó peculiares, ya que la presencia de diferentes moléculas en la atmósfera estelar influye decisivamente en un filtro de banda tan ancha como el de Hipparcos. Nótese que la conversión para índices de color tan altos como 1.9, no deberá corresponder nunca a estrellas tipo M sino a estrellas fuertemente enrojecidas por el medio interestelar. Aquí puede comprobarse que puede hacerse una conversión lineal basada en el color, pero siempre y cuando la atmósfera no presente complicaciones químicas que enturbien la tarea del detector. La calibración está basada en chequeos continuos realizados por Otero entre magniutdes Hp y V en el marco de la preparación de nuevas y precisas secuencias fotoeléctricas para
la revisión de cartas de LIADA. La diferencia fundamental que da cuenta de las discrepancias con Bessell (2000) para estrellas con B-V mayor a 1.5 es la exclusión de este estudio de las estrellas tipo M (inclusive las gigantes).
Relation between Hp and V magnitudes
The relation between the systems can be understood in terms of the color of the star.
This table shows this relation as a function of B-V and spectral type of the star.
The first column includes all of the stars up to A9 spectral type, and all the stars up to G0 -excepting those of the main sequence- and giants and subgiants between G1 and K9.
Starting at class F, dwarves (classes V and IV-V) show a slight difference that is reflected in the second column.
For bright giants and supergiants (classes I and II) of spectral type G and K, the third column must be used.
There's no way to establish a linear relation for stars of spectral type M or peculiar stars, since the presence of
different molecules in the stellar atmosphere strongly influences the magnitude as measured by a filter with a broad band as the Hipparcos one.
Note that when converting from B-V indexes as high as e.g. 1.9, we shouldn't include M stars but only stars strongly reddened by interstellar absorption.
This proves that a linear conversion can be done using the B-V color index but as long as the star's atmosphere doesn't show chemical peculiarities that can "fool" the detector.
Calibration is based in continuous comparison between Hp and V magnitudes performed by Otero while creating new photometric sequences and charts for bright variables.
The main difference between this table and that presented by Bessell (2000) is the exclusion of all of the M stars from the relation.
O3-A9I/V - F0-G0I/IV F0-K9V G1-K9I-II G1-K9III/IV
B-V V-Hp
-0.30 0.125 -0.29 0.120 -0.28 0.115 -0.27 0.108 -0.26 0.100 -0.25 0.094 -0.24 0.090 -0.23 0.087 -0.22 0.084 -0.21 0.079 -0.20 0.073 -0.19 0.067 -0.18 0.063 -0.17 0.059 -0.16 0.056 -0.15 0.051 -0.14 0.047 -0.13 0.043 -0.12 0.038 -0.11 0.033 -0.10 0.030 -0.09 0.026 -0.08 0.023 -0.07 0.019 -0.06 0.015 -0.05 0.010 -0.04 0.005 -0.03 0.002 -0.02 -0.001 -0.01 -0.005 0.00 -0.009 0.01 -0.012 0.02 -0.015 0.03 -0.018 0.04 -0.021 0.05 -0.024
0.06 -0.027
0.07 -0.031 0.08 -0.034 0.09 -0.037 0.10 -0.040 0.11 -0.043 0.12 -0.046 0.13 -0.048 0.14 -0.050 0.15 -0.052 0.16 -0.054 0.17 -0.057 0.18 -0.059 0.19 -0.061 0.20 -0.062 0.21 -0.064 0.22 -0.066 0.23 -0.067 0.24 -0.069 0.25 -0.070 0.26 -0.071 0.27 -0.072 0.28 -0.073 0.29 -0.074 0.30 -0.076 -0.075 0.31 -0.078 -0.076 0.32 -0.079 -0.077 0.33 -0.081 -0.078 0.34 -0.082 -0.079 0.35 -0.084 -0.080 0.36 -0.086 -0.081 0.37 -0.087 -0.082 0.38 -0.089 -0.083 0.39 -0.091 -0.084 0.40 -0.092 -0.086 0.41 -0.093 -0.088 0.42 -0.095 -0.090 0.43 -0.096 -0.092 0.44 -0.098 -0.094 0.45 -0.100 -0.096 0.46 -0.102 -0.097 0.47 -0.103 -0.098 0.48 -0.105 -0.100 0.49 -0.107 -0.103 0.50 -0.109 -0.105 0.51 -0.111 -0.107 0.52 -0.113 -0.109 0.53 -0.115 -0.110 0.54 -0.117 -0.112 0.55 -0.120 -0.114 0.56 -0.122 -0.116 0.57 -0.124 -0.117 0.58 -0.125 -0.118 0.59 -0.126 -0.120 0.60 -0.127 -0.122 0.61 -0.128 -0.123 0.62 -0.129 -0.124 0.63 -0.130 -0.125 0.64 -0.131 -0.126 0.65 -0.132 -0.128 0.66 -0.133 -0.129 0.67 -0.134 -0.130 0.68 -0.136 -0.131 0.69 -0.137 -0.132 0.70 -0.138 -0.134 0.71 -0.139 -0.135 0.72 -0.140 -0.136 0.73 -0.141 -0.137 0.74 -0.142 -0.138 0.75 -0.143 -0.139 0.76 -0.144 -0.140 0.77 -0.145 -0.141 0.78 -0.147 -0.142 0.79 -0.148 -0.142 0.80 -0.149 -0.143 0.81 -0.150 -0.143 0.82 -0.151 -0.144 0.83 -0.152 -0.144 0.84 -0.153 -0.145 0.85 -0.154 -0.145 0.86 -0.155 -0.146 0.87 -0.156 -0.147 0.88 -0.156 -0.147 0.89 -0.157 -0.148 0.90 -0.157 -0.149 0.91 -0.158 -0.149 0.92 -0.159 -0.150 0.93 -0.159 -0.151 0.94 -0.160 -0.151 0.95 -0.160 -0.152 0.96 -0.161 -0.153 0.97 -0.161 -0.153 0.98 -0.162 -0.154 0.99 -0.163 -0.154 1.00 -0.163 -0.155 1.01 -0.164 -0.155 1.02 -0.165 -0.156 1.03 -0.165 -0.156 1.04 -0.166 -0.157 1.05 -0.166 -0.157 -0.167 1.06 -0.167 -0.158 -0.168 1.07 -0.168 -0.158 -0.169 1.08 -0.168 -0.158 -0.170 1.09 -0.169 -0.158 -0.171 1.10 -0.169 -0.159 -0.172 1.11 -0.169 -0.159 -0.174 1.12 -0.170 -0.159 -0.175 1.13 -0.170 -0.160 -0.177 1.14 -0.171 -0.160 -0.179 1.15 -0.171 -0.160 -0.180 1.16 -0.171 -0.160 -0.180
1.17 -0.170 -0.160 -0.180 1.18 -0.170 -0.159 -0.179 1.19 -0.170 -0.159 -0.179 1.20 -0.169 -0.159 -0.178 1.21 -0.169 -0.159 -0.178 1.22 -0.168 -0.158 -0.176 1.23 -0.168 -0.158 -0.175 1.24 -0.167 -0.158 -0.173 1.25 -0.166 -0.157 -0.172 1.26 -0.165 -0.157 -0.171 1.27 -0.164 -0.156 -0.170 1.28 -0.162 -0.156 -0.169 1.29 -0.160 -0.155 -0.168 1.30 -0.159 -0.155 -0.167 1.31 -0.157 -0.154 -0.166 1.32 -0.155 -0.153 -0.165 1.33 -0.153 -0.151 -0.164 1.34 -0.151 -0.163 1.35 -0.149 -0.163 1.36 -0.148 -0.162 1.37 -0.147 -0.162 1.38 -0.146 -0.161 1.39 -0.145 -0.161 1.40 -0.144 -0.160 1.41 -0.143 -0.159 1.42 -0.142 -0.159 1.43 -0.141 -0.158 1.44 -0.140 -0.157 1.45 -0.138 -0.156 1.46 -0.135 -0.155 1.47 -0.133 -0.154 1.48 -0.131 -0.153 1.49 -0.129 -0.152 1.50 -0.127 -0.151 1.51 -0.125 -0.150 1.52 -0.123 -0.149 1.53 -0.121 -0.148 1.54 -0.120 -0.147 1.55 -0.119 -0.145 1.56 -0.118 -0.144 1.57 -0.117 -0.143 1.58 -0.116 -0.141 1.59 -0.115 -0.140 1.60 -0.114 -0.139 1.61 -0.113 -0.138 1.62 -0.112 -0.137 1.63 -0.111 -0.136 1.64 -0.110 -0.135 1.65 -0.109 -0.134 1.66 -0.108 -0.133 1.67 -0.107 -0.132 1.68 -0.106 -0.131 1.69 -0.105 -0.130 1.70 -0.104 -0.129 1.71 -0.103 1.72 -0.102 1.73 -0.101 1.74 -0.100 1.75 -0.099 1.76 -0.098 1.77 -0.098 1.78 -0.097 1.79 -0.097 1.80 -0.096 1.81 -0.095 1.82 -0.094 1.83 -0.093 1.84 -0.092 1.85 -0.091 1.86 -0.090 1.87 -0.089 1.88 -0.088 1.89 -0.087 1.90 -0.086 1.91 -0.086 1.92 -0.085 1.93 -0.084 1.94 -0.083 1.95 -0.082 1.96 -0.081 1.97 -0.080 1.98 -0.079 1.99 -0.078 2.00 -0.077
* Bessell, M., 2000, PASP, 112, 961-965, The Hipparcos and Tycho Photometric System Passbands.
* Perryman, M.A.C., et al., 1997, The Hipparcos and Tycho Catalogues, ESA SP-1200
Otero, 2001.
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