[vsnet-newvar 1714] Re: [vsnet-campaign-unknown 134] Re: MisV1147 Spectral Type

[DWest61506@aol.com]

In a message dated 12/5/2002 7:58:24 PM Central Standard Time, tkato@kusastro.kyoto-u.ac.jp writes:

Re: [vsnet-campaign-unknown 133] MisV1147 Spectral Type

> B-V implies K0 spectral type
> U-B implies A5 or G0 spectral type
>
> From M.S. Bessell, PASP, 91:589-607, October 1979
>
> V-Ic=1.186 implies K4V or K2III
>
> These colors are not consistent with a single star which leads credence to
> the possibility previously discussed that this is a binary system.

   Please don't neglect interstellar reddening.

Regards,
Taichi Kato

MisV1147 Spectral Type

In response to Dr. Kato request to de-redden my MisV1147 spectral class calculation I submit the following analysis.

The simplest approach to calculate the de-redden spectral class is to use the Q parameter defined in Henden and Kaithcuck.  Q is defined as: Q = (U-B)obs - 0.72*(B-V)obs.

Henden photometry:
No. HJD      V        B-V   U-B   V-R   R-I
1 52288.61 13.365 0.814 0.087 0.558 0.628
2 52577.67 14.876 0.933 0.044 0.706 0.906

For observation number 1
Q = (U-B)obs -  0.72*(B-V)obs = 0.087 - 0.72*(0.814) = -0.5
Which equates to spectral type B4.5

For observation number 2
Q = (U-B)obs -  0.72*(B-V)obs = 0.044 - 0.72*(0.933) = -0.63
Which equates to spectral type B2.5

This implies the object gets bluer as during fading episodes, which isn't consistent with the changes in V-R and R-I.  I am still working on the spectral class based on R and I colors.

Regards,
Doug West


Reference
A. Henden and R. Kaitchuck, Astronomical Photometry, Van Nostrand Reinhold Co., 1982.

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