The Hipparcos Space Astrometry Mission: Educational Resources--light curves for unsolved variables

Hipparcos: Light Curves for Unsolved Variables

Introduction

The light curves on this page are taken from Volume 12: Part C of The Hipparcos and Tycho Catalogues. This contains light curves extending over the entire Hipparcos mission duration for non-periodic variable stars. Although no period has yet been found for these objects, it is expected that - in many cases - by following up their observations from the ground, their variability type, and perhaps their periods, may be established. This is most obvious in the case of eclipsing binary systems, where a dramatic dip in the intensity of the star indicates the occultation of one star by another in a binary system. Now that these systems have been identified as eclipsing, they can be monitored with greater intensity in anticpation of detecting a future minimum. Once this is done, the period can be determined, and future minima predicted.

Click on the HIP number of the star to return the Hipparcos Catalogue entry and further links for the star. Although none of these objects has a period determined from the Hipparcos observations, some of them are periodic. Click on the light curve icon at the bottom right of the details of each system to start an interactive search for the period of the given star. Can you supply additional observations that will help clarify the nature of these fascinating stars?

If you make new observations, you could add your new data into the existing epoch photometry file, and experiment with new period fits using the Hipparcos data in combination with your own data. The Hipparcos data used in the analysis is available by clicking on the table icon after each figure. (Data for all 11800 Hipparcos stars is available on Disk 2 of Volume 17, as file hip_ep.dat.) The data format used corresponds to that of the Epoch Photometry Annex contained in the published Hipparcos Catalogue and described in Section 2.5 of Volume 1 of the catalogues. The individual epoch photometry transit records (Fields HT1-4) are preceded by a header record (Fields HH1-4). For each transit the observation epoch is given as Field HT1 in the table. The calibrated Hipparcos magnitude and estimated standard error are given in Fields HT2 and HT3 respectively.

Example Curves from Part C (All magnitudes in the text and plots refer to the Hipparcos Hp magnitude scale) (Different plot symbols are described in Volume 1) (Further details of each object are contained in the Variability Annexes)

HIP 1146 (CR Tuc). Newly discovered as variable by Hipparcos.

HIP 3454 (V355 And). Newly discovered as variable by Hipparcos. The star is an eclipsing binary, but with only one minimum observed its period is unknown. An excellent candidate for follow-up observations to determine its period.

HIP 7755 (V770 Cas). Newly discovered as variable by Hipparcos.

HIP 11035 (AF Ari). Newly discovered as variable by Hipparcos. The star is an eclipsing binary, but with only one (or possibly two) minima observed its period is unknown. An excellent candidate for follow-up observations to determine its period.

HIP 16826 (psi Per). Already known as a variable star, it is classified as a Gamma Cassiopeiae type variable.

HIP 25302 (V1086 Ori). Already known as a variable star, it is classified as a Gamma Cassiopeiae type variable.

HIP 25655 (V1372 Ori). Newly discovered as variable by Hipparcos, it is classified as a slow irregular pulsating variable.

HIP 30878 (V455 Aur). Newly discovered as variable by Hipparcos. The star is an eclipsing binary, but with only one (or possibly two) minima observed its period is unknown. An excellent candidate for follow-up observations to determine its period.

HIP 49611 (CM Vel). Already known as a variable star, it is classified as a semi-regular pulsating variable.

HIP 52370 (V518 Car). Newly discovered as variable by Hipparcos, it is classified as a Gamma Cassiopeiae type variable.

	HIP 1146 (CR Tuc). Newly discovered as variable by Hipparcos.
HIP 3454 (V355 And). Newly discovered as variable by Hipparcos. The star is an eclipsing binary, but with only one minimum observed its period is unknown. An excellent candidate for follow-up observations to determine its period.
	HIP 7755 (V770 Cas). Newly discovered as variable by Hipparcos.
HIP 11035 (AF Ari). Newly discovered as variable by Hipparcos. The star is an eclipsing binary, but with only one (or possibly two) minima observed its period is unknown. An excellent candidate for follow-up observations to determine its period.
	HIP 16826 (psi Per). Already known as a variable star, it is classified as a Gamma Cassiopeiae type variable.
HIP 25302 (V1086 Ori). Already known as a variable star, it is classified as a Gamma Cassiopeiae type variable.
	HIP 25655 (V1372 Ori). Newly discovered as variable by Hipparcos, it is classified as a slow irregular pulsating variable.
HIP 30878 (V455 Aur). Newly discovered as variable by Hipparcos. The star is an eclipsing binary, but with only one (or possibly two) minima observed its period is unknown. An excellent candidate for follow-up observations to determine its period.
	HIP 49611 (CM Vel). Already known as a variable star, it is classified as a semi-regular pulsating variable.
HIP 52370 (V518 Car). Newly discovered as variable by Hipparcos, it is classified as a Gamma Cassiopeiae type variable.