Alternative Pre- Observation Catalogue for Photometric Follow- Up of Transiting Exoplanets

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1 Alternative Pre- Observation Catalogue for Photometric Follow- Up of Transiting Exoplanets Terreka S Hart Tennessee State University Advisor: Dr John A Johnson University of Hawai i - Institute for Astronomy Draft version 2008 August 6 ABSTRACT Extrasolar planets or exoplanets are planets that are found outside of our solar system As of July 3, 2008 there have been 307 of them detected and confirmed These planets typically orbit main sequence stars of spectral types F, G, and K They are generally in close orbit to their sun, so they are frequently Hot Jupiter sized or larger planets Due, to their large masses these exoplanets are easier to detect than those of the mass and size of Earth The discoveries of these planets ignite questions about how well we can know and understand the properties of them and their likelihood to support life Due to the fact, that most extrasolar planets are discovered indirectly, only some physical and orbital parameters are determined Theore, it is important to do follow- up research on the known exoplanets and continue searching for new ones There are approximately nine detection methods in use for detecting these planets The detection technique discussed in this paper is the Transit method This paper lects an alternative extrasolar planets catalogue intended to provide time efficient and concise preobservation information for the photometric follow- up of transiting exoplanets through OPTIC and the Nickel telescope 1 INTRODUCTION 11 TRANSIT METHOD The transit method is the detection of extrasolar planets through the observation of an extrasolar planet passing (transit) in front of its sun as seen by the observer from Earth During the transit the extrasolar planet blocks on average between 001% and 1% of its host star s visual brightness The transit method uses the decrease in the host stars light to produce brightness versus time light curves These light curves allow calculations of the planet s radius, orbital period,

2 -2- inclination, the ingress (entrance of planet into transit), the mid-transit time, the egress (the exit of the planet from transit), the total duration, and the star s radius Torres et al (2008)Observing transits also provides the possibility of measuring planetary brightness temperature, the stellar spin-orbit alignment, the planetary day-night temperature difference, absorption lines of planetary atmospheric constituents, etc Torres et al (2008) Our intended purpose for during follow- up on extrasolar planets, through the transit method, has been to obtain redefined measurements of the planet s radius and average density We observed exoplanets ªHAT-P-2b, HAT-P-7b, *WASP-3b, and WASP-10b References: ª Hungarian Automated Telescope Network (HAT Net Project)Wide-Angle Search for Planets 12 PRE-OBSERVATION PLANNING It is essential for an observer to have specific information pertaining to the celestial object they intend to research through observation Generally, this information consists of the location for the object, field of view, date and time the object can be seen from Earth, and the instrumentation that should be used We needed this information for the observation of repeating transits HAT-P-2b, HAT-P-7b, WASP-3b, and WASP-10b The date and time of these transits were found by their ephemeris and periods; their locations were verified by the right ascensions (RA) and declinations (DEC) of their host stars; and their field of views were determined by the Orthogonal Parallel Transfer Imaging Camera (OPTIC) and the Nickel telescope Furthermore, comparison stars (section 2) and magnitudes of both the host and comparison stars were acquired This information is usually accessed from two sources: The Extrasolar Planets Encyclopaedia and The Aladin Sky Atlas Created in 1995, The Extrasolar Planets Encyclopaedia¹ is an interactive catalogue that consists of fifty two exoplanets This encyclopaedia has individual information about the host stars and extrasolar planets It includes data charts that have the right ascension and declination of the host star, the orbital period of the planet, the magnitude of the host star, and other pertinent information The Aladin Sky Atlas² created in 1999 is interactive software that allows one to visualize digitized images of any part of the sky, super impose entries from astronomical catalogs, and to interactively obtain related data and information References: ¹ The Extrasolar Planets Encyclopaedia exoplaneteu

3 -3- References: ² Aladin Sky Atlas 2 ALTERNATIVE EXTRASOLAR PLANETS CATALOGUE Observing in any case esteems time efficiency, accuracy, and sufficent knowledge of what is being observed highly; thus any improvements of such are sincerely appreciated One existing problem is the time consumption it takes to use different sources to gather the necessary information before observing repeating transits It can simply be a hassle A solution was to construct a combination of the two sources into another catalogue of Extrasolar Planet information Both sources offered unique information or detail that other did not The merging information of these sources comes together for thirty of the known transiting planets in the encyclopaedia The alternative catalogue presents a field of view, a table of comparison stars, and basic data charts The field of view³ is fitted for OPTIC* and Nickel* This field is where the best comparison stars are chosen for the host (target) star Figure 1 illustrates a field of view as seen in the alternative extrasolar planets catalogue

4 Figure 1 Field of view for HAT-P-7 in the Alternative Extrasolar Catalogue The 93 represents the OPTIC fitting and the 63 represents the Nickel fitting Also, the RA and Dec is in the upper left corner of the image -4- Following the field of view is the table of comparison stars These stars are exactly what the state, stars that are compared to the host star These stars can be standard stars or Cepheid objects They are used in the photometry process of the host stars The brightness or magnitudes of these comparison stars are needed to determine if they are the best comparison and the best for observation through your choice instrumentation The table gives detailed information about the comparison stars such as its distance from the host star in the field of view from Aladin, their magnitudes, RA and DEC in the field of view from Aladin, and any relative comments Figure 2 shows the comparison stars table for WASP-3 Dist Comparison Stars r' mag v mag x dist [RA] y dist [DEC] Comments 62' ' 136' Tycho Input Catalogue, Revised version (Egret+ 1992) 772' ' 432' Tycho Input Catalogue, Revised version (Egret+ 1992) 37' (VTmag) 25' 273' The Tycho-2 Catalogue (Hog+ 2000) 846' ' 462' 667' ' 21321'' 868' ' 852' Figure 2 A comparison stars table for WASP-3 as seen in the Alternative Extrasolar Catalogue

5 References: the expression ³ field of view ers to the patch of sky the observer views from their observation instrument * Orthogonal Parallel Transfer Imaging Camera * Nickel Telescope -5- Furthermore, information is given in the data charts provided from the Extrasolar Planets Encyclopaedia One chart gives the star s right ascension and declination, apparent magnitude, and other relevant information The information provided from these charts helps to create the field of view and collect the best comparison stars The other chart gives valuable information about the exoplanets such as the orbital period and radius Figure 3 and Figure 4 shows the data charts of the host star and extrasolar planet Star Name HAT-P-2 Distance 135 (± 16) pc Spectral Type F8 Apparent Magnitude V 871 Mass 1298 ( ) M s un Age 27 (± 14) Gyr Effective Temperatu re 6290 (± 110) K Radius 1416 ( ) R sun Metallicity [Fe/H] 011 (± 01) Right Asc Coord Decl Coord Figure 3 A basic data chart for HAT-P-2 as seen in the Alternative Extrasolar Catalogue

6 -6- PLANET Name HAT-P-2 b Discovered in 2007 Msin i 862 ( ) M J Semi major axis ( ) AU Orbital period (± ) days Eccentricity ( ) Omega ( ) deg Radius 0951 ( ) R J T peri ( ) Inclination 90 ( ) deg Update 27/03/08 Figure 4 A basic data chart for HAT-P-2b as seen in the Alternative Extrasolar Catalogue 3 RESULTS An advantage of having the Alternative Extrasolar Catalogue was the light curves produced for two of the exoplanets we observed: WASP-10 and WASP-3 Aforementioned, these light curves will be used to obtain redefined measurements of the planet s radius and average density and possibly more Figure 5 illustrates the light curve produce for the transit of WASP- 10 In addition, to theses results we were able to do pre observation planning for CoRoT-Exo-4 for the NOAO 2009 semester A Dr Johnson will be able to observe at least one out of three complete transits through OPTIC These

7 -7- transits are expected to happen February 24, 2009, March 05, 2009, and April 11, CONTINUATION AND BIASES The Alternative Extrasolar Catalogue is not publicly accessible Conceivably, in the near future this catalogue may me a webpage for the usage of observers Although, the catalogue will only have the most sufficiency for astronomers using OPTIC and Nickel to observe transiting extrasolar planets It will most likely only consist of 30 of the 307 extrasolar planets Nevertheless, this catalogue will be able to assist astronomers that research exoplanets through the Transit Method 4 ACKNOWLEDGEMENTS Special thanks are due to John A Johnson, Institute for Astronomy, and The National Science Foundation for making the 2008 Research Experience for Undergraduates University of Hawai i at Manoa possible REFERENCES G Torres, J N Winn, M J Holman 2008, arxiv: v3 [astro-ph] Winn, JN 2008, arxiv: v1 [astro-ph] S Aigrain, A Collier Cameron, M Ollivier, F Pont, L Jorda, J M Almenara, R Alonso, P Barge, P Borde et al, 2008, arxiv: v1 [astro-ph] Jean Schneider " Interactive Extra-solar Planets Catalog" The Extrasolar Planets Encyclopaedia 1995 CNRS-LUTH, Paris Observatory 2008 Centre de Données astronomiques de Strasbourg The Aladin Sky Atlas,1999 ULP/CNRS