Using the Palomar Transient Factory to search for ultra-long-period Cepheid candidates in M21

Chien Hsiu Lee, Chow Choong Ngeow, Michael Ting Chang Yang, Wing Huen Ip, Albert Kwok Hing Kong, Russ R. Laher, Jason Surace

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

Ultra-long-period Cepheids (ULPCs) are important in distance-scale studies due to their potential for determining distance beyond ∼ 100 Mpc. We performed a comprehensive search for ULPCs in M31, a local benchmark to calibrate the distance ladders. We use data from the Palomar Transient Factory (PTF), which has imaged M31 using a 1.2-m telescope equipped with a ≈7.26 deg2 field-of-view (FOV) camera, usually with daily sampling, since the beginning of 2010. The large FOV, together with the regular monitoring, enables us to probe ULPCs in the bulge, disk, and even out to the halo of M31. Using a difference imaging analysis technique, we found and characterized 3 promising ULPC candidates based on their luminosities, amplitudes and Fourier parameters. The mean absolute magnitude for these 3 ULPC candidates, calibrated with latest M31 distance, is MR = 6.47mag. Two out of the 3 ULPC candidates have been reported in literature, however their published periods from Magnier et al. are about half of the periods we found in this work. The third ULPC candidate is a new discovery. We studied 5 other candidates and determined that they are probably Mira-like or ultra-long-period variables, but not ULPCs.

Original languageEnglish
Title of host publicationInternational Conference on Space Science and Communication, IconSpace
Pages1-6
Number of pages6
DOIs
StatePublished - 2013
Event2013 3rd IEEE International Conference on Space Science and Communication, IconSpace 2013 - Melaka, Malaysia
Duration: 1 Jul 20133 Jul 2013

Publication series

NameInternational Conference on Space Science and Communication, IconSpace
ISSN (Print)2165-4301
ISSN (Electronic)2165-431X

Conference

Conference2013 3rd IEEE International Conference on Space Science and Communication, IconSpace 2013
Country/TerritoryMalaysia
CityMelaka
Period1/07/133/07/13

Keywords

  • Cepheids
  • Distance scale
  • Galaxies
  • individual (M31)
  • Optical astronomy
  • Time-domain astronomy

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