Editing RR Lyrae variable (section)

==Recent developments==
The [[Hubble Space Telescope]] has identified several RR Lyrae candidates in globular clusters of the [[Andromeda Galaxy]]<ref name="clementini"/> and has measured the distance to the prototype star RR Lyrae.<ref name=hst>{{cite journal | display-authors=1 | last1=Benedict | first1=G. Fritz | last2=McArthur | first2=B. E. | last3=Fredrick | first3=L. W. | last4=Harrison | first4=T. E. | last5=Lee | first5=J. | last6=Slesnick | first6=C. L. | last7=Rhee | first7=J. | last8=Patterson | first8=R. J. | last9=Nelan | first9=E. | title=Astrometry with the Hubble Space Telescope: A Parallax of the Fundamental Distance Calibrator RR Lyrae | journal=The Astronomical Journal | volume=123 | issue=1 | pages=473–484 |date=January 2002 | doi=10.1086/338087 | bibcode=2002AJ....123..473B |arxiv = astro-ph/0110271 | s2cid=59150013 }}</ref>

The [[Kepler space telescope]] provided accurate [[photometry (astronomy)|photometric]] coverage of a single field at regular intervals over an extended period. 37 known RR Lyrae variables lie within the Kepler field, including RR Lyrae itself, and new phenomena such as period-doubling have been detected.<ref>{{cite journal|bibcode=2011rrls.conf...74K|arxiv=1107.0297|title=RR Lyrae Research with the Kepler Mission|journal=RR Lyrae Stars|volume=5|pages=74|last1=Kinemuchi|first1=Karen|year=2011}}</ref>

The [[Gaia mission]] mapped 140,784 RR Lyrae stars, of which 50,220 were not previously known to be variable, and for which 54,272 [[Extinction (astronomy)|interstellar absorption]] estimates are available.<ref>{{Cite journal|last1=Riello|first1=M.|last2=Evans|first2=D. W.|last3=Szabados|first3=L.|last4=Sarro|first4=L. M.|last5=Regibo|first5=S.|last6=Ridder|first6=J. De|last7=Eyer|first7=L.|last8=Lecoeur-Taibi|first8=I.|last9=Mowlavi|first9=N.|date=2019-02-01|title=Gaia Data Release 2 - Specific characterisation and validation of all-sky Cepheids and RR Lyrae stars|journal=Astronomy & Astrophysics|language=en|volume=622|pages=A60|doi=10.1051/0004-6361/201833374|issn=0004-6361|arxiv=1805.02079|bibcode=2019A&A...622A..60C|s2cid=260496633 }}</ref>

The [[Pan-STARRS|PanSTARRS1]] 3π survey identified ~45,000 RR Lyrae stars, representing the widest (covering 3/4 of the sky) and deepest (reaching up to 120 kpc) sample of RR Lyrae stars to date. In 2017, Sesar et al. used these stars to develop a novel template-fitting technique, achieving highly accurate period estimates with precision better than 2 seconds in over 80% of cases.<ref>{{Cite journal |last1=Sesar |first1=Branimir |title=Machine-learned Identification of RR Lyrae Stars from Sparse, Multi-band Data: The PS1 Sample |date=2017-03-07 |arxiv=1611.08596 |last2=Hernitschek |first2=Nina |last3=Mitrović |first3=Sandra |last4=Ivezić |first4=Željko |last5=Rix |first5=Hans-Walter |last6=Cohen |first6=Judith G. |last7=Bernard |first7=Edouard J. |last8=Grebel |first8=Eva K. |last9=Martin |first9=Nicolas F.|journal=The Astronomical Journal |volume=153 |issue=5 |page=204 |doi=10.3847/1538-3881/aa661b |doi-access=free |bibcode=2017AJ....153..204S }}</ref>

The [[Dark Energy Survey]] (DES) was used to identify ~6000 RR Lyrae candidates in the southern sky , ~31% of which are previously undiscovered. The survey also improved period-luminosity relations, advancing distance measurements and studies of galactic structure.<ref>{{Cite journal |last1=Stringer |first1=K. M. |title=Identification of RR Lyrae Stars in Multiband, Sparsely Sampled Data from the Dark Energy Survey Using Template Fitting and Random Forest Classification |date=2019-05-01 |last2=Long |first2=J. P. |last3=Macri |first3=L. M. |last4=Marshall |first4=J. L. |last5=Drlica-Wagner |first5=A. |last6=Martínez-Vázquez |first6=C. E. |last7=Vivas |first7=A. K. |last8=Bechtol |first8=K. |last9=Morganson |first9=E.|journal=The Astronomical Journal |volume=158 |issue=1 |page=16 |doi=10.3847/1538-3881/ab1f46 |doi-access=free |arxiv=1905.00428 |bibcode=2019AJ....158...16S }}</ref>

Feng et al.] (2024) used the Next Generation Virgo Cluster Survey to identify 180 faint RR Lyrae candidates (~21 mag) at galactocentric distances of ~20–300 kpc, with ~100 not previously cataloged in PanSTARRS1 (PS1). The study applied empirical pulsation fitting techniques, originally developed for the [[Sloan Digital Sky Survey]] (SDSS), to analyze these candidates.<ref>{{Cite journal |last1=Feng |first1=Yuting |last2=Guhathakurta |first2=Puragra |last3=Peng |first3=Eric W. |last4=Gwyn |first4=Stephen D. J. |last5=Ferrarese |first5=Laura |last6=Côté |first6=Patrick |last7=Cuillandre |first7=Jean-Charles |last8=Munsell |first8=Jane |last9=Talukdar |first9=Manjima |date=May 2024 |title=The Next Generation Virgo Cluster Survey. XXXVII. Distant RR Lyrae Stars and the Milky Way Stellar Halo Out to 300 kpc |journal=The Astrophysical Journal |language=en |volume=966 |issue=2 |pages=159 |doi=10.3847/1538-4357/ad2ae7 |doi-access=free |issn=0004-637X|arxiv=2402.05418 |bibcode=2024ApJ...966..159F }}</ref>

RR Lyrae pulsational parameters from the [[Dark Energy Survey]] (DES), [[Pan-STARRS|Pan-STARRS 1]] (PS1) and the Next Generation Virgo Cluster Survey were validated and refined using the [[Subaru Telescope|Hyper Suprime-Cam Subaru Strategic Survey]]. [[W. M. Keck Observatory|Keck II's ESI spectrograph]] was also used to analyze spectra of distant Milky Way halo RR Lyrae candidates to identify background [[quasar]] contaminants in previously mentioned surveys.<ref>{{Cite journal |last1=Sridhara |first1=Shravan Calvin |last2=Thomas |first2=Ethan |last3=Dong |first3=Hannibal |last4=Chenrayan |first4=Meiyappa Sugam |last5=Guhathakurta |first5=Puragra |last6=Feng |first6=Yuting |last7=Peng |first7=Eric |title=Identification of Faint Quasars via Spectroscopy of Distant Milky Way Halo RR Lyrae Candidates |journal=American Astronomical Society Meeting Abstracts |date=2025 |volume=245 |bibcode=2025AAS...24547004S }}</ref><ref>{{Cite journal |last1=Kappagantula |first1=Chandrasekhar |last2=Gilligan |first2=Finn |last3=Chen |first3=Sihan |last4=Feng |first4=Yuting |last5=Guhathakurta |first5=Puragra |last6=Peng |first6=Eric |last7=Komiyama |first7=Yutaka |title=Testing the Classification and Verifying the Pulsational Parameters of RR Lyrae candidates using a pilot sample of Hyper Suprime-Cam survey data |journal=American Astronomical Society Meeting Abstracts |date=2025 |volume=245 |bibcode=2025AAS...24547003K }}</ref><ref>{{Cite journal |last1=Ingkasampan |first1=Rasmiwan (Pear) |last2=Anand |first2=Anya |last3=Pramanik |first3=Chetana |last4=Agarwal |first4=Tannuvi |last5=Feng |first5=Yuting |last6=Guhathakurta |first6=Puragra |last7=Peng |first7=Eric |title=Testing the Performance of a RR Lyrae Light Curve Template Fitting Algorithm |journal=American Astronomical Society Meeting Abstracts |date=2025 |volume=245 |bibcode=2025AAS...24547006I }}</ref>