¿ Astronomy Picture of the Day [1]Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2021 February 7 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Blue Straggler Stars in Globular Cluster M53 Image Credit: [3]ESA/Hubble, [4]NASA Explanation: If our Sun were part of this star cluster, the [5]night sky would glow like a jewel box of bright stars. This cluster, known as [6]M53 and cataloged as NGC 5024, is one of about 250 [7]globular clusters that survive in our Galaxy. Most of the stars in [8]M53 are older and redder than our Sun, but some enigmatic stars appear to be bluer and younger. These young [9]stars might contradict the hypothesis that all the stars in [10]M53 formed at nearly the same time. These unusual stars are known as [11]blue stragglers and are unusually common in M53. After much debate, [12]blue stragglers are now thought to be stars rejuvenated by fresh matter falling in from a binary star companion. By [13]analyzing pictures of globular clusters like the [14]featured image taken by the Hubble Space Telescope, astronomers [15]use the abundance of stars like [16]blue stragglers to help determine the age of the globular cluster and hence a [17]limit on the age of the universe. [18]M53, visible with a binoculars towards the [19]constellation of Bernice's Hair (Coma Berenices), contains over 250,000 stars and is one of the furthest [20]globulars from the center of our Galaxy. Tomorrow's picture: ripple stars __________________________________________________________________ [21]< | [22]Archive | [23]Submissions | [24]Index | [25]Search | [26]Calendar | [27]RSS | [28]Education | [29]About APOD | [30]Discuss | [31]> __________________________________________________________________ Authors & editors: [32]Robert Nemiroff ([33]MTU) & [34]Jerry Bonnell ([35]UMCP) NASA Official: Phillip Newman [36]Specific rights apply. [37]NASA Web Privacy Policy and Important Notices A service of: [38]ASD at [39]NASA / [40]GSFC & [41]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2102/m53_hubble_4131.jpg 3. https://www.spacetelescope.org/ 4. https://www.nasa.gov/ 5. https://en.wikipedia.org/wiki/Nightfall_(Asimov_short_story_and_novel) 6. https://en.wikipedia.org/wiki/Messier_53 7. https://apod.nasa.gov/apod/globular_clusters.html 8. http://gclusters.altervista.org/cluster_4.php?ggc=M+53 9. http://asterisk.apod.com/viewtopic.php?f=24&t=18009 10. https://www.nasa.gov/feature/goddard/2017/messier-53 11. http://www.solstation.com/x-objects/bluestrag.htm 12. https://astronomy.swin.edu.au/cosmos/b/blue+stragglers 13. https://ui.adsabs.harvard.edu/abs/1999AJ....118..453C/abstract 14. https://esahubble.org/images/potw1140a/ 15. https://en.wikipedia.org/wiki/Blue_straggler 16. https://apod.nasa.gov/apod/ap971104.html 17. http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question28.html 18. https://www.messier-objects.com/messier-53/ 19. http://www.ianridpath.com/startales/comaberenices.htm 20. https://en.wikipedia.org/wiki/Globular_clusters 21. https://apod.nasa.gov/apod/ap210206.html 22. https://apod.nasa.gov/apod/archivepix.html 23. https://apod.nasa.gov/apod/lib/apsubmit2015.html 24. https://apod.nasa.gov/apod/lib/aptree.html 25. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 26. https://apod.nasa.gov/apod/calendar/allyears.html 27. https://apod.nasa.gov/apod.rss 28. https://apod.nasa.gov/apod/lib/edlinks.html 29. https://apod.nasa.gov/apod/lib/about_apod.html 30. http://asterisk.apod.com/discuss_apod.php?date=210207 31. https://apod.nasa.gov/apod/ap210208.html 32. http://www.phy.mtu.edu/faculty/Nemiroff.html 33. http://www.phy.mtu.edu/ 34. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 35. http://www.astro.umd.edu/ 36. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 37. https://www.nasa.gov/about/highlights/HP_Privacy.html 38. https://astrophysics.gsfc.nasa.gov/ 39. https://www.nasa.gov/ 40. https://www.nasa.gov/centers/goddard/ 41. http://www.mtu.edu/