Messier 71

{{short description|Globular cluster in the constellation Sagitta}}

{{Multiple issues|

}}

{{Infobox globular cluster

| name = Messier 71

| image = Messier 71, an Unusual Globular Cluster.jpg

| caption = The globular cluster Messier 71 by the Hubble Space Telescope.

| credit =

| epoch = J2000

| class = X-XI

| constellation = Sagitta

| ra = {{RA|19|53|46.49}}

| dec = {{DEC|+18|46|45.1}}

| dist_ly = {{Convert|13.0|kly|kpc|abbr=on|lk=on}}

| appmag_v = 8.2{{cite web |url=https://messier.seds.org/m/m071.html |title=Messier 71 |access-date=30 April 2022 |website=SEDS Messier Catalog}}

| size_v = 7.2'

| mass_msol = {{Val|1.7|e=4}}

| radius_ly = 13 lydistance × sin( diameter_angle / 2 ) = 13 ly. radius

| metal_fe = –0.78

| v_hb =

| age = 9-10 Gyr

| notes =

| names = M71, NGC 6838, Cr 409, GCl 115

}}

Messier 71 (also known as M71, NGC 6838, or the Angelfish Cluster) is a globular cluster in the small northern constellation Sagitta. It was discovered by Philippe Loys de Chéseaux in 1745 and included by Charles Messier in his catalog of non-comet-like objects in 1780. It was also noted by Koehler at Dresden around 1775.{{Cite web|title=New General Catalog Objects: NGC 6800 - 6849|url=https://cseligman.com/text/atlas/ngc68.htm#6838|access-date=2021-03-11|website=cseligman.com}} Messier 71 is also known as NGC 6839, though this identification is very uncertain.{{Cite web |title=Your NED Search Results |url=https://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=NGC_6839&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES |access-date=2024-08-28 |website=ned.ipac.caltech.edu}}

This star cluster is about 13,000 light years away from Earth and spans {{convert|27|ly|pc|0}}. The irregular variable star Z Sagittae is a member.

File:M71 Crop.pngM71 was for many decades thought (until the 1970s) to be a densely packed open cluster and was classified as such by leading astronomers in the field of star cluster research due to its lacking a dense central compression, and to its stars having more "metals" than is usual for an ancient globular cluster; furthermore, it lacks the RR Lyrae "cluster" variable stars that are common in most globulars. However, modern photometric photometry has detected a short "horizontal branch" in the H-R diagram (chart of temperature versus luminosity) which is characteristic of a globular cluster. The shortness of the branch explains the lack of RR Lyrae variables and is due to the globular's relatively young age of 9–10 billion years. Taking in many or only late series (Population I) stars explains relatively its stars. Hence today M71 is designated as a very loosely concentrated globular cluster, much like M68 in Hydra. M71 has a mass of about {{solar mass|53,000|link=yes}} and a luminosity of around 19,000 {{lo|link=yes}}.

File:M71map.png

References

{{reflist|refs=

{{citation | display-authors=1 | last1=Goldsbury | first1=Ryan | last2=Richer | first2=Harvey B. | last3=Anderson | first3=Jay | last4=Dotter | first4=Aaron | last5=Sarajedini | first5=Ata | last6=Woodley | first6=Kristin | title=The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters | journal=The Astronomical Journal | volume=140 | issue=6 | pages=1830–1837 |date=December 2010 | doi=10.1088/0004-6256/140/6/1830 | bibcode=2010AJ....140.1830G | postscript=. |arxiv = 1008.2755 | s2cid=119183070 }}

{{citation | last1=Marks | first1=Michael | last2=Kroupa | first2=Pavel | title=Initial conditions for globular clusters and assembly of the old globular cluster population of the Milky Way | journal=Monthly Notices of the Royal Astronomical Society | volume=406 | issue=3 | pages=2000–2012 |date=August 2010 | doi=10.1111/j.1365-2966.2010.16813.x | doi-access=free | bibcode=2010MNRAS.406.2000M | postscript=. |arxiv = 1004.2255 | s2cid=118652005 }} Mass is from M_PD on Table 1.

{{citation | display-authors=1 | last1=Hessels | first1=J. W. T. | last2=Ransom | first2=S. M. | last3=Stairs | first3=I. H. | last4=Kaspi | first4=V. M. | last5=Freire | first5=P. C. C. | title=A 1.4 GHz Arecibo Survey for Pulsars in Globular Clusters | journal=The Astrophysical Journal | volume=670 | issue=1 | pages=363–378 |date=November 2007 | doi=10.1086/521780 | bibcode=2007ApJ...670..363H | postscript=. |arxiv = 0707.1602 | s2cid=16914232 }}

{{citation | display-authors=1 | last1=Boyles | first1=J. | last2=Lorimer | first2=D. R. | last3=Turk | first3=P. J. | last4=Mnatsakanov | first4=R. | last5=Lynch | first5=R. S. | last6=Ransom | first6=S. M. | last7=Freire | first7=P. C. | last8=Belczynski | first8=K. | title=Young Radio Pulsars in Galactic Globular Clusters | journal=The Astrophysical Journal | volume=742 | issue=1 | page=51 |date=November 2011 | doi=10.1088/0004-637X/742/1/51 | bibcode=2011ApJ...742...51B | postscript=. |arxiv = 1108.4402 | s2cid=118649860 }}

{{cite web |title=Z Sge |url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=27350 |website=The International Variable Star Index |publisher=AAVSO |access-date=1 March 2021}}

{{cite journal |last1=Dalgleish |first1=H. |last2=Kamann |first2=S. |last3=Usher |first3=C. |last4=Baumgardt |first4=H. |last5=Bastian |first5=N. |last6=Veitch-Michaelis |first6=J. |last7=Bellini |first7=A. |last8=Martocchia |first8=S. |last9=Da Costa |first9=G. S. |last10=Mackey |first10=D. |last11=Bellstedt |first11=S. |last12=Pastorello |first12=N. |last13=Cerulo |first13=P. |title=The WAGGS project-III. Discrepant mass-to-light ratios of Galactic globular clusters at high metallicity |journal=Monthly Notices of the Royal Astronomical Society |date=March 2020 |volume=492 |issue=3 |pages=3859–3871 |doi=10.1093/mnras/staa091 |bibcode=2020MNRAS.492.3859D |doi-access=free |arxiv=2001.01810 }}

}}

Gallery

File:M71.jpg|Till Credner and Sven Kohle, Calar Alto Observatory.

File:M71 - Noao-m71.jpg|M71 in visible light by the NOAO.

File:NGC 6838 2MASS.jpg|M71 in infrared by the survey 2MASS.

File:NGC 6838 DSS.jpg|M71 in visible light by the survey DSS.

External links

{{WikiSky}}
[http://messier.seds.org/m/m071.html Messier71 @ SEDS Messier pages]
[http://gclusters.altervista.org/cluster_4.php?ggc=M+71 Messier 71, Galactic Globular Clusters Database page]
[http://www.perseus.gr/Astro-DSO-NGC-6838.htm Messier 71, LRGB CCD image based on two hours total exposure]
[https://esahubble.org/images/potw1018a/ Messier 71: an Unusual Globular Cluster], ESA\Hubble picture of the week.
{{cite web|title=M71 – Globular Cluster|url=http://www.deepskyvideos.com/videos/messier/M71.html|work=Deep Sky Videos|publisher=Brady Haran|author=McCormac, James|author2=Szymanek, Nik |author-link2=Nik Szymanek }}

Messier 071

071

Messier 071

Messier 71

See also

References

Gallery

External links