# Messier 90

Messier 90 (also known as M90 and NGC 4569) is an intermediate spiral galaxy exhibiting a weak inner ring structure about 60 million light-years away[a] in the constellation Virgo. It was discovered by Charles Messier in 1781.[3]

Observation dataEpoch J2000 Characteristics Messier 90 taken by Hubble Constellation Virgo[1] Right ascension 12h 36m 49.8s[2] Declination +13° 09′ 46″[2] Apparent dimension (V) 9.5 × 4.4 moa[2] Apparent magnitude (V) 10.26[2] Type SAB(rs)ab,[2] LINER,[2] Sy[2] −235 ± 4[2] km/s -0.000784 ± 0.000013[2] −282 ± 4[2] km/s 58.7 ± 2.8 Mly (18.00 ± 0.86 Mpc) NGC 4569,[2] UGC 7786,[2] PGC 42089,[2] Arp 76[2] SIMBAD Search M90 data

## Membership of the Virgo Cluster

Messier 90 is a member of the Virgo Cluster,[4] being one of its largest and brightest spiral galaxies, with an absolute magnitude of around -22 (brighter than the Andromeda Galaxy).[5] The galaxy is located approximately 1°.5 away from the subgroup centered on Messier 87.[6] As a consequence of the galaxy's interaction with the intracluster medium in the Virgo Cluster, the galaxy has lost much of its interstellar medium. As a result of this process, which is referred to as ram-pressure stripping, the galaxy's interstellar medium and star formation regions appear severely truncated compared to similar galaxies outside the Virgo Cluster[7] and there are even H II regions outside the galactic plane,[7] as well as long (up to 80 kpcs, 260,000 light-years) tails of ionized gas that has been stripped of M90.[8]

## Star formation activity

As stated above, the star formation in Messier 90 appears truncated. Consequently, the galaxy's spiral arms appear to be smooth and featureless, rather than knotted like galaxies with extended star formation.,[7] which justifies why this galaxy, along with NGC 4921 in the Coma Cluster has been classified as the prototype of an anemic galaxy.[9] Some authors go even further and consider it is a passive spiral galaxy, similar to those found on galaxy clusters with high redshift.[10]

However, the center of Messier 90 appears to be a site of significant star formation activity, where around 5*104 stars of spectral types O and B that formed around 5 to 6 million years ago[11] are surrounded by a large amount of A-type supergiants that were born in other starburst that took place before the former, between 15 and 30 million years ago.[12]

Multiple supernovae (up to 105[12]) in the nucleus have produced 'superwinds' that are blowing the galaxy's interstellar medium outward into the intracluster medium[13] collimated in two jets, one of which is being disturbed by interaction with Virgo's intracluster medium as the galaxy moves through it.[14]

## Blueshift

The spectrum of Messier 90 is blueshifted, which indicates that it is moving towards the Earth.[2] In contrast, the spectra of most other galaxies are redshifted. The blueshift was originally used to argue that Messier 90 was actually an object in the foreground of the Virgo Cluster. However, since the phenomenon was limited mostly to galaxies in the same part of the sky as the Virgo Cluster, it appeared that this inference based on the blueshift was incorrect. Instead, the blueshift is thought to be evidence for the large range in velocities of objects within the Virgo Cluster itself.[6]

## Distance measurements

Low levels of H I gas prevents using the Tully–Fisher relation to estimate the distance to Messier 90.[13]

## Companion galaxies

Messier 90 is rich in globular clusters, with around 1,000 of them[5] and has a satellite galaxy (IC 3583), which is an irregular galaxy.[citation needed] Both galaxies were thought to be interacting;[12] however, it is now thought they are too far away to be interacting at all.[8]

## Notes

1. ^ Tschöke et al. 2001 uses a Hubble constant of 75 (km/s)/Mpc to estimate a distance of 16.8 Mpc to NGC 4569. Adjusting for the 2006 value of 70+2.4
−3.2
(km/s)/Mpc we get a distance of 18.0+0.9
−0.6
Mpc.

## References

1. ^ R. W. Sinnott, ed. (1988). The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer. Sky Publishing Corporation/Cambridge University Press. ISBN 978-0-933346-51-2.
2. "NASA/IPAC Extragalactic Database". Results for NGC 4569. Retrieved 1 February 2006.
3. ^ K. G. Jones (1991). Messier's Nebulae and Star Clusters (2nd ed.). Cambridge University Press. ISBN 978-0-521-37079-0.
4. ^ B. Binggeli; A. Sandage; G. A. Tammann (1985). "Studies of the Virgo Cluster. II - A catalog of 2096 galaxies in the Virgo Cluster area. V - Luminosity functions of Virgo Cluster galaxies". The Astronomical Journal. 90: 1681–1759. Bibcode:1985AJ.....90.1681B. doi:10.1086/113874.
5. ^ a b "Globular Cluster Systems in Galaxies Beyond the Local Grup". NASA-IPAC Extragalactic Database (NED). Retrieved 21 July 2012.
6. ^ a b A. Sandage; J. Bedke (1994). Carnegie Atlas of Galaxies. Carnegie Institution of Washington. ISBN 978-0-87279-667-6.
7. ^ a b c R. A. Koopmann; J. D. P. Kenney (2004). "Hα Morphologies and Environmental Effects in Virgo Cluster Spiral Galaxies". Astrophysical Journal. 613 (2): 866–885. arXiv:astro-ph/0406243. Bibcode:2004ApJ...613..866K. doi:10.1086/423191.
8. ^ a b Boselli, A.; Cuillandre, J. C.; Fossati, M.; Boissier, S.; Bomans, D.; Consolandi, G.; Anselmi, G.; Cortese, L.; Cote, P.; Durrell, P.; Ferrarese, L.; Fumagalli, M.; Gavazzi, G.; Gwyn, S.; Hensler, G.; Sun, M.; Toloba, E. (2016). "Spectacular tails of ionised gas in the Virgo cluster galaxy NGC 4569" (PDF). Astronomy and Astrophysics. 587: A68. arXiv:1601.04978. Bibcode:2016A&A...587A..68B. doi:10.1051/0004-6361/201527795.
9. ^ Bergh, S. (1976). "A new classification system for galaxies". The Astrophysical Journal. 206: 883–887. Bibcode:1976ApJ...206..883V. doi:10.1086/154452.
10. ^ Moran, S. M.; Ellis, R. S.; Smith, G. P.; Rich, R. M.; et al. (2007). "A Wide-Field Survey of Two z ~ 0.5 Galaxy Clusters: Identifying the Physical Processes Responsible for the Observed Transformation of Spirals into S0s". The Astrophysical Journal. 671 (2): 1503–1522. arXiv:0707.4173. Bibcode:2007ApJ...671.1503M. doi:10.1086/522303.
11. ^ Gabel, J. R.; Bruhweiler, F. C. (2002). "The Central Starburst and Ionization Mechanism in the LINER/H II Region Transition Nucleus in NGC 4569". The Astronomical Journal. 124 (2): 737–750. arXiv:astro-ph/0204371. Bibcode:2002AJ....124..737G. doi:10.1086/341376.
12. ^ a b c Chyży, K. T.; Soida, M.; Bomans, D. J.; Vollmer, B.; et al. (2006). "Large-scale magnetized outflows from the Virgo Cluster spiral NGC 4569. A galactic wind in a ram pressure wind". Astronomy & Astrophysics. 447 (2): 465–472. arXiv:astro-ph/0510392. Bibcode:2006A&A...447..465C. doi:10.1051/0004-6361:20053819.
13. ^ a b D. Tschöke; D. J. Bomans; G. Hensler; N. Junkes (2001). "Hot halo gas in the Virgo cluster galaxy NGC 4569". Astronomy and Astrophysics. 380 (1): 40–54. Bibcode:2001A&A...380...40T. doi:10.1051/0004-6361:20011354.
14. ^ Kenney, J. D. P.; Crowl, H.; van Gorkom, J.; Vollmer, B. (2004). "Spiral Galaxy - ICM Interactions in the Virgo Cluster". International Astronomical Union Symposium No. 217. 217: 370–375. arXiv:astro-ph/0403129. Bibcode:2004IAUS..217..370K. doi:10.1017/S0074180900197979.