Weird Science

M109 - Vacuum Cleaner Galaxy

Polish ver­sion is here

Within the region of the sky mar­ked by the distinc­tive Big Dip­per aste­rism, part of the con­stel­la­tion Ursa Major, lies one of the more intri­gu­ing objects in the Mes­sier cata­log: M109, also known as NGC 3992. This bar­red spi­ral galaxy of mor­pho­lo­gi­cal type SBbc is loca­ted appro­xi­ma­tely 55 to 70 mil­lion light years from Earth. Its appa­rent magni­tude is about 9.8m, and its angu­lar dimen­sions mea­sure rou­ghly 7.6 arc­mi­nu­tes by 4.7 arc­mi­nu­tes. M109 is some­ti­mes infor­mally refer­red to as the Vacuum Cle­a­ner Galaxy.

The galaxy was disco­ve­red on March 12, 1781, by Pierre Méchain. Char­les Mes­sier cer­ta­inly obse­rved it as well, but it did not appear in the publi­shed edi­tion of his cata­log. In the 1950s, Ame­ri­can astro­no­mer Owen Jay Gin­ge­rich revi­si­ted Mes­sier’s cor­re­spon­dence and, based on histo­ri­cal evi­dence, incor­po­ra­ted seve­ral addi­tio­nal objects into the cata­log, among them M109.

M109 is a mas­sive spi­ral galaxy with a cen­tral bar-sha­ped struc­ture com­po­sed of stars. Two pri­mary spi­ral arms extend outward from this region and con­tain active sites of ongo­ing star for­ma­tion. The bar plays a key role in the inter­nal dyna­mics of the galaxy because it pro­mo­tes the inward tran­s­port of gase­ous mate­rial toward the cen­tral regions, the­reby influ­en­cing the evo­lu­tio­nary deve­lop­ment of the nuc­leus. At an adop­ted distance of rou­ghly 60 mil­lion light years, the galaxy’s linear dia­me­ter is esti­ma­ted to be between 120,000 and 130,000 light years, making it com­pa­ra­ble in scale to the Milky Way.

M109 is the bri­gh­test mem­ber of a small gra­vi­ta­tio­nally bound sys­tem known as the M109 Group. Seve­ral smal­ler satel­lite gala­xies reside in its imme­diate vici­nity, and their gra­vi­ta­tio­nal inte­rac­tions with the pri­mary galaxy may con­tri­bute to sub­tle distor­tions in the mor­pho­logy and struc­ture of its spi­ral arms.

Obse­rva­tions

March 02, 2025, about 10:00 p.m. - Kato­wice, Poland
urban con­di­tions, very high level of light pol­lu­tion

M109 lies in close pro­xi­mity to the star Phecda, γ Ursae Majori, one of the four stars that outline the bowl of the Big Dip­per. Owing to the nor­thern dec­li­na­tion of Ursa Major, the galaxy is well pla­ced for obse­rva­tion from Poland and other mid-nor­thern lati­tu­des. The most favo­ra­ble con­di­tions occur during the spring mon­ths, when the con­stel­la­tion cul­mi­na­tes high above the hori­zon during the eve­ning hours. Because of its mode­rate sur­face bri­ght­ness, M109 repre­sents an attrac­tive yet tech­ni­cally deman­ding pho­to­gra­phic tar­get. Reve­a­ling clear spi­ral struc­ture typi­cally requ­i­res total expo­sure times mea­su­red in hours. Under good sky con­di­tions, seve­ral faint back­gro­und gala­xies, as well as satel­lite mem­bers of the M109 Group, can also be recor­ded in the same field of view (Photo 1).

Ilustracja: Photo. 1 - whithout labels

Photo. 1 - whithout labels

Ilustracja: Photo. 1 - whith labels

Photo. 1 - whith labels

Bar­red spi­rals like M109 pro­vide cru­cial insi­ghts into the evo­lu­tion of galac­tic archi­tec­ture. Nume­ri­cal simu­la­tions sug­gest these bars emerge from dyna­mi­cal insta­bi­li­ties within the disk or are trig­ge­red by gra­vi­ta­tio­nal enco­un­ters with com­pa­nion gala­xies. By obse­rving M109 across infra­red and radio wave­leng­ths, rese­ar­chers can map mole­cu­lar gas distri­bu­tion and trace star-for­ming acti­vity along its spi­ral arms. Fur­ther­more, the galaxy serves as a com­pel­ling labo­ra­tory for stu­dy­ing galac­tic nuc­lei and cen­tral dyna­mics.

Photo 1 Para­me­ters:

  • total expo­sure time: 200 minu­tes (stack of 400 RAW fra­mes at 30s each, using an appro­priate num­ber of dark, bias, and flat fra­mes)
  • ISO: 1600
  • Mak­su­tov-Cas­se­grain tele­scope (100/1400), prime focus expo­sure
  • A fil­ter was used to reduce the effects of arti­fi­cial light pol­lu­tion and atmo­sphe­ric glow
  • Mount: equ­a­to­rial mount with trac­king, ali­gned using the drift method and con­trol­led by a custom-built sys­tem.

Fur­ther rea­dings:

Marek Ples

Aa