RX J0852.0−4622

{{Short description|Relatively young and nearby supernova remnant}}{{Supernova

| name = RX J0852.0−4622 or Vela Junior

| image = Supernova_Remnant_G266.2-1.2.jpg

| caption =The purple in this image is a false color indication of the x-rays detected by the Chandra X-Ray Observatory emanating from the edge of the supernova remnant due to a shockwave front. The center of the remnant is out of frame, off to the left.

| epoch = J2000.0

| type = SN

| SNRtype = CXOU J085201.4-461753

| host =

| constellation = Vela

| ra = {{RA|08|52}}

| dec = {{DEC|−46|22}}

| gal = 286.9460 +42.4568 (34" W, 10" S)

| discovery = 1998

| iauc =

| mag_v =

| distance = >1500 ly

| notes = central object in SNR RX J0852.0−4622 = AX J0851.9−4617. }}

RX J0852.0−4622 (also known as G266.2−1.2) is a supernova remnant. The remnant is located in the southern sky in the constellation Vela ("sail"), and sits (in projection) inside the much larger and older Vela Supernova Remnant. For this reason, RX J0852.0−4622 is often referred to as Vela Junior (Vela Jr.).SNRcat: [http://snrcat.physics.umanitoba.ca/SNRrecord.php?id=G266.2m01.2 Supernova Remnant G266.2-01.2]{{cite journal | url=https://iopscience.iop.org/article/10.1088/0004-637X/798/2/82 | doi=10.1088/0004-637X/798/2/82 | title=ON THE EXPANSION RATE, AGE, AND DISTANCE OF THE SUPERNOVA REMNANT G266.2–1.2 (Vela Jr.) | year=2014 | last1=Allen | first1=G. E. | last2=Chow | first2=K. | last3=Delaney | first3=T. | last4=Filipović | first4=M. D. | last5=Houck | first5=J. C. | last6=Pannuti | first6=T. G. | last7=Stage | first7=M. D. | journal=The Astrophysical Journal | volume=798 | issue=2 | page=82 | s2cid=11391141 | hdl=1721.1/94531 | hdl-access=free }} There have been a minority of suggestions that the remnant may be a spurious identification of a complicated substructure within the larger and better studied Vela SNR, but most studies accept that G266.2−1.2 is a SNR in its own right. Indeed, its detection in the high energy Teraelectronvolt range by the High Energy Stereoscopic System in 2005 is strong confirmation of such.{{Cite journal |last1=Aharonian |first1=F. |last2=Akhperjanian |first2=A. G. |last3=Bazer-Bachi |first3=A. R. |last4=Beilicke |first4=M. |last5=Benbow |first5=W. |last6=Berge |first6=D. |last7=Bernlöhr |first7=K. |last8=Boisson |first8=C. |last9=Bolz |first9=O. |last10=Borrel |first10=V. |last11=Braun |first11=I. |last12=Breitling |first12=F. |last13=Brown |first13=A. M. |last14=Chadwick |first14=P. M. |last15=Chounet |first15=L. -M. |date=2005-07-01 |title=Detection of TeV γ-ray emission from the shell-type supernova remnant RX J0852.0-4622 with HESS |url=https://ui.adsabs.harvard.edu/abs/2005A&A...437L...7A |journal=Astronomy and Astrophysics |volume=437 |issue=1 |pages=L7–L10 |doi=10.1051/0004-6361:200500130 |arxiv=astro-ph/0505380 |bibcode=2005A&A...437L...7A |issn=0004-6361}}

It was found in 1998 with an analysis of data from the ROSAT x-ray telescope.{{Cite journal |last=Aschenbach |first=B. |date=1998 |title=Discovery of a young nearby supernova remnant |url=http://user.astro.columbia.edu/~jules/C3273_10/aschenbach.pdf |journal=Nature |volume=396 |issue=6707 |pages=141–142 |bibcode=1998Natur.396..141A |doi=10.1038/24103 |s2cid=4426317}} Published simultaneously with its discovery was a claimed detection by the Compton Gamma Ray Observatory of a gamma ray spectral line of ⁴⁴Ti which has a half-life of 60 years and therefore seemed to indicate a young provenance for the supernova, perhaps the youngest one yet discovered.{{Cite journal |last1=Iyudin |first1=A. F. |last2=Schönfelder |first2=V. |last3=Bennett |first3=K. |last4=Bloemen |first4=H. |last5=Diehl |first5=R. |last6=Hermsen |first6=W. |last7=Lichti |first7=G. G. |last8=van der Meulen |first8=R. D. |last9=Ryan |first9=J. |last10=Winkler |first10=C. |date=1998-11-01 |title=Emission from 44Ti associated with a previously unknown Galactic supernova |url=https://ui.adsabs.harvard.edu/abs/1998Natur.396..142I |journal=Nature |volume=396 |issue=6707 |pages=142–144 |doi=10.1038/24106 |bibcode=1998Natur.396..142I |s2cid=4430526 |issn=0028-0836}} Later independent groups could not reproduce the detection, and so the consensus is that the identification of this line was likely spurious.{{Cite journal |last1=Slane |first1=Patrick |last2=Hughes |first2=John P. |last3=Edgar |first3=Richard J. |last4=Plucinsky |first4=Paul P. |last5=Miyata |first5=Emi |last6=Tsunemi |first6=Hiroshi |last7=Aschenbach |first7=Bernd |date=2001-02-01 |title=RX J0852.0-4622: Another Nonthermal Shell-Type Supernova Remnant (G266.2-1.2) |url=https://ui.adsabs.harvard.edu/abs/2001ApJ...548..814S |journal=The Astrophysical Journal |volume=548 |issue=2 |pages=814–819 |doi=10.1086/319033 |arxiv=astro-ph/0010510 |bibcode=2001ApJ...548..814S |issn=0004-637X}} Since the age and distance are correlated, a young, nearby supernova like this has inspired some detective work to identify evidence that such a supernova may have been observed and recorded by groups of people,{{Cite journal |last1=Aschenbach |first1=B. |last2=Iyudin |first2=A. F. |last3=Schönfelder |first3=V. |date=1999-10-01 |title=Constraints of age, distance and progenitor of the supernova remnant RX J0852.0-4622/GRO J0852-4642 |url=https://ui.adsabs.harvard.edu/abs/1999A&A...350..997A |journal=Astronomy and Astrophysics |volume=350 |pages=997–1006 |arxiv=astro-ph/9909415 |bibcode=1999A&A...350..997A |issn=0004-6361}} and geochronologists have looked for evidence of a young supernova in tree ringMichelle Starr: [https://www.sciencealert.com/traces-of-supernovae-could-be-locked-in-the-rings-of-ancient-trees The Rings of Ancient Trees May Hold Tales of Epic Space Explosions], on: science^alert, 14 November 2020 and ice core data,{{Cite journal |last1=Burgess |first1=C. P. |last2=Zuber |first2=K. |date=2000-08-01 |title=Footprints of the newly discovered Vela supernova in Antarctic ice cores? |url=https://www.sciencedirect.com/science/article/pii/S092765050000102X |journal=Astroparticle Physics |volume=14 |issue=1 |pages=1–6 |doi=10.1016/S0927-6505(00)00102-X |arxiv=astro-ph/9909010 |bibcode=2000APh....14....1B |s2cid=6392917 |issn=0927-6505}} but identification of claimed correlate signals have not been conclusively made. The latest analyses of the remnant indicate an age of at least 2400 years (and possibly much older), a distance of no less than 500 parsecs, and a radial size of at least 8 parsecs.

The central compact object (CCO) was discovered in 2001.{{Cite journal | last1 = Pavlov | first1 = G. G. | last2 = Sanwal | first2 = D. | last3 = Kiziltan | first3 = B.| last4 = Gairmire | first4 = G. P. | title = The Compact Central Object in the RX J0852.0−4622 Supernova Remnant | doi = 10.1086/323975 | journal = The Astrophysical Journal | volume = 559 | issue = 2 | pages = L131 | year = 2001 | bibcode=2001ApJ...559L.131P|arxiv = astro-ph/0108150 | s2cid = 8439326 }} In the initial Chandra X-ray image and deeper images thereafter, no pulsations were detected from the compact remnant, which is believed to be the neutron star CXOU J085201.4-461753. A different pulsar was suggested as the remnant,{{Cite journal |last1=Redman |first1=M. P. |last2=Meaburn |first2=J. |date=2005-01-01 |title=A possible association of a young pulsar (PSR J0855-4644) with the young Vela supernova remnant RX J0852.0-4622 |url=https://ui.adsabs.harvard.edu/abs/2005MNRAS.356..969R |journal=Monthly Notices of the Royal Astronomical Society |volume=356 |issue=3 |pages=969–973 |doi=10.1111/j.1365-2966.2004.08523.x |bibcode=2005MNRAS.356..969R |issn=0035-8711|doi-access=free }} but its kinematics do not conform as well to the observed kinematics of the remnant shell.