LSPM J0207+3331

{{Starbox image

| image = 300px

| caption = Artist's impression

| credit = NASA’s Goddard Space Flight Center/Scott Wiessinger

}}

{{Starbox observe

| epoch = J2000

| constell = Triangulum

| ra = {{RA|02|07|33.8061}}

| dec = {{DEC|+33|31|29.542}}

}}

{{Starbox character

|type=white dwarf

|class=DA

|appmag_1_passband=g

|appmag_1=17.86 ± 0.02

|appmag_2_passband=r

|appmag_2=17.49 ± 0.02

|appmag_3_passband=i

|appmag_3=17.34 ± 0.02

|appmag_4_passband=J

|appmag_4={{val|16.6|0.1}}

}}

{{Starbox astrometry

| radial_v =

| prop_mo_ra = {{val|169.843|(151)}}

| prop_mo_dec = {{val|−25.850|(202)}}

| pm_footnote =

| parallax = 22.4986

| p_error = 0.1563

| parallax_footnote =

| absmag_v =

}}

{{Starbox detail

| mass={{val|0.69|0.01|0.02}}

| temperature={{val|6120|48|57}}

| age_gyr={{val|3|0.2}}

| radius=0.011

| gravity={{val|8.16|0.03}}

}}

{{Starbox catalog

| names = {{odlist | 2MASS=J02073383+3331296 | Gaia DR3=325899163483416704 }}

}}

{{Starbox reference

| Simbad=LSPM+J0207%2B3331

}}

LSPM J0207+3331 is a cold and old white dwarf that hosts a circumstellar disk, located 145 light-years from Earth. It was discovered in October 2018 by a volunteer participating in the Backyard Worlds citizen science project.{{cite web|url=https://svs.gsfc.nasa.gov/13147|title=Volunteer Discovers Record-Setting White Dwarf Star|date=19 February 2019|website=NASA.gov|accessdate=22 February 2019}}{{cite web|url=https://www.noao.edu/news/2019/pr1904.php|title=Citizen Scientists Invited to Join Quest for New Worlds|website=NOAO|accessdate=22 February 2019}} Until 2021 it was the oldest and coldest white dwarf known to host a disk. The white dwarf WD 2317+1830 with a detected disk is at least twice as old and around 2,000 K colder.{{Cite journal |last1=Hollands |first1=Mark A. |last2=Tremblay |first2=Pier-Emmanuel |last3=Gänsicke |first3=Boris T. |last4=Koester |first4=Detlev |last5=Gentile-Fusillo |first5=Nicola Pietro |date=2021-05-01 |title=Alkali metals in white dwarf atmospheres as tracers of ancient planetary crusts |url=https://ui.adsabs.harvard.edu/abs/2021NatAs...5..451H/abstract |journal=Nature Astronomy |volume=5 |issue=5 |pages=451–459 |arxiv=2101.01225 |bibcode=2021NatAs...5..451H |doi=10.1038/s41550-020-01296-7 |issn=2397-3366}}{{Cite journal |last1=Bergeron |first1=P. |last2=Kilic |first2=Mukremin |last3=Blouin |first3=Simon |last4=Bédard |first4=A. |last5=Leggett |first5=S. K. |last6=Brown |first6=Warren R. |date=2022-07-01 |title=On the Nature of Ultracool White Dwarfs: Not so Cool after All |journal=The Astrophysical Journal |volume=934 |issue=1 |pages=36 |arxiv=2206.03174 |bibcode=2022ApJ...934...36B |doi=10.3847/1538-4357/ac76c7 |doi-access=free |issn=0004-637X}}

The white dwarf has a radius of {{Solar radius|0.011|link=y}}, which is about 1.2 times the radius of the earth. Because white dwarfs are such dense objects, LSPM J0207 has a mass of about 0.69 {{Solar mass|link=true}}. The presence of the Paschen Beta-Line in a near-infrared spectrum from the Keck telescope helped to determine that the atmosphere of LSPM J0207 is dominated by hydrogen (spectral type DA). Due to the inner disk around the white dwarf, it should be expected that the atmosphere has a lot of other elements and that it is a metal-polluted white dwarf. To confirm this hypothesis, it is required to take an optical spectrum of the white dwarf.

Debris disk

The star has a circumstellar disk despite being 3 billion years old. The infrared excess in the spectrum is consistent with two rings at different temperatures: an outer colder ring with a temperature of {{val|480|ul=K}} and an inner ring with a temperature between 550–{{val|1400|u=K}}. It may be a debris disk created from asteroids broken apart by the star's gravity.

The inner disk is optically thick with an inner radius of {{Solar radius|0.047}} and an outer radius of {{Solar radius|0.21}}. The outer disk is optically thin. It is located near the Roche radius at around {{Solar radius|0.94}} and has a mass of a small asteroid or comet. This suggests that the outer disk formed relative recently from a tidal disruption of such a small body. If this outer disk is confirmed, it would be the first known dusty white dwarf with a two-component ring system. Alternatively the gap in the disk could be explained by a dense exoplanet orbiting inside the disk and clearing a gap, or a planet orbiting outside the disk and opening a gap via resonant dynamics.{{cite journal|last1=Steckloff|first1=Jordan K.|last2=Debes|first2=John|last3=Steele|first3=Amy|last4=Johnson|first4=Brandon|last5=Adams|first5=Elisabeth R.|last6=Jacobson|first6=Seth A.|last7=Springmann|first7=Alessondra|date=2021-04-28|title=How Sublimation Delays the Onset of Dusty Debris Disk Formation around White Dwarf Stars|journal=The Astrophysical Journal Letters|volume=913|issue=2|pages=L31|doi=10.3847/2041-8213/abfd39|pmid=35003618|pmc=8740607|arxiv=2104.14035|bibcode=2021ApJ...913L..31S |doi-access=free }}

Due to the inner edge of the inner disk being located near the sublimation radius of fayalite and iron, it is suggested that the inner disk is composed of these materials. It is however not excluded that forsterite is a component of the inner disk. One work used photometry of the Astrophysical Observatory of Javalambre of the J-PLUS survey to predict a 89.7% chance of the white dwarf having absorption due to calcium, which is seen as material from an asteroid that is polluting the atmosphere of the white dwarf.{{Cite journal |last=López-Sanjuan |first=C. |last2=Tremblay |first2=P.-E. |last3=O'Brien |first3=M. W. |last4=Spinoso |first4=D. |last5=Ederoclite |first5=A. |last6=Vázquez Ramió |first6=H. |last7=Cenarro |first7=A. J. |last8=Marín-Franch |first8=A. |last9=Civera |first9=T. |last10=Carrasco |first10=J. M. |last11=Gänsicke |first11=B. T. |last12=Gentile Fusillo |first12=N. P. |last13=Hernán-Caballero |first13=A. |last14=Hollands |first14=M. A. |last15=del Pino |first15=A. |date=November 2024 |title=J-PLUS: The fraction of calcium white dwarfs along the cooling sequence |url=https://ui.adsabs.harvard.edu/abs/2024A&A...691A.211L/abstract |journal=Astronomy and Astrophysics |language=en |volume=691 |pages=A211 |arxiv=2406.16055 |bibcode=2024A&A...691A.211L |doi=10.1051/0004-6361/202451226 |issn=0004-6361}}

Models predict only a low rate of asteroids to be disrupted by an old white dwarf. The 1 Gyr simulations by Debes et al. found that only one asteroid per simulation was disrupted 200 Myrs after the white dwarf has formed.{{Cite journal|last1=Debes|first1=John H.|last2=Walsh|first2=Kevin J.|last3=Stark|first3=Christopher|date=2012-03-01|title=The Link between Planetary Systems, Dusty White Dwarfs, and Metal-polluted White Dwarfs|journal=The Astrophysical Journal|volume=747|issue=2|pages=148|doi=10.1088/0004-637X/747/2/148|arxiv=1201.0756|bibcode=2012ApJ...747..148D|s2cid=118688656|issn=0004-637X}} The presence of a disk around a 3 Gyr white dwarf sets new demands for models that seek to explain dust around white dwarfs.{{cite journal|arxiv=1902.07073|last1=Debes|first1=John H.|title=A 3 Gyr White Dwarf with Warm Dust Discovered via the Backyard Worlds: Planet 9 Citizen Science Project| last2=Thevenot| first2=Melina| last3=Kuchner| first3=Marc| last4=Burgasser| first4=Adam| last5=Schneider| first5=Adam| last6=Meisner| first6=Aaron| last7=Gagne| first7=Jonathan| last8=Faherty| first8=Jaqueline K.| last9=Rees| first9=Jon M.| last10=Allen| first10=Michaela| last11=Caselden| first11=Dan| last12=Cushing| first12=Michael| last13=Wisniewski| first13=John| last14=Allers| first14=Katelyn| author15=The Backyard Worlds: Planet 9 Collaboration| author16=The Disk Detective Collaboration| journal=The Astrophysical Journal| year=2019| volume=872| issue=2| pages=L25| doi=10.3847/2041-8213/ab0426|bibcode=2019ApJ...872L..25D| s2cid=119359995 |doi-access=free }}

References

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J02073383+3331296

Category:Astronomical objects discovered in 2018

Category:Circumstellar disks

Category:TIC objects

Category:Triangulum

Category:White dwarfs

LSPM J0207+3331

Debris disk

See also

References