2MASS J04202144+2813491

Protoplanetary disk

The star's surrounding disk was first identified in 2009 as an infrared excess by Spitzer and was simultaneously resolved in I-band images from CFHT. Because the disk blocks the star’s light, it can be observed without a coronagraph. Its radius was initially measured at 2.5 arcseconds, equivalent to 350 astronomical units. The disk is classified as class II, meaning it contains both dust and gas but is more evolved than earlier class 0 or I disks. Depending on the model used, the dust mass is estimated between 163 and an unspecified upper value. Variability has been detected across optical to mid-infrared wavelengths.

The disk was first observed in carbon monoxide using the Five College Radio Astronomy Observatory. Archival ALMA data revealed a very edge-on disk, with CO extending to high altitudes above the disk plane. The continuum emission showed a radius similar to the optical size, while the CO radius was significantly larger. Further ALMA CO mapping showed the disk reaches up to 8 arcseconds, or 1000 AU, on the southern, blueshifted side; the northern, redshifted side is obscured by nebulosity, making the disk much larger than seen in optical and infrared. Strong evidence of dust settling exists: dust particles up to an unspecified size remain coupled to the gas up to the disk surface, while larger particles are found roughly ten times closer to the mid-plane. The inner disk is detected in CO and water emission with MIRI MRS, originating near 1 AU but scattered on dust out to 100 AU. MIRI MRS also resolved polycyclic aromatic hydrocarbons, previously seen in an unresolved Spitzer spectrum.

In 2014, Hubble ACS observations detected a Herbig-Haro object with clumps in a jet and counter-jet, extending up to 8 arcseconds from the star. The jet appears in a Hubble F606W image, primarily tracing H-alpha but possibly other emission lines. Additional emission lines from the jet were resolved with MIRI MRS, including ionized neon, iron, nickel, argon, and sulfur. The jet was also observed with NIRSpec in ionized iron emission. Its semi-opening angle was measured, though the value is not specified.