HD 44892: The youngest (or oldest?) gas-harbouring debris disc around an intermediate mass star

Abstract

We present the first detections of gas around a 2.1 Myr old debris disc-bearing intermediate-mass star, HD 44892. Gas is detected both in ${}^{12}$CO (2-1) emission through ALMA Band 6 observations and in absorption in Ca II K and H, seen with high-resolution UVES spectroscopy. ${}^{13}$CO and C${}^{18}$O (2-1) are not detected. The star exhibits a 12 $\mu$m fractional excess of $7.86_{-2.27}^{+0.11}$, placing it in the transition stage between protoplanetary and debris discs. Our detection of 1.3 mm emission yields the dust mass of 0.019$\pm$0.009 $M_{\oplus }$ assuming 115 K temperature. The ${}^{13}$CO non-detection places an upper limit on CO gas mass of $\sim$10${}^{-2}$ $M_{\oplus }$. The ${}^{12}$CO detection yields a CO gas mass of (7.86$\pm$2.05)$\times$10${}^{-5}$ $M_{\oplus }$ or (1.62$\pm$0.17)$\times$10${}^{-4}$ $M_{\oplus }$ assuming a gas temperature of 20 K or 50 K, respectively. These should be considered as lower limits since ${}^{12}$CO emission may be optically thick. With UVES, we find variability in Ca II K and H lines, which can be interpreted by transiting circumstellar gas, ruling out interstellar absorption as their origin. Both the dust mass, which is within an order of magnitude of HD 141569, and the gas mass derived here indicate a late gas dispersal stage of the protoplanetary disc. Through our analysis we deem the alternative age of 800 Myr unlikely.

References in corpus (45)

• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra
• Pulkovo Compilation of Radial Velocities for 35495 Hipparcos Stars in a Common System
• Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$ Pictoris Debris Disk
• Detection of exocometary CO within the 440 Myr-old Fomalhaut belt: a similar CO+CO${}_2$ ice abundance in exocomets and Solar System comets
• Debris Disks in the Scorpius-Centaurus OB Association Resolved by ALMA
• Exocometary gas structure, origin and physical properties around $\beta$ Pictoris through ALMA CO multi-transition observations
• Molecular gas in debris disks around young A-type stars
• The accretion rates and mechanisms of Herbig Ae/Be stars
• A Complete ALMA Map of the Fomalhaut Debris Disk
• ALMA observations of the $\eta$ Corvi debris disc: inward scattering of CO-rich exocomets by a chain of 3-30 M${}_{\oplus }$ planets?
• Five steps in the evolution from protoplanetary to debris disk
• CO mass upper limits in the Fomalhaut ring - the importance of NLTE excitation in debris discs and future prospects with ALMA
• Gas and dust in the Beta Pictoris Moving Group as seen by the Herschel Space Observatory
• A spectroscopic survey of Herbig Ae/Be stars with X-Shooter II: Accretion diagnostic lines
• Planet populations inferred from debris discs: insights from 178 debris systems in the ISPY, LEECH and LIStEN planet-hunting surveys
• A population of transition disks around evolved stars: Fingerprints of planets? Catalog of disks surrounding Galactic post-AGB binaries
• Photoevaporative Dispersal of Protoplanetary Disks around Evolving Intermediate-mass Stars
• The Structure of the Local Interstellar Medium. VI. New MgII, FeII, and MnII Observations Toward Stars Within 100 Parsecs
• On the Ubiquity and Stellar Luminosity Dependence of Exocometary CO Gas: Detection around M Dwarf TWA 7
• The mass and size of Herbig disks as seen by ALMA
• Volatile-Rich Circumstellar Gas in the Unusual 49 Ceti Debris Disk
• Exocomets: A spectroscopic survey
• ALMA 1.3 Millimeter Map of the HD 95086 System
• ALMA Survey of Lupus Class III Stars: Early Planetesimal Belt Formation and Rapid Disk Dispersal
• Photoevaporation of Grain-Depleted Protoplanetary Disks around Intermediate-Mass Stars: Investigating Possibility of Gas-Rich Debris Disks as Protoplanetary Remnants
• Lack of other molecules in CO-rich debris discs: is it primordial or secondary gas?
• Asymmetric mid-plane gas in ALMA images of HD~100546
• Primordial or Secondary? Testing models of debris disk gas with ALMA
• ALMA Observations of the HD~110058 debris disk
• Gas trapping of hot dust around main-sequence stars
• Fomalhaut b could be massive and sculpting the narrow, eccentric debris disc, if in mean-motion resonance with it
• Carbon monoxide gas produced by a giant impact in the inner region of a young system
• Hot exozodiacal dust: an exocometary origin?
• Vertical evolution of exocometary gas: I. How vertical diffusion shortens the CO lifetime
• Effects of disc midplane evolution on CO snowline location
• Rapid CO gas dispersal from NO Lup's class III circumstellar disc
• The COBREX archival survey: improved constraints on the occurrence rate of wide-orbit substellar companions. I. A uniform re-analysis of 400 stars from the GPIES survey
• X-Shooter Survey of Young Intermediate Mass Stars -- I. Stellar Characterization and Disc Evolution
• $\delta$ Scuti pulsations in the bright Pleiades eclipsing binary HD 23642
• An unusually large gaseous transit in a debris disc
• Abundance analysis of stars hosting gas-rich debris disks