Scientists who studied UGC 9684, have longed to find out the star-formation rate for UGC 9684.[5] To do this, they used a Fitting and Assessment of Synthetic Templates code.[7] The scientists used further observations via ultraviolet, both optical and near-infrared and from the luminosity measurements from different databases from GALEX,[8]SDSS and from the final release of the MASS extended source catalog by Jarrett et al. 2000,[9] with all the data retrieved from NASA/IPAC Extragalactic Database.[5]
As for the star formation, they employed a decreasing function of (SFR ∝ e−t ) and also a delayed function (SFR ∝ t × e−t ) as well as the stellar population libraries written from Bruzual & Charlot[10] and Convoy et al.[11] Several metallicity estimates, published by Prieto et al. 2008,[12] Kelly & Kirshner from 2012,[13] whom the majority agreed, it is slightly above solar oxygen abundance 12+ log(O/H) ≈ 9.0 which corresponds to ~2 Z⊙.[5]
Scientists therefore found that the star-formation rate of UGC 9684 is 0.25–0.39 M⊙ yr−1.[5] Apart from that, they found the total stellar mass for the galaxy is M⋆ = (2.0–3.5) × 1010 M⊙ which is a current specific of SFR sSFR ≈ 0.01 Gyr−1. This is higher compared to literature but compatible to large number of recent events in UGC 9684.[5]
Supernovae
Three supernovae and one astronomical transient have been discovered in UGC 9684: SN 2006ed, SN 2012ib, AT 2017cgh, and SN 2020pni. This makes it as one of the most active supernova-producing galaxies.[6]
AT 2017cgh was discovered on March 15, 2017, by Pan-STARRS1[20] Science consortium.[21] It was located 0".0 east and 0".0 north of the nucleus with a magnitude of 17.7.[21] This astronomical transient had an unknown type, and was never officially classified as a supernova.[22]
SN 2020pni
SN 2020pni was discovered on July 16, 2020, by a team of astronomers on behalf of the ALeRCE broker[23] via r-ZTF filters which was taken by a Palomar 1.2m Oachin telescope.[24] It was located 5".7 west and 5".0 south of the nucleus with a magnitude of 17.0.[25] The supernova was Type II[26] in which its progenitor, a massive star,[27] was enriched in helium and nitrogen in relative abundances in mass fractions of 0.30–0.40 and 8.2 × 10−3, respectively.[5]
A first study shows 1 day after the discovery, there is a significant He II emission which has strong flash features.[28] Another study shows during the 4 days after, there was an increase in velocity of hydrogen lines (from ~250 to ~1000 km/s) suggesting complex circumstellar medium (CSM).[5] A presence of dense and confined CSM as well as its inhomogeneous structure, indicates a phrase of enhanced mass loss of the SN 2020pni progenitor a year before the explosion.[5] As of 2023, the supernova has since faded from view.[6]
^Seibert, Mark; Wyder, T.; Neill, J.; Madore, B.; Bianchi, L.; Smith, M.; Shiao, B.; Schiminovich, D.; Rich, R. M.; Conrow, T.; Martin, D. C.; GALEX Catalog Team (2012-01-01). "The Galaxy Evolution Explorer (GALEX) Source Catalogs". American Astronomical Society Meeting Abstracts #219. 219: 340.01. Bibcode:2012AAS...21934001S.